3 Ethnic Groups: Negroid - Caucasoid - Mongoloid

We are aware that the adjectives Negroid, Caucasoid, and Mongoloid have offensive connotations in today’s society. The word Negroid has strong racist connotations that diminish the African people; the word Caucasoid has unsupported connotations of superiority of the Europeans, used by the foolish so called white supremacists; and finally, the term Mongoloid, in addition to alluding to the people of a country, it is also used to refer to humans born with Down syndrome.

Modern anthropology no longer classifies humans into four races, as we studied in school: black, white, yellow and red. The term “race” is no longer used to differentiate human groups but to differentiate the human race from the rest of the living beings that inhabit this planet. Today most anthropologists use the term “ethnic group” instead of “race”, and divide the human race into three major ethnic groups: Negroid, Caucasoid, and Mongoloid. There are also those who classify the inhabitants of Oceania as Australoid, but we think that they belong to a subgroup.

Even at the risk of being misunderstood, we will use these terms in the original sense, without any racist connotation because this article wants to prove precisely that the human race had a common cradle in Africa, and that the physiological differences we exhibit today stem from the long adaptation to the different environments of that unique human ethnic group’s migration.

The Rift Valley, the Cradle of Humanity and Its Saviour
A valley is a land depression surrounded by mountains or hills. There are valleys which are formed by the flowing waters of rivers that carved the land for thousands or millions of years, as is the case of the Grand Canyon in the United States which was carved by the Colorado River.

The first great civilizations in the world were formed along the banks of great rivers: the Egyptian civilization, on the banks of the Nile River; the Mesopotamian civilization, on the land between the Tigris and Euphrates Rivers; the Hindu or Vedic civilization, on the banks of the Ganges River; the Chinese civilization, on the banks of the Yellow River (Huang He); the Mayans, Aztecs, and Incas in Central America.

These rivers provided not only a constant and inexhaustible source of drinking water, but also fish for food, water for agriculture and enriched the land they passed through with their sediments – the most fertile lands on our planet are without question the valleys crossed by these great rivers. Rivers were also channels of communication between peoples and facilitated trade.

There are other valleys that are formed by the slow movement of glaciers that erodes the land into a U-shape, and still others are formed when two adjacent tectonic plates separate, creating a rift between them; the earth above this cleft collapses and sinks. When the Arabian plate separated from the African plate, the Rift Valley was formed, the longest and deepest on the planet. In fact, on each side of the Rift Valley there are no mountains, as seen around the valleys formed by rivers and glaciers, but plateaus.

It begins at the source of the Jordan River in Israel, between Lebanon and Syria, forms the Jordan River valley to the Sea of Galilee, continues into the Jordan Valley to the Dead Sea, then to the Gulf of Aqaba in the Red Sea, proceeds south to enter Africa through Eritrea, Ethiopia, Kenya, Tanzania, and ends in the middle of Mozambique in the Indian Ocean, after travelling more than 3000 kilometers and descending to 500 meters below the sea level.

The Rift Valley is a chain of great lakes such as Lake Victoria which gives rise to the Nile River, Lake Tanganyika, Lake Turkana, Lake Niassa, and many other smaller lakes and rivers. It is known for its year-round temperate climate and fertile land. The biodiversity in the Rift Valley is far superior to the rest of Africa and one of the most bio-diverse in the world.
 
This valley is the birth place of humanity and its development during the Paleolithic period. It is also where the Saviour of the mankind was born and, precisely at the source of the Jordan River in Caesarea Philippi, where the Apostle Peter recognized in Jesus someone more than a prophet – the Messiah, the Son of God (Mark 8:27-30). Whenever a pot is made, a lid is made to go along with it: the pot is humanity, and the lid is Jesus who is the Way, the Truth and the Life for humanity.

From Primate to Human Being
‘Be fruitful and multiply, and fill the earth and subdue it…’ Genesis 1:28
Sixty-six million years ago a 10-kilometer in diameter meteorite crashed into our planet and provoked a winter night that lasted several years, during which 75% of the living beings on Earth died, among them the dinosaurs. The small rodents survived because they lived underground and were able to hibernate for a long time.

Many years passed and the conditions on the planet became favorable again, these rodents evolved into orangutans living in trees, where it was easier to protect themselves and find food, and from these to monkeys, chimpanzees, gorillas and primates. Chimpanzees, bonobos (or pygmy chimps), and humans descended from a primate that lived 6 million years ago. From this primate, a branch evolved into humans and another into chimpanzees; today’s chimpanzees and bonobos are the last species from this latter branch.

For these reasons the Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions, on the part of men experienced in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter - for the Catholic faith obliges us to hold that souls are immediately created by God. Humane Generis of Pius XII, #36

As Humane Generis says, the book of Genesis does not contradict the theory of evolution. It tells the truth of faith, not the truth of science. The fact that human beings have evolved from other living beings and life on the planet comes from a common stock do not constitute a problem to our faith, as long as it is acknowledged that God the Creator of everything and everyone gave the kick start by creating the life that He already knew would flow into a human being. Science cannot really explain in scientific terms how we passed from being a monkey to being a human being.

As the link between us and the monkeys has not yet been found, no one knows how or why humans have evolved while our chimpanzee siblings have not… Was it God who willed this, or genetic mutations, change of climate, food, or all of the above? It may have been a chain of events that occurred like the domino effect: one thing led to another and so on. Some of these factors are the bipedalism that freed the hands, the increase of the cranial capacity that creatively arranges tasks for the hands to perform, tools, the opposable thumb, genetic changes, climate and geological changes that have forced human beings to adapt to the new conditions, etc.

From this highly variable scenario and with many other variables, a monkey emerged smart enough to question its own existence. As an evolutionary chronology of the bipedal human species who have appeared and disappeared in the Rift Valley for 6 million years, anthropology establishes the following species:

•    Ardipithecus ramidus – 4.4 million years
•    Australopithecus afarensis – 3.5 million years
•    Homo habilis – from 2 to 1.4 million years
•    Homo ergaster – from 1.8 to 1.2 million years
•    Homo erectus – from 1.6 million to 150 thousand years
•    Homo neanderthalensis – 150 thousand to 30 thousand years
•    Homo sapiens – from 130 thousand years to date

With the exception of the last one, which is our species, all the others are extinct.

Migration and Miscegenation
The Homo habilis, which is considered to be the first member of the genus Homo, gave rise to Homo ergaster. Some H. ergaster migrated to Asia, where they are called Homo erectus and others to Europe as Homo georgicus, a subspecies of H. erectus. The H. ergaster in Africa and H. erectus in Eurasia evolved separately for almost two million years and presumably separated into two different species.

Homo rhodesiensis, which was descended from H. ergaster, migrated from Africa to Europe and became Homo heidelbergensis and later (about 250,000 years ago) Homo neanderthalensis and Denisova hominins in Asia. The first Homo sapiens, a descendant of H. rhodesiensis, emerged in Africa about 250,000 years ago. Furthermore, around 100,000 years ago, some H. sapiens migrated from Africa to the Levant and joined the Neanderthals living there, with some genetic miscegenation or interbreeding.

Later, some 70,000 years ago, perhaps after the Toba catastrophe, the largest volcanic eruption in 2.6 million years, a small group left the Levant to fill Eurasia, Australia and, later the Americas. A subgroup of them encountered the Denisovans and, after some miscegenation, migrated to fill Melanesia.

In this scenario, most of today’s non-African people are of African origin (“the single-origin hypothesis”, also known as the “Out of Africa” hypothesis). However, there has also been some interbreeding between the Neanderthals and the Denisovans, who evolved locally (“the multiregional evolution hypothesis”). The recent genomic results from Svante Pääbo's group also show that 30,000 years ago at least three main subspecies coexisted: the Denisovans, the Neanderthals, and the Cro-Magnons. Today only the Homo sapiens survived, without the existence of the other species or subspecies.

The Three Wise Men/Magi and the Three Human Groups
On this mountain the Lord of hosts will make for all peoples a feast of rich food, a feast of well-matured wines, of rich food filled with marrow, of well-matured wines strained clear. Isaiah 25:6

The three major ethnic groups are subdivided into several other groups that can also be further subdivided into as many as 5,000 ethnic groups. However, they all descend from Homo sapiens because, as we have seen, all other human species have either merged with the Homo sapiens or disappeared and became extinct. There is therefore no scientific reason for racism, that is, the rivalry between different human groups, since we are entirely and exclusively ALL Homo sapiens who have emigrated from Africa.

• Caucasoid – Aryans, Hamites, Semites
• Mongoloid – Mongolians, Chinese, Indo-Chinese, Japanese and Koreans, Tibetans, Malaysians, Polynesians, Maoris, Micronesians, Eskimos or Inuit, American Indians
• Negroid – Africans, Hottentots, Melanesians/Papua, Negritos, Australian Aborigines

At the Addis Ababa museum in Ethiopia, where 40 % of the skeleton of Lucy (an Australopithecus afarensis dated 3.2 million years ago) is kept, a large sign reads “Welcome Home”. Yes, the Rift Valley is indeed our common home.

From here the #HomoSapiens started their migration that took them to all corners of the earth. As they went from place to place in order to survive, their bodies and  physiology adapted to the environments they came to colonize, branching into the three main ethnic groups that exist today: Negroid, Caucasoid, and Mongoloid. Once again, in as much as God is one and three, so humans are also at the same time one and three; three in one, one in three.

Representing each of the three ethnic groups that humanity had branched into, the three wise men returned to the Rift Valley from where their common ancestor the Homo sapiens originated, to pay homage to the ONE who is the exemplar of Humanity, Jesus Christ, who was also born on the slopes of that valley. Jesus came to bring the fullness of physical, moral, spiritual and psychological health to humanity, and especially to be the great model for all to follow as the way, the truth, and the life. (John 14:6)

Cereals and Civilization
Agriculture and the domestication of animals were already important in the Paleolithic period for the survival of the human species and especially to overcome the symbiosis and dependence man lived in relation to Nature. Before the discovery of agriculture and domestication of animals, human beings, like wild animals, spent most of their day searching for food.

Of all the agricultural products, cereals were the most responsible for establishing a total independence from Nature. A human being is considered an omnivore, but from the point of civilization, he is mainly a cereal eater. Cereals are still today the staple food of man’s diet, they are the base of the well-known food pyramid, from the base to the tip: cereals, vegetables and fruits, meat and fish, and finally, vegetable fats and animal fats.

Why cereals? From the point of view of our diet, cereals, composed of carbohydrates, are energy-rich food that can supply energy for a long time. Vegetables and fruits supply quick but short-lasting energy. Furthermore, of all the foods that we know, cereals take the longest to spoil or degrade: at zero humidity they can last for millennia. In fact, archaeologists have found in the tomb of King Tutankhamen, the Egyptian pharaoh, 5,000-year-old wheat grains that had germinated after sowing.

Where there was no grain there was no civilization because grains, as the story of Joseph in Egypt describes in the book of Genesis 37, and the parable of the rich fool in Luke (12:16-20) indicates, unlike other foods, could be stored and preserved for a long time. This frees human beings from the constant need to search for food thus allowing them to devote themselves to other tasks, forming culture and civilization.

Let us take as an example the Indians of the entire American continent; both the North American Indians, as well as the South American Indians, did not build civilizations because they had no cereal. While the Central American Indians, the Mayans, the Aztecs and the Incas built a highly developed civilization. There were three great civilizations in the ancient world and all of them were based on one or more cereals:

The Wheat Civilization: North Africa and Europe – Egypt flourished thanks to the abundance of grains grown along the banks of the Nile River. Wheat, barley, sorghum, and oats were the first grains with the greatest mastery of cultivation techniques. The pharaohs used wheat as currency. The peasants were paid three loaves of bread and two jugs of beer as payment for a day’s work. In the tombs of the Egyptian pharaohs, pasta, honey, fruits, meat, breads and beer have been found.

The Rice Civilization: Asia and Oceania – Rice is the main staple food of approximately two-thirds of the world’s population, and is the most important crop in many countries, especially in Asia and Oceania. Rice cultivation is as old as civilization. Historians believe that this cereal grain originated in China, India and Oceania. Archaeological discoveries in China and India indicate that rice has existed for 7,000 years. Its use in ceremonies, where the Emperor sowed rice, dates back to 2822 B.C. and represents the most concrete reference of its existence.

The Maize/Corn Civilization: the Americas – Maize was known by pre-Colombian civilization as the food of men and gods. It is the third most important cereal in the world, after wheat and rice, and it has ensured the survival of large populations because of its nutritional value. The men who grew corn needed only to work 50 days a year, which allowed these people to work on the construction of great architectural works.

The Mayans, the Aztecs and the Incas used corn in the form of flour in their diet, in porridge, breads, cakes, tamales. These peoples had a mystical and intense relationship with this cereal. Even in the leaders’ luxurious meals, corn was a must. The preparation of corn included the use of salt and pepper, as well as fermented beverages produced from corn, which are still made today by the Andean peoples. The long-lasting and easy storage for transport of corn contributed to Columbus bringing this staple food from America to Europe.

The African Profile (Negroid)
The physical characteristics of Africans are the following: round skull, very dark skin pigmentation, and black frizzy or curly hair; round black eyes, wide flat nose, large mouth with prominent and thick lips, short and broad chest, sparse body hair and a thin beard.

The main nucleus of this group is located in the African continent. However, there is an eastern branch of this group which is made up of the Australoids, who are the aboriginal people of Australia, India, Melanesia, and parts of Southeast Asia and East Asia, they are also called the Oceanians. The ones from the Solomon Islands in Oceania are so similar to the black Africans that anthropologists cannot distinguish between the two groups. In general, they have dark skin, wavy black hair, short and narrow face with developed body hair, dark brown eyes, large nose, thick lips, elongated head, taller than the average height and some even considered tall.
 
The European Profile (Caucasoid)
The physical characteristics of Europeans are as follows: broad and round skull, light skin pigmentation, and light hair colour with texture ranging from straight to wavy, wide deep-set eyes, thin lips, broad chest, abundant body hair, full beard. They make up 50% of humanity. The main nucleus of Caucasoids is found in the Old World: Europe, Asia and North Africa. It is subdivided into southern or Indo-Mediterranean and northern or Atlantic-Baltic. The southern race has darker skin, hair and eyes, while the northern race presents with lighter skin, hair and eyes.

Those who represent the southern or Indo-Mediterranean race are: Hindus, Tajiks, Armenians, Greeks, Arabs, Italians and Spaniards, which are characterized by wavy black hair, brown eyes, narrow and slightly curved nose with a prominent bridge, narrow face and head in a dolichocephalic and mesocephalic form.

The northern or Atlantic-Baltic race is represented by the Russians, Belarusians, Poles, Norwegians, Germans, English and peoples who live further north; their physical characteristics are: light skin, blond or red hair, gray or blue eyes, long straight nose and tall stature.

The Asian Profile (Mongoloid)
The physical characteristics of Asians are the following: broad skull, medium skin pigmentation between white and yellow, straight black hair, slanted and oblique eyes, prominent cheekbones, straight nose, thin lips, short and broad thorax, sparse body hair.

The Mongoloid ethnic group makes up about 40% of world population and half are Chinese. They live in Asia, in the northern, eastern, central, and southeastern regions, and extend across Oceania and the American continent. Many members of this group are part of the population in the Asian regions that belonged to the former Soviet Union: Yakut, Buryat, Tunguses, Tchuquetches, Tuvinos, Altaios, Ilacos, Aleuts, and Asian Eskimos.

The Mongoloid race is divided into three subgroups:
The Northern or Asian-Continental – also called Central Asian and to which the Buryat and the Mongolians belong. They are known to have lighter skin, hair and eyes, finer hair, thin lips and large flat face.

The Southern or Asian-Pacific – they are represented by the Malays, Javanese, and inhabitants of the Sunda Islands. Their physical characteristics are: tanned skin, narrow and short face, thick lips, wide nose, sometimes wavy hair, shorter stature than the northerners and the Chinese.

The Native American Indians – Their physical characteristics are: straight thick black hair, underdeveloped body hair system, yellowish-white skin, dark brown eyes and broad face.

Physiological Variables
The most notable physiological variables among the three human groups are the skin colour, the type and colour of hair, the shape and size of the nose, the eye shape and colour, and to a lesser extent, the prominence of the cheekbones.

The Skin – From the white of a Scandinavian to the black of a Congolese, the only difference is the latitude at which these two people live. The further north of the equator, the whiter the person becomes, and the closer to the equator, the darker the person becomes. Our bodies need vitamin D which is synthesized by exposing the naked skin to the sunlight. Where the sun is abundant, the skin, acting like a curtain, closes to let in only the amount it needs, and where the is sun is scarce, the skin opens up completely to soak in as much sunlight as is available.

The Nose – In addition to filtering the air of dust and fumes, thus preventing them from reaching the lungs, the nose also regulates the air temperature. Long nose with small nostrils corresponds to cold climates, and small flat nose with wide nostrils corresponds to warm climates.

The Eyes – The greater or lesser concentration of melanin in the skin is responsible for its colour, and this is the same with the colour of the eyes – the darker the colour the more melanin, and the lighter the colour the less melanin. Current studies show that people with blue eyes all descended from the same individual who lived 6,000 years ago in Scandinavia where 89% of people have blue eyes. This percentage goes down as we head south, and changes from blue to green, from green to brown, and then to black, as we move further south. Like the skin and hair colour, the amount of melanin is responsible for this feature.

As for the shape of the eyes, the most distinct difference is between Chinese or Asian eyes and the rest of the world. Studies show that this feature is the result of adaptation to the environment and climate. In the Asian steppes, the constant strong winds, the dust that they raise, the cold, as well as the need to see far, have led the eyes to adapt over the centuries to how they are today.

The Hair – The same melanin that is responsible for the colour of the iris of the eyes and the colour of the skin, is also responsible for the hair colour. The hair texture is related to the temperature of the environment: straight hair is typical of cold climates, curly and frizzy hair like those of the Africans, are typical of hot climates – by turning a thousand and one times, curly hair allows a cushion or air chamber to form between the scalp and the air, thus protecting the head from sunstroke; Africans have what it seems to be an air conditioner on their head.

The Essence of Racism
There is no longer Jew or Greek, there is no longer slave or free, there is no longer male and female; for all of you are one in Christ Jesus. Galatians 3:28

The affirmation and defense of the thesis of the biological inequality of the human races constitute the essence of racism. Racists consider the white race as superior and all other races, like the black and yellow, as inferior. They confuse the concepts of race and nation. What they don’t realize is that race is a biological concept while nation is a sociological concept.

Cultural level does not depend on physiological characteristics, but is determined by economic and social factors. Racist thinking has no scientific basis, instead it shows gross errors in logic and in facts. As the result, it confuses race with nation, people, culture or linguistic group, attributing to social factors, and therefore hereditary, behaviours which have nothing to do with race but are conditioned by culture, the social environment and economic conditions.

Beauty Standards
“Beauty is in the eye of the beholder”, the standard of beauty is conventional; in Africa, there are tribes that like women with long necks; in southern Ethiopia, women cut a slit in their lips to place within this space a small clay disk that they say makes the woman more beautiful; in China and Japan, women with small feet are considered beautiful.

However, Western civilization has inflicted and imposed its beauty standards across the four corners of the globe in such a way that it seems that everyone thinks and perceives what is beautiful like an European or North American. I noticed this during my years in Ethiopia when I tested a group of young people on what they viewed as beautiful. In the mission there was a local nun, young and beautiful, and another Italian nun not as young nor as beautiful; I was astonished to hear the young people when asked which of the two was more beautiful, that they chose the Italian one. I suppose this is the reason why the singer Michael Jackson never accepted his skin colour and sought through several plastic surgeries to make himself white.

It took time for non-Caucasian models to appear on catwalks in fashion shows. Naomi Campbell was the first African supermodel and in some way shocked certain standards and customs of the fashion world. The point is that the beauty standard is not at all scientific, but is purely conventional, arbitrary and circumstantial. If Africa was as successful as Europe and America, the concept of beauty standard would likely be African.

The Irrationality of Racism
There are no Asian, no African, no Caucasian man, because all men came from the African continent from a common stock. Despite having other species of Homo like the Neanderthals who also left Africa, the only Homo species that survived is the Homo sapiens. All others died out or were absorbed into the Homo sapiens pool, so that since 30,000 to 40,000 years ago, there has only been one species of Homo.

The physiological differences of the three main ethnic groups are the result of an adaptation to the environment and are all reversible in the sense that if we moved a tribe from the Congo to Norway, in less than 25,000 years, its members would become blonde with straight hair, blue eyes and white skin. This is why what Martin Luther King said on the day before his murder makes a whole lot of sense, “I dream of the day when men will be judged not by the colour of their skin, but by the content of their character.”

Fr. Jorge Amaro, IMC

3 Periods of the Metal Age: Copper - Bronze - Iron

The Metal Age is the last stage of the Prehistoric Period, significantly shorter than the previous one. It started approximately in 6500 B.C. and continued until 1500 B.C. In search of more suitable materials for his tools, man moved from stone, wood and bone to harder and easier to shape materials. Therefore, he went from copper, the first metal to be discovered, to bronze which is an alloy of copper and tin. Finally, man discovered iron.

Despite iron being the most abundant metal on our planet, it was the last one to be discovered. We can say that since its discovery, we’ve never left the Iron Age because it is still the most used metal in the world today. It conforms to the most sought-after properties in metals – malleability, durability or hardness – so several alloys emerged, like carbon steel, stainless steel, etc. which have more diverse applications, the most important ones being in the automobile industry, shipbuilding and construction industry.

These developments took place in different regions of the world, but mainly in the Middle East, where the Western culture originated, comprising the countries of Mesopotamia, Israel, Assyria and Egypt. With metals, not only did a new activity appeared – metallurgy – but also all human tasks were made easier and became more productive – agriculture, farming, hunting and fishing – thus creating surpluses and giving rise to another new activity: trade. Trade led humans to create means of transporting merchandise and so the wheel, the horse as the driving force and the sail for boats were invented.

Unfortunately, not everything has been positive; metals have also made it possible to manufacture weapons that were used for the first time for purposes other than hunting animals, that is to say, they are now being used against other human beings. It was in the Metal Age that the first kings, the first nations and the first empires were formed out of wars between peoples; thus, another profession appeared, that of warriors. Mesopotamia and Egypt were the first civilizations to appear.

The Copper Age: 6500 B.C. to 2500 B.C.
It is also called the Chalcolithic Age when it is viewed as a transition from the Neolithic and the Bronze Age. Discovered probably by chance, copper rapidly replaced stone, bone and wood in the making of tools. Chalcolithic represents a qualitative leap in relation to the Stone Age, because wood and bones were readily available in nature, while metals are minerals that had to be melted down to be used.

Once copper was discovered, the path to the Bronze Age and from this to the Iron Age represented quantitative leaps. Man realized that the future was in metals and the search for harder and more resistant metals was what gave rise to the transition from copper to bronze and from bronze to iron.

At first, metals were worked with a hammer to be shaped. Later, they realized that it was better to melt it down to achieve more specific and perfect shapes. This is how metallurgy was discovered as a process for making metal objects and tools.

Copper is a very soft and malleable metal. The objects made of copper are not very resistant. It was also at this time that other metals as soft or even softer than copper were discovered: gold and silver. When copper was discovered, man replaced all his tools with this metal, but he quickly realized that, for certain tools, flint stone was more suitable because it was harder and far less malleable than copper. Therefore, rather than for tools or weapons, copper was used for pots and ornaments, and for funeral rituals.

The Bronze Age: 2500 B.C. to 1500 B.C.
In search of a harder metal, man began mixing minerals, until he invented bronze resulting from a mixture of two softer metals: copper and tin. Bronze is an alloy composed of 90% copper and 10% tin. Paradoxically, combining two soft metals produced a hard metal.

Since its discovery, this metal has been widely used throughout the known world; in search of the metal, the first routes leading to the mines were created. Thus, the wheel for land transport, and the boat and sail for sea transport were developed. The expansion of trade brought the Bronze Age to all of Europe and Asia, and to parts of North Africa. Copper came to be more sought after to make bronze than to be used on its own. Since bronze had no match in hardness and strength, all tools were soon made of bronze.

Replacing stone and copper tools and instruments with those of bronze increased the overall production (mainly in agriculture) and the durability of these tools because, as we’ve said, bronze is stronger and more wear-resistant than copper.

The weapons of combat were made of bronze, giving the people who dominated this process more power of conquest, domination and warlike superiority. Bronze was also used in the making of household artifacts (knives, axes, etc.), and hunting weapons, improving the quality of execution of certain services. Finally, it also had an artistic (masks, figurines, etc.) and adornment use (necklaces, bracelets, rings, etc.).

The Iron Age: 1 500 B.C.
It started in the southwestern Asia Minor, in what is today Turkey, and rapidly spread into the Middle East and the rest of Europe. The Hittites were the first people to work with iron and to use it mainly in weapons with which they quickly subjugated other peoples. The warrior using an iron sword broke the bronze sword of his opponent at the first strokes.
 
Iron, more abundant in nature than the previous two metals, required more metallurgical expertise because of its higher melting temperature. For this reason, it was necessary to first improve the production of furnaces in order to subsequently reach higher temperatures to work with iron.

The introduction of iron in the fabrication of the most diverse equipment, tools and weapons brought great changes in the lives of people of that time. Iron came to be used in the production of stronger and more resistant tools, which ended up prompting development in agriculture and facilitating the work of planting.
  
In as far as weapons are concerned, iron helped build swords and other types of stronger weapons. With the introduction of this material, the armies with the strongest weaponry ended up dominating other peoples more easily. Thus, the great empires arose and the emergence of increasingly more powerful kings and rulers.

According to historians, the discovery of writing marks the end of the Iron Age and Prehistory. However, from another point of view, as we mentioned before, we stayed in the Iron Age until the nineteenth century as this metal continued to be the most extensively used material. Just as the combination of copper and tin started the Bronze Age, so the combination of iron with carbon in the last century has ushered in the present Steel Age, as this is the most widely used metal on this planet.

Metal Age Inventions
The furnace – Its invention gave rise to metallurgy in the Metal Age. The improvement of the furnace made it possible to reach higher temperatures to melt iron and create other alloys. It is true that it was also used later in cookware to cook food like bread and meat, and to make ceramic utensils.

The wheel – It allowed the progress of surplus trade, making it possible to transport cargo in less time and with less effort.

The channels – They allowed the water of the rivers to be conveyed to lands far from them, thus obtaining more agricultural surpluses; they were also used to supply water to villages and, with the use of boats, also served as a means of transporting goods.

The boat – The first boats were small boats or rafts; the sail made it possible to build boats of greater draught to carry more people and more goods.

The sail – It served to boost the trade of surpluses created by an increasingly technical and diversified society. The sail was used on boats, but also in windmills; at first it was made of leather, then of more flexible fabric, so as to take better advantage of the driving force of wind.

The plow – Using working animals in combination with the plow made it possible to cultivate more land; it goes without saying that it was first made of copper, then of bronze and finally of iron, as it is still today. With ploughing, the cultivated area quadrupled and the agricultural surpluses caused further development in the previous trade.

The mill – The mill of water, wind and tide increased the production of flour for the making of bread. Before the mill, it was necessary to use the force of man and two stones to grind the grain; after the mill, the driving force of nature was used to generate a continuous movement that allowed large quantities of grain to be ground in a short time.

Weaving – Not yet with maximum strength, but man began to weave or interlace plants to form baskets. Afterwards, linen, cotton and wool were discovered, and threads appeared which, intertwined on the looms, gave rise to the first fabrics, which replaced the skins of animals in clothing.

Stone construction – It was in the Metal Age that walls began to be built around the cities, temples and fortresses. In was at this time that the world’s tallest building was built, at such a height that it was surpassed only 3,000 years later by the Lincoln Cathedral in England. This would be the Great Pyramid of Giza or the Pyramid of Cheops, built around the year 2560 B.C., at 146 meters in height, was surpassed in 1311 by Lincoln Cathedral with the Spire height of 160 meters.

Metal Age Professions
Bosses or kings -- They were distinguished by their leadership skills and physical strength.

Priests – They were in charge of rites and relations with the divinity, they interceded for the people and placated the gods with sacrifices.

Farmers – A profession that was born in the Stone Age that replaced hunting and fishing as a means of obtaining food, and their storage, allowing man a certain independence from land and nature.

Shepherds – It was the activity that replaced hunting; with the domestication of animals, man learned to reproduce them and thus to amass food. For primitive peoples, it was like having money in the bank, for when they sold an animal, they received the interest of a capital invested in the purchase of the animal when it was small.

Blacksmiths or metallurgists – They were the ones who specialized in this new art and craft of the metal era; they became responsible for the making of all the tools that man used.

Potters – They also used furnaces, although at lower temperatures, to bake the clay. It is a very old profession, because apart from baskets, clay was the material most used for all types of vessels, both for storing liquids like water, wine and olive oil, as well as for solids like cereals.

Bonders, weavers, bakers – These were other minor professions that appeared as society structured and organized itself, and diversified its functions and professions.

Merchants – They were born out of relations between the peoples, from agricultural or other surpluses, and from increasing specialization. They were the ones who took products that were plentiful in one place to be traded in another place where they were scarce, making exchanges possible.

The Matriarchy and the Concept of God
“Your wife will be like a fruitful vine within your house; your children will be like olive shoots around your table.” Psalm 128:3

Anthropologists are confident that the first deity to be worshiped was a goddess and not a god. This deity was worshiped as the mother of all that lives; she was identified with the Earth, and with the soil. Therefore, in all languages where there is no neutral gender and everything is defined as either masculine or feminine, uppercase Earth as a planet and lowercase earth as soil are feminine words, and they are also referred to as mother Earth and mother nature, respectively.

Primitive men lived, as animals still do today, in symbiosis with nature, like a baby connected to its mother by the umbilical cord, not in opposition or against her in their thinking. On Earth they lived, and from the earth they drew the sustenance they needed to stay alive.

The same thing seems to happen in relation to themselves: from the woman, like a fruitful land, came the new life that populated the world. It is clear that the connection between the sexual act and the birth of the baby had not yet been established at the time. And why was that? Human intelligence was not yet sufficiently developed to establish the relationship between a cause and an effect, precisely because so much time separated the two (in this case nine months).

I like to take as an example the intelligence of other mammals, for example, mice. If I put a yellow poisonous powder on the ground, some mice will eat this powder and soon after they will die. The other mice immediately establish a sequence of cause and effect and, after a short time, no matter how much yellow powder I put out, no mouse will die because the cause and the effect occurred very close in time, and the mice now know that if they eat of the yellow powder they will die. There was a time when human intelligence was as simple as that of a mouse.

But let us suppose that we put as poison an anticoagulant like warfarin for the mice; the mice eat the poison at will and nothing happens to them, until one day in a fight with other mice or they get injured, they will bleed to death. Nowadays, this poison is the most used to control mice population, because it does not allow them to establish a cause and effect relationship.

The same was true of primitive human beings who did not establish a link between the cause (the sexual act) and the effect (the birth of the infant). For this reason, the woman was seen as the correspondent to Mother Nature, to the mother earth: just as the life of plants on which the animals depended appeared from the womb of the earth, so also the new life was born from the woman’s womb.

It is true that primitive men realized that they were physically stronger than women; but they did not dare to raise their hand against them, just as no man dares even today to raise his hand against his own mother – this is a taboo. We observe this in the mammals closest to us. In the evolution of the species, the breastfeeding females are very aggressive against the males and do not let them approach. Theoretically, these males would win the fight against the females, but they do not react but withdraw out of instinctive respect.

Since the connection between the birth of children and the sexual act had not yet been established, women were the ones who held the power; their fertility gave life to the individual and immortality to the tribe. Because a woman was the origin and source of life, God was conceived as woman, as mother.

Beyond the gift of reproduction and source of life, as still happens today with mammals, man was attracted to the woman who held the power of the sexual act that he craved, for the pleasure it gave him and for the release of the libido.

Self-Consciousness and Patriarchalism
God blessed them, and God said to them, ‘Be fruitful and multiply, and fill the earth and subdue it...’ Genesis 1:28

(...) To the woman he said, ‘I will greatly increase your pangs in childbearing; in pain you shall bring forth children, yet your desire shall be for your husband, and he shall rule over you.’ And to the man he said, ‘Because you have listened to the voice of your wife, and have eaten of the tree about which I commanded you, “You shall not eat of it”, cursed is the ground because of you; in toil you shall eat of it all the days of your life.’ Genesis 3:16-17

When the connection between the sexual act and the birth of a new life was established, the status of man began to rise. The human being has always formed his concept of God based on what he values and considers important, that is, his needs and the concept of himself. For a time, women still enjoyed some of her former status; in fact, god was then represented as matrimony.

The original goddess/mother/earth was complemented by a consort, a father of sky. The rain came down from the sky, it is the divine semen sent by the god-father to impregnate mother earth, so that life can emerge.

Machismo or patriarchalism arose with the outbreak of self-consciousness: when the umbilical cord between man and nature was cut, and he ceased to live in symbiosis with nature, and began to see himself as distinct from her, separate from her. Thus, a difference was established between man and his environment, nature, instinct and self-reflexive thought.

Once the human being was born as a person, survival became less a function of a woman’s reproductive capacity and more a function of a man’s capacity and ability to force nature to meet his needs. The subjugation of the earth corresponded to the subjugation of the woman, for it is the man who now holds the power of reproduction. While the ovum was not identified until 1928, it was thought that the woman was only the receptacle where the man, with his semen, placed the new being in the woman’s womb, the homunculus or very small human, as St. Thomas Aquinas called it.

The story of Abraham can be reinterpreted in this context. Abraham, a man, left his homeland, severing the ties that bound him to Ur of the Chaldean, around 1800 B.C. In an act of self-affirmation and overcoming the need for security, he thus responded to the call of a deity who was also not tied to any place, and he set out into the unknown, as if in search of himself and this deity. From the time of the story of Cain and Abel, it has been known how Yahweh favored the shepherds over the farmers, who are given the more feminine values of fertility.

Throughout human history, only Jesus treated women as equals. We don’t have the space to develop this theme here, but his disciples did not understand or accept this characteristic of the Master and soon returned to the machismo of their cultural environment.

Saint Thomas Aquinas even came to the conclusion that a woman was inferior in nature to a man, and therefore he decreed that the inferior should serve the superior. This attitude has not yet changed, not only in some places on earth, but also in some minds of today’s Western civilization. Therefore, when Pope John Paul I said in public that God was also a mother, he left many Catholics much scandalized. The pope who succeeded him took years to assimilate the same concept, until one day he too declared it in public.

Fr. Jorge Amaro, IMC

3 Periods of the Stone Age: Paleolithic - Mesolithic - Neolithic

The study of the evolution of human race on this planet, which has almost nine million different species of animal and plant life to date, is divided into two great periods: Prehistoric and Historic. The Prehistoric period studies the appearance of the first hominids or ancestors of man and his evolutionary process from 5 million years ago until the invention of writing in 4 000 B.C., when man began to transmit news about himself, reporting his existence. Here the Prehistoric period ends and the Historic Period begins to this day.

This first stage in the evolution of mankind, which is substantially longer than the second, is further subdivided into two stages according to man’s relationship with his environment and with the materials he used. Therefore, we have the Stone Age, during which Man fundamentally used stone to fabricate the tools he needed in his daily life, and the Metal Age, when humans learned, with the help of fire, to fuse some minerals to transform them into metals, and later use them as tools.

The Origin of Life
After so many years of development, advances in science and technology, the origin of life remains a mystery that continues to challenge and baffle scientists. The “big bang” of biology, a definitive and irrefutable theory on the origin of life that is accepted by all, has yet to be discovered. No one has so far managed to recreate the real conditions of primitive Earth when life first appeared; that is to say, no one has been able to turn back the clock and recreate the conditions that favored the transition of inorganic nonliving matter into organic living matter.

The recreation in laboratory of environments that could be similar to that of primitive Earth did not result in the appearance of life form. The old Aristotelian derived theory of spontaneous generation harbored by some, that fully-formed complex living organisms could arise naturally and spontaneously from nonliving matter, has long been put to death once and for all by Louis Pasteur in the nineteenth century with his famous swan-neck flask experiment, from which he concluded that “life only comes from life”.

“The most complex machine man has devised – say, an electronic brain – is child’s play compared with the simplest of living organisms,” wrote American biologist and Nobel Prize winner in Medicine, George Wald. “The especially trying thing is that complexity here involves such small dimensions. It is on the molecular level; it consists of a detailed fitting of molecule to molecule such as no chemist can attempt.”

We know that the force of gravity was responsible for the agglutination of matter and space dust, and the formation of planets and stars. It is unknown if there is an analogous force in biology that causes different organic molecules to come together to form a prokaryotic cell.

To date, all that biology has been able to establish is that, under very peculiar conditions, inorganic molecules can be transformed into organic molecules, but the transition from these simple organic molecules like amino acids to something that is complex enough that it can self-replicate, and endowed with metabolism, remains a great mystery. It is known, however, that the microorganisms at that period used methane or hydrogen for metabolism instead of oxygen: they were organisms with anaerobic metabolism. Fermentation is a modern example of this type of metabolism.

Long before photosynthesis, and the eukaryotic cells that perform it, the first living beings on our planet would have the aspect of single-celled microorganisms or prokaryotic cells, like today’s bacteria and archaea, and would have lived in extreme environments, next to thermal springs in the primitive seas, nourishing themselves from the reactions between inorganic substances. From these first living beings, those capable of carrying out fermentation emerged, later the photosynthetic and, lastly, the heterotrophic beings, that is, living beings that, unlike plants, are not able to produce their own food.

The Evolution of Species
Then God said, “Let the earth put forth vegetation: plants yielding seed, and fruit trees of every kind on earth that bear fruit with the seed in it.” (…) And God said, “Let the waters bring forth swarms of living creatures, and let birds fly above the earth across the dome of the sky.” (…) And God said, “Let the earth bring forth living creatures of every kind: cattle and creeping things and wild animals of the earth of every kind.” And it was so. Genesis 1:11, 20, 24

The theory of evolution of species that Charles Darwin published in 1858 is the result of empirical research conducted during his voyage to the Galapagos Islands, which led him to conclude that life on this planet comes from a common stock, that is, that all living beings on this planet, both plants and animals, are related. All individuals have common ancestors.

The diversification of living beings or the evolution of species occurs by adaptation to the environment and natural selection – the better equipped, the strongest, prevail over the weakest or, as the proverb says, “the weak do not recite history”. Those that best adapt to the environment will eliminate their rivals and manage to pass on their genes to the next generation because the females instinctively allow themselves to be fertilized by the strong and reject the weak.

The first living beings appeared 3.5 billion years ago and one billion years later, the first photosynthetic living beings appeared, followed by the eukaryotes soon after. Around 543 million years ago, there was a period of great explosion of evolutionary changes in life form on this planet known as the Cambrian Period; there are many fossils that document this phase of life on Earth.

The first living beings were the microscopic organisms, primitive plants and invertebrates (worms and arthropods). Fish were the first vertebrates to emerge. It was 570 million years ago that plants invaded the dry land from the sea. Some animals had already done so before, but they did not stay on dry land permanently, because there was no food available there.

Animals came on dry land periodically, but remained most of the time in the sea: these were the amphibians. About 438 million years ago, they began to increase their time on land and 30 million years later, they evolved into reptiles. From the reptiles, evolution took two different paths: some reptiles evolved into mammals and others into birds.

Around 360 million years ago, the dinosaurs reigned on our planet. Some time later, the mammals which already coexisted with the dinosaurs but were insignificant began to stand out. About 245 million years ago, the dinosaurs became extinct and the mammals increased in number due to the absence of predators. About 66 million years ago, the primates appeared. Then 55 million years ago, the common ancestor of the pongids and hominids evolved. The earliest hominids emerged 8 million years ago.

Ontogenesis and Phylogenesis
Ontogenesis recapitulates phylogenesis by postulating that there is a similarity between the aspect of the embryonic stages of the human fetus, from conception to birth, and the development of the different life forms, from the unicellular origin to the human being. It is a discarded theory today, but it is close to the analogy that is often established between different fields of knowledge.

From the conception of an individual to his birth, the evolution of life on Earth is recapitulated, from the single-celled origin to the complexity of a human being. The diverse forms that the embryo acquires in its development resemble, in some way, the forms that life has assumed in the evolution of the species, from the prokaryotic archaea to the human being.
 
Furthermore, after birth, the development of an infant to self-awareness, that is, until he realizes that he exists as a person and begins to communicate, he recapitulates the evolution of the human race from the last primate that was not yet bipedal and did not speak to the Homo sapiens who stand erect walking upright and have the ability to communicate.

The Evolution of Human Life
For these reasons the Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions, on the part of men experienced in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter - for the Catholic faith obliges us to hold that souls are immediately created by God. Humani Generis, 36 – Pope Pius XII, 1950
   
“There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” Charles Darwin, The Origin of Species, 1858

Charles Darwin never said that humans evolved from the present day monkeys. According to the British naturalist, humans, monkeys, chimpanzees and gorillas, all have a series of common ancestors. These ancestors lived on the African continent about 6 and 5 million years ago. Scientists named this species the Sahelanthropus tchadensis.

After this, between 5 and 3.5 million years, the Australopithecus afarensis emerged. Lucy, found in Ethiopia, belongs to this family, which marks the moment when the human race learned to walk. A little later, 2.6 million years ago, the first human tools appeared. Following this, 2.5 million years ago, the Homo habilis appeared, so called for the use he made of the tools.

The mastering of fire took place 1.5 million years ago; food began to be cooked about one million years later, and 400 thousand years ago, Homo neanderthalensis left Africa to inhabit the western part of Eurasia. The Homo sapiens remained in Africa. Then 350 thousand years ago, the Neanderthals developed and occupied Eurasia, from Portugal to Siberia.

About 100 thousand years ago, the Homo sapiens left Africa and appeared in Israel. Five thousand year later, they arrived in Malaysia, and 55 thousand years after that, in Australia. At that same time, they invaded Europe, defeating the Neanderthals or interbreeding with them. About 28 thousand years ago, we have the last evidence of the Neanderthals who became extinct. Fourteen thousand years ago, the Homo sapiens passed from Siberia through the Bering Strait and entered America through Alaska, gradually moving south, until they occupied the entire continent.

The Paleolithic or the Old Stone Age (2.5 million BC – 10 000 BC)
In this era, human beings were nomadic and did not build permanent dwellings. Because of this, they lived in caves, and had to compete with wild animals for this type of habitat. When food in that region was used up, families had to migrate to another region.

They lived by hunting small, medium and large animals, fishing and gathering fruits, leaves and roots. The economy during the Paleolithic phase was subsistence, that is to say, the group did not amass or produce for trade, but only for their own survival.

This period is also known as the age of chipped-stone tools. The first humans, who mastered and knapped stones, had the practice of producing materials by taking two stones and hitting them together to generate sharp points. These artifacts served, especially, for cutting meats and animal skins. They used instruments and tools made from pieces of bones and stones (axes, spears, staves, knives etc.). The goods produced were for collective use and property.

The Discovery of Fire
One of the greatest discoveries of this period was the production of fire through two processes. The most rudimentary was the friction of two stones over a pile of dry straws. The sparks produced ignited the straws.

In a second more elaborate procedure, a small stick was turned in a hole made in a piece of dry wood. This method, through friction, generated heat that passed to the straw, creating the fire.

• As we have commented in another text, fire had a great importance for the cohesion of families and communities, because everyone gathered around the fire for warmth. Since no one wanted to be left out in the cold, fire acted as a deterrent to antisocial attitudes.
• It allowed the light of the day to extend into the night, and because it was impossible to work at night, the two or three hours of tenuous light served for cultural events, to share experiences and for the handing down of culture from parents to children.
• The light in the night promoted safety of human beings in relation to animals that hunted at night, as it served to scare them away.
• However, the most important use of fire at that time was in the preparation of food. Cooked or roasted food has improved human diet. Certain foods are more nutritious cooked than raw. Fire and cooking of food are responsible for population growth and human survival.
• Finally, it was precisely fire that allowed humans to move from the Stone Age to the Metal Age.

The Social Organization
The men organized themselves in small groups, where the leader was the strongest and the most skilled. The men had the task of hunting, fishing and protecting the group. The women had the job of preparing food and caring for the children.

Communication
The communication in this period was based on the emission of some sounds (noises), without the elaboration of words, and physical gestures. Another widely used form of communication was cave paintings (drawings made on cave walls). Through these drawings (cave paintings) men marked time, exchanged experiences and transmitted messages and feelings.

Rituals
In the Paleolithic, men already performed funeral rituals. Archaeologists have found, in various regions, ceramic pots with human remains and personal objects inside caves. Religious rituals were also performed with the use of fire.

Hominids that lived in the Paleolithic Period
Australopithecines, Homo habilis, Homo erectus, Neanderthal Man or Homo neanderthalensis, Homo sapiens and Cro-Magnon Man, the earliest known European.

The Mesolithic or the Middle Stone Age (10 000 BC – 8 000 BC)
The Mesolithic is an intermediate period of the Prehistory, between the Paleolithic and Neolithic periods. This phase did not occur in all the regions of the world, but only in those where glaciation or the ice age had the most considerable effects.

In this intermediate period, the human being became more related to nature and began to make the first experiences of its domination. The nomadic lifestyle and dependence on external food did not allow development. Man learned to domesticate animals rather than hunt them, thus always having food at his disposal. On the other hand, instead of gathering fruits, plants and roots, he began to cultivate them. In this way, he managed to maintain a certain independence from the environment.

According to these regions, many humans maintained a life similar to that of the Paleolithic, depending on whether they were more dedicated to the domestication of animals or the cultivation of crops. The shepherds would be nomadic, for they followed their herds to pasture, while the farmers settled on the most fertile lands near the rivers.

The Neolithic or the New Stone Age (8 000 BC – 4 000 BC)
The Neolithic is also known as the New Stone Age. The beginning of this period is marked by the end of the ice age, a period when almost the entire planet was covered in ice, and ended with development of writing in Sumer in the Mesopotamia region.

The development of agriculture has allowed human beings to have a life less dependent on nature. With this advancement, they no longer needed to gather wild fruits, vegetables and roots, although these activities continued to be practiced.

The domestication of animals (goats, oxen, pigs, horses and birds) also contributed to the improvement in the quality of life. Together with agriculture, the domestication of animals allowed man to significantly increase the amount of food produced, eliminating the dependence on hunting.

As a result of the development in agriculture and the domestication of animals, humans ceased to be nomadic (with no fixed address) to become sedentary (with fixed address). This fact enabled the development of the first communities (tribes, villages, towns and cities). These first communities developed along the banks of rivers and lakes. In addition to meeting basic needs, water took on a new role in human life: the irrigation of crops.

With the increase in food production, the need for storage was created. In the Neolithic period, there was a great development of ceramic art. Vessels and pots were shaped and fired. According to archaeologists, the first ceramic objects were made around 8,500 years ago.

In the first communities that were formed, it became necessary to organize the work. The men were in charge of hunting, fishing and safety of the community (military protection function). The women were left with the tasks of caring for their children, agriculture and food preparation.

With the increase in production came the surplus. In addition to storing for periods of greatest need, men began to exchange these products with other communities. This was the beginning of trade economy.

With more food, there was a significant increase in population. This fact led to the need for more advanced forms of administration, including the establishment of more specific leadership and task allocation within the community.

In the Neolithic, men began to build more resilient dwellings because they needed to remain in fixed locations. Houses of wood, clay and blocks of stone were built in the villages. On the banks of rivers and lakes, stilts were more common (wooden houses with stakes fixed at the bottom of the river or lake).

The first civilizations arose and developed in the Neolithic period. Among them, we can mention: the Mesopotamian civilization (between the Tigris and Euphrates rivers) and the Egyptian civilization (along the banks of River Nile, northeastern Africa).

Conclusion: Unlike animals that have always lived at ease in a symbiotic relationship with Nature, survival and development for humans required an emancipation from it. The use of instruments, made of stone was the first act towards freedom.

Fr. Jorge Amaro, IMC

3 Metabolism Factors - Fuel - Oxidizer - Ignition

After writing about photosynthesis as the process by which plants transform energy into matter, we now address the reverse process: the transformation of matter into energy. Plants burn part of the matter they produce in order to survive and they do so in the same way as other non-vegetative living things. The only difference is that plants only burn what they themselves produce – they are therefore completely independent, while other living beings burn what plants produce because they cannot produce their own food.

In this sense, we are talking about metabolism, which is in fact, a slow controlled combustion reaction where there is an ignition – the moment when the living being is born and begins to inhale oxygen which is the oxidizer for all combustion – and a fuel, the food consumed by each living being. Before we talk about this slow combustion that takes place inside each living thing, let us talk about combustion in general.

The Process of Combustion
Combustion is a chemical reaction between two substances: a fuel and an oxidizing agent, that is, something that facilitates or makes the combustion possible. The oxidizer is always oxygen, and all fuels have something in common: they are of organic origin, that is, they were once living organisms with carbon chains linked to hydrogen or oxygen atoms.

If this is the case then how does our star, the sun, carry out combustion where there is no oxygen and no organic matter? Combustion on Earth is a chemical reaction. Inside the sun and all the stars, combustion is a nuclear reaction; in other words, the pressure inside the sun is so immense that energy is released by nuclear fusion of hydrogen nuclei into helium. 

Back to our reality on Earth, for a combustion reaction to take place, it is not enough to just have a fuel; we need an oxidizer to help in the process or to make it possible. Take a lighted candle, for example – it can burn for hours until all the wax is burned off; but if we put it under a glass dome, it will continue to burn only until all the oxygen is used up. Without the oxidizer and still with a lot of fuel, the flame will nevertheless go out.

In addition to the fuel and the oxidizer, there is still a third component that is essential for combustion: the ignition. The candle does not come lit, someone has lit it; even in the presence of oxygen, the candle would not burn if it isn’t first ignited. Even gasoline, which is far more flammable than a candle, does not burn in the presence of oxygen unless it is ignited. In the case of gasoline, the ignition may even be the heat in the air.

Let us recall that in the second stage of photosynthesis, carbon dioxide is combined with hydrogen to form matter. In combustion, that matter is oxidized, that is, it is combined with oxygen O2 to form carbon dioxide CO2 and water, releasing energy or heat in the process. The energy that is released, shall we say, is the very energy that a plant had previously obtained from the sun and has been amassed in the fossil fuel, be it coal, wood, oil or natural gas.

The Fuel
This is any substance that reacts with oxygen in the air, releasing light and heat. In this way, fire is the process by which matter releases its energy or becomes energy. Whatever the substance, it is always the result of a past photosynthesis. Fuel is amassed or stored up energy, it is matter that can transform into energy, back into something it once was. All it needs is a start, a starter engine, and the presence of an oxidizer which is oxygen.

For much of human history, fuels were from plants, alcohol, vegetable oils such as castor oil, and animal fats. During the first industrial revolution, the first fossil fuel came into use – mineral coal – which for a long time had fed the first man-built engine: the steam engine.

Then came petroleum and its derivatives, diesel, kerosene, and gasoline; also natural gas, first for domestic use, later for industrial use. Finally, nuclear energy emerged, resulted from the fission of uranium atoms, releasing energy that is then harnessed by the principle of the steam engine to move electric generators.

The Oxidizer
We have said that most of the fuels are of organic origin. The same can be said of the oxidizing agent, oxygen. As we have seen in speaking about photosynthesis, oxygen is a component of water; there is no free oxygen in space; what little there is, it is part of the water molecule and exists in space as ice. The same thing happens on Earth: oxygen is in the water and the water is in the sea.

In order to release oxygen from water, we need a source of energy to break water molecules by the process of electrolysis. However, this process does not happen in nature – the natural process from which oxygen is released is by photolysis which occurs in the first stage of this process.

It is plants, both terrestrial and aquatic, that release oxygen into the air when they photosynthesize. If our air is currently composed of 21% oxygen which allows and facilitates all the combustion taking place on our planet, both the active ones without as well as the slow ones within all living beings including plants, we owe it all to the cyanobacteria that have been making oxygen at the bottom of the oceans for millions of years, bubble after bubble, with the help of the sun.

The Ignition
Like we have said earlier, a fuel in the presence of the oxidizer does not burn if it is not ignited. There must be a kick-start. Even our universe needed a starter, and its kick-start was the Big Bang. All combustion reactions need to be started; after that everything progresses automatically. Like the domino tiles placed upright one after the other, the tiles will not fall sequentially without a tipping force on the first tile to initiate the chain reaction.

Ignition can be defined as the minimum temperature at which a fuel begins to burn incessantly. In the early days of mankind, when fire was first discovered, ignition was triggered by the friction between two sticks of wood until a spark occurred. Today all combustion reactions are initiated by an electrical spark or a match. Gasoline engines need a spark to initiate the chain reaction; in diesel engines, the diesel is heated and compressed until it explodes on its own.

The Discovery of Fire
Fire is an active combustion in which and by which substances called fuels are combined with oxygen in the air, producing light, heat and carbon dioxide. The technically correct definition, however, does not fully satisfy our amazement and willingness to understand it. We can’t help but be intrigued with this reality. As if by magical arts, it seems to be present everywhere; when invoked or summoned, it becomes visible and cannot be ignored because it burns, destroys, warms, modifies, melts, and then disappears. Nothing remains as it was, it destroys some realities and creates others, before disappearing again and becoming invisible until summoned or invoked again. Fire and its true nature have always intrigued the human beings. Let us see how the Greek mythology treated this reality.

Prometheus Stole the Fire from the gods
In the Greek mythology, it was the Titan Prometheus, with the condescension of Zeus, who created human beings that should have been obedient to the gods. Always benevolent to his creatures, Prometheus climbed Mount Olympus to steal the fire from the gods in order to provide the humans with the best weapon to master nature.

The human civilization progressed rapidly after that, and this displeased Zeus greatly who punished Prometheus by having him chained to a rock. Every day an eagle sent by Zeus came to eat the Titan’s liver, which re-grew every night only to be eaten again by the eagle on the following day. Despite his agony, Prometheus never repented of his rebellious act and was eventually freed from his torment many years later by the demigod, Hercules who was renowned for his strength.

In this myth, Prometheus is exalted for his intelligence, and more important than strength, for his altruism as the benefactor of humanity, for the risk he took and that despite so much suffering, he did not regret what he did for humanity. The progress of mankind is owed to the fact that man is as creative as God. But even with his creativity, he needed fire in order to truly master nature; with fire, man can blend the existing elements and create new ones. Without fire, he would remain in the darkness of ignorance.

It is impossible not to see in Prometheus certain similarities with Christ of the Christian religion. He represents great resources, notably his remarkable intelligence and prudence, but he also follows the idea of rebellion against established power, the liberation of the oppressed, the sacrifice of self without counting the cost, and finally the creation of a new system to which all have access: the Kingdom of God.

The Fireplace
Fire has not only allowed us to associate and mix elements of different nature, like the fusing of metals and the invention of new stronger alloys, but it has also attracted human beings to gather around it and form communities. The need to stay warm, not to die of cold by being excluded from the fire or from the community, led humans to overcome individualism and to create cohesive communities.

This is the reason why the fireplace evokes in us the fraternal feelings of harmony, peace and love; until very recently, the families of a village were counted by fires: the number of fires of a village was the number of families in the village.

Even today, love is symbolically represented as a fire in countless poems. There is a sonnet by the Portuguese poet Camões that attests to this use of fire as a symbol of love: “Love is a fire that burns yet burns unseen.” In fact, love unites two different people, creates bond, conquer individualism, creates equality between people, and creates alliances, harmony, and fraternal coexistence.

For thousands of years, around the campfire, culture circulated and were handed down by oral tradition: grandparents passed on to their children and grandchildren what they themselves had received from their own parents… Winters were long and longer still were the nights; during the day there was no time for coexistence as it was necessary to fight for life. So beckoning is the fireplace, the reminiscent of our ancestral life, that today there are television channels that broadcast a lit fireplace 24 hours every day!

Fire and Civilization
It was the mastering of fire that helped human beings pass from the Stone Age to the Metal Age. It is true that humans have already seen fire in the volcanoes, or a fire caused by the lightning in a thunderstorm, but they did not know how to invoke it, how to provoke it. The mastering of fire was important to create the first objects of clay and metal. Fire in the preparation of food gave man access to new sources of protein, an improved diet and better absorption of food.

For centuries, the fire remained trapped in the bonfire or in the forge of metals and in the potter’s oven. With the industrial revolution, an engine that functioned like a furnace was invented, which boiled water from which steam would exit to move the pistons that drove the wheels of a locomotive. From here to the propulsion engines, cars, ships, airplanes, rockets, was a short step.

We can read the history of human civilization as the history of fire and its use. Finally, we have the nuclear energy which transforms the heat released by the fission or the splitting of atoms and transmitted to water into mechanical energy to move the electric generator, producer of electricity.

The Genesis of Life
What is the origin of life on Earth? How did inorganic matter become organic matter? How did inanimate atoms and molecules transform into animate matter? Abiogenesis is the science that studies this transition. So far, there have been many theories proposed to explain how inorganic inert matter becomes organic living matter, but none without empirical evidence. That is to say, so far no one has managed to create life in a laboratory from inorganic matter.

The first living being or organism that appeared on our planet was a cell without nucleus, therefore prokaryotic, and without membrane. It appeared 4 billion years ago and is therefore almost as old as our planet which was formed 4.5 billion years ago. These bacteria were the archaea and cyanobacteria that began to carry out photosynthesis and paved the way for other life forms.

Later on, somehow, these cyanobacteria were associated, forming eukaryotic cells with nucleus, reducing the cyanobacteria to the chloroplast of these cells. Cyanobacteria still exist, they predate plants and animals, not being one nor the other; but is at the origin of two life forms: plant and animal.

Contrary to what seems logical, animals, not plants, were the first to leave the sea and populate the land. But if the animals were the first, what did they eat on land since there was nothing at the time? The animals were amphibians and they lived most of their life in the sea, but probably came on land to escape their predators or to lay eggs. However, it is known that the algae colonized the coastal rocks 1.2 billion years ago. Animals were the first to come ashore, but plants were the first to establish above water.

Even though cyanobacteria are also known as “blue-green algae”, they are strictly speaking not algae as the latter are restricted to eukaryotes, they are rather photosynthetic prokaryotes, the only prokaryotes able to produce oxygen.

Combustion and Respiration
Since combustion is the process by which combustible materials are oxidized with a release of energy and carbon dioxide, then, similarly, respiration consists of the oxidation of foods like glucose, amino acids and fatty acids, resulting in the production of energy and carbon dioxide. Until now there is no difference between the two, but in respiration not only is energy formed, other products are also formed, that is, more matter. This is why it is called metabolism, that is, a change or transformation.

Broadly speaking, this would be the only difference. However, if combustion instead of being complete is incomplete, that is, instead of being rapid it is a slow combustion, matter is also obtained, as in the case of respiration or metabolism. Think about how charcoal is made from wood: one places all the wood together in a pyre and cover the pyre with soil, leaving only one hole at the bottom and another at the top of the pyre. The wood burns in slow combustion because we limit the entry of oxygen and after a few days, we have all the wood turned into charcoal. If the oxygen was not limited, we would get ashes instead in no time.

The same is true of a long distance runner: if after the first minutes of running, on feeling tired from the increased heart rate, the athlete begins to breathe through his mouth and does not limit the oxygen intake, he will quickly tire and after spending all the glucose, he’ll have to stop. However, if he limits his intake of oxygen, he will force his body to change the fuel, so that instead of using glucose which burns rapidly and consumes a lot of oxygen, he will start to burn fatty acids which burn without the help of oxygen. In this way, he can run for a long time without altering his breathing or heart rate.

Another physical process of slow combustion is the degradation and rusting of metals, iron in particular. Over time, all objects containing iron, and there are many of them since iron is the most widely used metal, and even steel which is said to be stainless but under certain humid conditions, end up oxidizing, that is, burning or degrading due to the presence of oxygen.

Respiration or the Breakdown of Glucose
Glucose is the most widely used fuel inside living beings; the breakdown of glucose releases the energy that is contained in its chemical bonds. Glucose has 6 carbon, 12 hydrogen and 6 oxygen atoms, and in each bond between atoms there is an energy content. As glucose decomposes, energy is liberated and used by the body. Respiration completely breaks down glucose, turning it into energy and inorganic matter, such as carbon dioxide. There is yet another process that breaks down glucose, but only partially, since it transforms it into other organic products; this process is called fermentation.

Metabolism
According to the definition found in the dictionary, metabolism is the set of transformation that chemical substances undergo inside living organisms. It is these reactions that allow a cell or a system to turn food into energy, which will be used by the cells so they can multiply, grow and carry out their functions.

Metabolism is divided into two stages: catabolism (where there is degradation or breakdown of compounds) and anabolism (where there is the synthesis or formation of compounds). Let us recall that photosynthesis is also a two-stage process, and that the second stage cannot take place without the first. The process of making glucose and the process of its degradation, breakdown or decomposition, are similar.

Photosynthesis, which makes glucose from smaller molecules, is an anabolic constructive pathway; cellular respiration or metabolism, on the other hand, where glucose is broken down into smaller molecules, is a catabolic degradative pathway.

We have seen that in photosynthesis plants make their own food and part of it is used for their own consumption. The making of the food is photosynthesis; its use for self-consumption and growth is metabolism. Therefore, the plant cell is in some way more complex than the animal cell; it has a unique organelle that is lacking in animal cells: the chloroplast, through which it carries out photosynthesis. On the other hand, like the animal cells, it has the mitochondria by which it performs metabolism.

In metabolism, the anabolic phase of the cell uses glucose to construct cellular elements, to replace them when they are damaged or aged, and also for growth. In the catabolic phase, energy is released that maintains the constant temperature of the organism and the general functioning of all the tasks of the same organism.

Metabolism is a controlled combustion and it is not possible without the use of oxygen. In this combustion, the fuel is the proteins, fats and carbohydrates which, combined with oxygen in the air from respiration, produces energy which is used for the general functioning of the body, but is also partly stored for later use, and for the growth of the body. Everything in the universe obeys these same laws, functions in the same or in an analogous way.

In conclusion, if the plant life photosynthesis uses energy to make matter, the animal life metabolism burns that matter to make energy. Animal life metabolism as well as all man-made engines work under the same three principles.

Fr. Jorge Amaro, IMC

3 Reactants of Photosynthesis: Water - Sunlight - Carbon Dioxide

Einstein proved that matter and energy are one and the same, that is, that matter exists in the form of energy and energy in the form of matter. Intangible and invisible energy is susceptible of transforming into tangible and visible matter and vice versa.

If matter and energy did not have this facility to transform from one to the other, there would be no life on our planet. Life on our planet depends on two chemical processes: photosynthesis and combustion (metabolism). The two processes depend on each other, that is, for one to take place the other must also take place. Through photosynthesis, plant cells change sunlight into chemical energy; this chemical energy is then burned by the cell itself in the presence of oxygen.

Photosynthesis is a prebiotic function, that is, it is not yet in itself synonymous to life, because life is always associated with combustion (slow combustion or metabolism). Photosynthesis is the manufacturing of food in the form of glucose (sugar) by the cells; life is the combustion of this food using oxygen as the oxidant. Photosynthesis is carried out by plant cells which have the unique ability to fabricate their own food. This means that plants need not move about to search for food like animals.

However, the chemical reaction that keeps them alive is not photosynthesis, but rather combustion. They consume part of the glucose and oxygen they produce to stay alive, and have the energy to perform more photosynthesis. They release the rest of the oxygen into the air, and the stored glucose is used to feed the animals that eat them. Since photosynthesis can only occur during the day, that is, in the presence of sunlight, during the night the plants consume part of the glucose and oxygen they produce during the day. Even so, they still accumulate energy, that is, they grow and release the oxygen that other living beings need to live.

How did Life Appear on Our Planet
Plants generate all the food that exists on Earth; without them, Earth would be a dead planet. Four and a half billion years ago, Earth was formed from the collisions of thousands of meteorites in the emerging solar system. The planet was initially so hot that its surface was an ocean of lava.

Millions of years after the formation of the planet, Earth entered into a process of gradual cooling and this alteration gave rise to the formation of a thin layer of rock that covered the entire planet. With the cooling down of the Earth’s temperature, a large amount of gases and water vapour were expelled from the Earth’s interior. This process resulted in the gases forming the atmosphere, and the water vapour favoring the appearance of first precipitation.

However, as the temperature was still very high, when the rainwater touched the ground it evaporated instantly. It was only when the ground temperature cooled to below the boiling point of water that water accumulated, and oceans were formed. It was in the oceans that life first appeared.

The Origin of Oxygen
It may seem logical to think that just as water came before life appeared, so should oxygen the oxidizing agent of combustion come before the emergence of life. But this is not what happened. Life or a primitive form of life appeared first, and only then did oxygen appear. We could say that oxygen, although inorganic, has an organic origin. There may have been some oxygen in the Earth’s atmosphere 2.4 million years ago, but it was insufficient to create life. What caused the oxygen level to skyrocket and reach 21% in the atmosphere were the microorganisms called cyanobacteria or blue-green algae.

All oxygen in the atmosphere comes from water molecules. The latter is composed of two hydrogen atoms and one oxygen atom. In order for a water molecule to separate into its two simple elements, an electric current must pass through it. The breaking down process is called electrolysis, and it does not occur naturally. If the same result can be secured naturally, we would not need fossil fuel, and we would have an inexhaustible and eternally renewable source of energy.

Many people think that photosynthesis is the process by which plants turn carbon dioxide (CO2) into oxygen (O2), but this is not so. Oxygen does not come from a chemical reaction of carbon dioxide, but from water. It is produced during the first stage of photosynthesis when electrolysis occurs. The first microorganisms known to carry out photosynthesis on Earth are the cyanobacteria.

Cyanobacteria carry out electrolysis in the first stage of photosynthesis, as they are interested in the hydrogen that water contains, but not in the oxygen which they release. In other words, oxygen is a byproduct of this first stage. Cyanobacteria need the hydrogen because when combined with carbon dioxide, during the second stage of photosynthesis, glucose is synthesized. However, cyanobacteria could not extract hydrogen from water (which contains twice as much hydrogen as oxygen) without releasing oxygen as a “waste” product.

The very first microorganisms to emerge were the thermophiles, that is, they were able to survive in very hot environments, and to convert inorganic substances such as sulfur and carbon into energy. When the temperature of the atmosphere fell to 72 ° C, these microorganisms evolved into cyanobacteria, as this is the maximum temperature at which photosynthesis is feasible.

For billions of years, oxygen has been accumulating in the atmosphere, and the one that rose to the highest layers has become ozone. In this way the environment was formed and the conditions for life to diversify were created. All the plants on our planet feed in the same way as this microorganism, that is, through photosynthesis.

The Morphology of Cyanobacteria
Also known as the blue-green algae, already about 1500 species in 150 genera have been catalogued. Most species live in marine waters, lakes, rivers and even in very humid soils. They exist in a wide range of shapes and sizes: rods, spheres and filaments.

They measure only a few micrometers, that is, they can only be seen with the aid of microscopes. They reproduce asexually, are unicellular, but can be found in colonies or filaments. These microorganisms, in the aquatic ecosystem, form the so-called phytoplankton and are at the base of the food chain of this ecosystem. They carry out oxygenic photosynthesis (they use water as an electron source and release oxygen) and are autotrophic, since photosynthesis is their main way of obtaining energy.

Cyanobacteria appeared on Earth about 3 billion years ago. This dating is confirmed from fossils known as stromatolites, which were formed by these microorganisms. Because they have existed for so long, it is believed that they were responsible for producing the oxygen that accumulated in the primitive atmosphere.

The Chronology of Life on Earth
Our planet Earth was formed 4.5 billion years ago. After water settled in the oceans, the first thermophilic microorganisms appeared about one billion years later. Soon after, the cyanobacteria emerged, when the temperature of the seawater began to allow for photosynthesis. Cyanobacteria are simple microorganisms formed of cells without nucleus, that is, they are prokaryotes.

Two billion years ago, the eukaryotic cells appeared, that is, cells with nucleus that are the fundamental cells for life – all living beings, animals and plants, are made up of eukaryotic cells. Approximately 570 million years ago, there was the explosion of Cambrian life, marked by a burst of diversification of life on Earth, and the first non-plant organisms evolved.

About 438 million years ago, plants which until then only existed in the sea, began to populate the Earth. They were the first to leave the sea, which is logical, since all life on Earth depends on them. Years later, around 408 million years, the first amphibians emerged, the ancestors of the reptiles which came 50 million years later.

The extinction of the dinosaurs, the most emblematic reptiles on our planet, occurred 66 million years ago. After they were dethroned, Earth began to be dominated by mammals, and among them, the primates which came about 55 million years ago. Human beings are believed to have appeared 5 million years ago.

The Components of Photosynthesis
For a plant to able to photosynthesize, that is, to use sunlight to transform solar energy into chemical energy, and therefore be able to manufacture its own food, it needs three inorganic elements: water, sunlight, and carbon dioxide. To these elements we add the particularities of the plant cell, which has one component that animal cells do not have -- chloroplasts.

Water
The water in the vacuoles controls the intumescence or swelling of the plant cell. If the plant is left with little water, it withers; a plant with wilted leaves, that is, they have lost much of their intumescence due to a lack of water, decreases in volume and cannot perform photosynthesis well. Due to the thermal control capacity of water, it is possible for plants to absorb a large dose of solar radiation without temperature rising.

Water not only facilitates photosynthesis by keeping the cell vacuoles operational, but it is also an integral part of this chemical process. Plant chloroplast causes the photolysis of water, that is, it breaks down the water molecule into its simple elements: hydrogen and oxygen. It then releases the oxygen into the atmosphere as a byproduct, combining the remaining hydrogen with the carbon dioxide in the air for the subsequent reaction, which is the production of glucose, the energy and food for plant cells.

Sunlight
Light is a wave of electromagnetic radiation made of photons, with wavelength ranging between infrared and ultraviolet radiation. The light that seems white or transparent reveals part of its complexity when it passes through a prism or tiny droplets of moisture in the atmosphere, forming a rainbow. Of this electromagnetic radiation, only one part is visible to the human eye, and this visible light spectrum ranges from 380 to 760 nanometers, from violet to red.

Sunlight is the only source of energy on our planet. All types of energy that we have on Earth, in the final analysis, come exclusively from the sun. Without oxygen there would be no life, without photosynthesis there would be no oxygen, and without the sun there would be no photosynthesis.

It is the sun that sets into motion the cycles upon which life rests: the oxygen cycle, the water cycle, the nitrogen cycle, and many, many other cycles. Without solar energy this would be a dead and dark planet. It is the solar energy that makes it possible for organic elements to combine and produce organic life.

Carbon Dioxide
This gas is nowadays widely talked about as being responsible for the greenhouse effect, which causes the rising of the atmospheric temperature. It is therefore viewed in a negative light as it does not let heat escape from Earth into the space. But plants need carbon dioxide, and life in general also needs it. All organic molecules are a combination of carbon and hydrogen atoms; a molecule which contains both carbon and hydrogen can never be inorganic.

In photosynthesis, this is precisely what happens: the combination of hydrogen, that the plant obtained from the decomposition of water molecule, with carbon dioxide that it gets from the atmosphere produces glucose, that is, a food for life. In fact, the more CO2 humans emit into the atmosphere, the more plants absorb it and the faster they grow.

The ability of plants to remove CO2 from the atmosphere has doubled, it is as if they want to find the solution to our problem of excessive greenhouse effect. That is why despite tropical deforestation, the planet’s vegetative mantle is increasing. But even so, all the terrestrial and marine forests are not enough to purify the atmosphere and prevent its temperature from rising.

Chlorophyll
Chlorophyll is the light absorbing pigment on the thylakoid membrane inside of the chloroplasts. Plant cells are autotrophic, that is, they make their own food. Animal cells are heterotrophic because they feed on life, that is, on other living organisms and do not make their own food. In some ways, we can say that every kind of life depends on plant life, that is, animal life is a parasite of plant life.

It goes without saying that animal life, especially human life, is much more complex than plant life. However paradoxically, at cellular level, the plant cell has practically everything that the animal cell has, and one more organelle that the animal cell does not have: chloroplasts. Whereas animal cells only carry out metabolism, that is, transform matter (food) into energy, plant cells not only carry out metabolism, but also photosynthesis, the opposite of metabolism, where energy is transformed into matter (food).

It is worth remembering that plant cells also have mitochondria where their metabolism takes place, and like in animal cells, is essentially a slow combustion. The difference is that plant cells metabolize or burn the food they themselves have made, carried out with the help of oxygen, the oxidizing agent which they have also made, and still have leftover of both for other living beings that depend on them to survive.

Chlorophyll carries out the main function of photosynthesis: the extraction of energy contained in sunlight to produce carbohydrates. An interesting aspect is that when we look at the atomic structure of chlorophyll, we see a great similarity with the atomic structure of hemoglobin. The chlorophyll molecule consists of a central magnesium atom, which gives it the green colour, surrounded by a nitrogen-containing ring to which a long carbon-hydrogen side chain is attached. The hemoglobin molecule has the same nitrogen-containing ring but with a central iron atom instead, which gives it the red colour. The chlorophyll molecule has a much longer carbon-hydrogen side chain than the hemoglobin molecule.

There are several types of chlorophyll molecules, each one is tuned to or absorbs different wavelengths of light within the visible light spectrum.

• Chlorophyll a: is the pigment that gives the blue/green colour in plants and absorbs violet and orange light the most, at 430 nm and 660 nm, respectively. It doesn’t absorb green, so the green light is reflected to our eyes
• Chlorophyll b: is the yellow/green pigment present in plants and absorbs mostly blue and yellow light, at 450 nm and 640 nm, respectively. It also does not absorb green.
• Carotenoids: these are yellow, orange, and red plant pigments, present in all photosynthetic organisms; and absorb light maximally between 400 to 550 nm.
• Phycobilins: these are red and blue pigments, found in red algae and cyanobacteria, respectively. They absorb light of wavelengths between 500 and 600 nm. 

The Process of Photosynthesis
It is the most important biochemical process for life on our planet. The second would be metabolism, but without photosynthesis there would be no metabolism, since it is from photosynthesis that the fuel and the oxidizing agent of combustion that we call metabolism are produced. Photosynthesis generates the base of the food chain of the entire planet.

Every day we feed on the sun, whether we are vegans, vegetarians, carnivores, omnivores or pescetarians. Ultimately, what we are essentially eating every day is sunshine!

The Photochemical Stage (Light Dependent)
In the first stage, water plus sunlight releases oxygen by electrolysis or photolysis. The free electrons from the water molecule use the hydrogen released in the photolysis as a carrier to enter the chloroplast organelle, on the thylakoid membrane inside the chloroplast. Here light energy is converted into chemical energy (ATP) and reducing power or electron donor (NADPH). These two substances trigger the next stage or the biochemical stage of photosynthesis. Therefore, ATP and NADPH are the end products of this first stage, in which sunlight is needed.

The Biochemical Stage (Light Independent)
This stage is much more complex than the first, it is also known as the Calvin Cycle. It consists in short of three steps: fixation, reduction, and regeneration. It starts with the most important enzyme in the world, code name RuBisCo. This substance captures carbon dioxide in the atmosphere, mixes it with a molecule called ribulose bisphosphate (RuBP); in short, fixing the carbon from its inorganic form in CO2 into organic molecules (3-PGA). The next step is a reduction reaction in which electrons are gained by the 3-PGA molecules, supplied by NADPH and ATP, to produce G3P molecules. In the last step, some G3P molecules go to make glucose/sugar, and the rest is sent to regenerate RuBP molecules needed for the fixation step and the cycle repeats. The overall chemical formula for the photosynthesis process is as follows:

6CO2 + 6H2O + sunlight = C6H12O6 (sugar) + 6O2

Conclusion
Today the planet is covered with vast forests and wooded areas; yet 70% of the oxygen in the Earth’s atmosphere does not come from land plants, but from the marine plants in the ocean. It was there that photosynthesis began and it’s still there the photosynthesis that provides us with most of the oxygen that we breathe. We could say then that the photosynthesis of land plants feeds our bodies, and that of the sea allows us to breathe.

The complex chemical reaction that uses sunlight to release from water the oxygen that we breathe and combines the remaining hydrogen with the carbon dioxide in the air to produce the food we eat, is indeed the Big Bang of life on Earth.

Fr. Jorge Amaro, IMC