From Mud Pies to Mars Rockets: The Rollicking Tale of How We Became Human

Long before the discovery of science and the knowledge of evolution reached us, ancient humans nursed all manner of mythical, imaginative, and spiritual beliefs about their own origins and the origins of humankind at large. Back then, with no Google search and no Darwin's book to consult, they let their imaginations run so wild that even today's film directors might bow their heads in reverence at the sheer inventiveness! In some civilizations, it was believed that some divine power or god, having nothing better to do in his idle hours, shaped man exactly as a potter shapes toys out of clay. But looking at the antics of modern humanity, one begins to suspect that the potter perhaps abandoned the model halfway through and fled the scene! Elsewhere, much like in Greek mythology, it was said that the first human was moulded from clay mixed with water — which, if you think about it, suggests that our earliest ancestors were born not in some genetics laboratory but from the muddy puddles of a monsoon downpour, and that is perhaps precisely why the human mind remains forever muddled to this day! Some tribal communities went a step further, believing their true grandfathers to have been a lion, a tiger, a bear, or even a tree. Others claimed that all around was nothing but a boundless expanse of water, and that from this primordial ocean, humanity and all living creatures suddenly rose up. And yet others insisted that the entire universe and the human race had burst forth from a colossal cosmic egg, or Hiranyagarbha, the golden womb.

Ancient humans believed themselves superior to all other creatures because they alone could speak, think, write, and accomplish the impossible through the strength of their intellect — feats no other creature could match. Possessed of these qualities, ancient humans considered themselves not mere animals but the children of God.

Before the discovery of science and the knowledge of evolution reached us, then, ancient humans held fast to precisely such a colourful assortment of mythical, imaginative, and spiritual beliefs about their own creation and that of the human race entire. Then, a mere two centuries ago, along came a stubborn scientist with spectacles perched on his nose — one Charles Darwin — who snatched the storybooks of fantasy from everyone's hands and declared: "Now listen here, friends — you were not born from any divine egg or lump of clay. You are simply the modern descendants of an ancient line of Primates!"

The moment this was heard, everyone's blood boiled — from the household shrines of ordinary folk to the learned scholars perched at the very summit of civilization. Religious leaders fumed and thundered: "We are God's own special creation, and here these scientists are turning us into mere monkeys leaping about in the trees!" People at first flatly refused to accept this and dismissed Darwin as a madman.

But can truth ever remain hidden out of fear? Scientists kept digging up the earth, unearthing fossil after fossil, and laid the proof right under everyone's nose. In the end, society was forced to concede: "Very well, friend — if Primates truly were our ancestors, then so be it!" Gradually, society came to accept the theory of evolution and learned, at last, what our history had truly been.

The Age of Reptiles Comes to an Abrupt End

About sixty-six million years ago, a bloodthirsty meteor came baring its teeth toward Earth from the depths of space. The dinosaurs, alas, were illiterate — they had built no satellites and so had not the faintest idea what was coming. The moment the asteroid struck the Chicxulub region of present-day Mexico, the entire dynasty of dinosaurs was wiped out for good. What remained were a handful of fossils, which today's researchers use to show off their scholarly credentials. Yet it was precisely because of the dinosaurs' extinction that the story of an entirely new class of creatures began. Their far, far, far, far more recent descendants would eventually come to be known as primates. These primates evolved roughly sixty-five to fifty-five million years ago, during the Cretaceous-Paleogene period, most likely descending from small mammals known as plesiadapiforms.

Plesiadapiforms were nothing like the massive dinosaurs — they were tiny, squirrel-like creatures, and for fear of becoming easy prey to predators by day, they took to leaping about the treetops at night, snatching insects to eat. Something of the plesiadapiform's traits and form still survives, to some degree, in modern treeshrews and colugos. Yes — these plesiadapiforms were the most ancient ancestors of today's ravenous Homo sapiens.

The Great Primate Diaspora

Once the first primates had evolved, they spread across various geographical regions. Whether or not they knew much else, apes and humans alike — all primates — have always been rather accomplished at scattering far and wide and producing litter after litter of offspring. The earliest primates were no exception.

In those days, the arrangement of the continents was quite different from today, with North America, Europe, and Asia joined together, which made it far easier for early primates to migrate from one continent to another. And leap they did — who was going to stop our primate ancestors from bounding about? They fanned out across the earth, and wherever they landed, they promptly settled down and multiplied their numbers with litter after litter of young.

During the Eocene epoch, some fifty-five to thirty-four million years ago, primates spread across North America and Europe. Fossils of early primates belonging to groups such as Adapiformes and Omomyiformes have been found in this region. But some primates grew rather more adventurous still, and even where oceans separated continents like Africa and South America, primates managed to cross via a process known as rafting. Today, their distant descendants, Homo sapiens, proudly point to certain evidence suggesting that these early primates may have drifted across the seas on floating trees or clumps of vegetation to reach other continents.

Platyrrhini — the so-called "New World monkeys" — arrived in South America from Africa via this very rafting process, roughly forty to thirty-five million years ago. Primates proved capable of adapting to a variety of environments, be it forest, savannah, or mountain, and their dietary habits — feeding on fruit, leaves, and insects — along with their arboreal lifestyle and social structures, helped them establish themselves across diverse regions. Being omnivorous, in fact, proved a great boon for our primate ancestors. Reading this ought to make the blood of every self-declared vegetarian — genuine, fake, or part-time — boil with indignation, for their own most ancient ancestors were shameless opportunists who devoured whatever came their way: fruits, roots, eggs, even small creatures.

The movement of tectonic plates, too, played its part in the primates' spread. As the continents drifted apart, primates evolved separately in their respective regions, giving rise to distinct primate species. While Catarrhini — the "Old World monkeys" — remained in Africa and Asia, Platyrrhini evolved in South America.

The scientists of the eighteenth century, it seems, had rather less pressing work on their hands, for they named Catarrhini and Platyrrhini simply by looking at their noses! Those whose nostrils were a touch broader and opened out to the sides were dubbed Platyrrhini — meaning "flat-nosed." And those whose nostrils were narrower and pointed downward were dubbed Catarrhini — meaning "down-nosed." There was one more distinction between these two branches of the family. The Platyrrhini cousins found their tails enormously useful — for many of them, the tail functioned almost like a fifth limb, letting them swing from branches, snatch up their young, and generally live a life of ease. The Catarrhini cousins, on the other hand, seem to have reasoned, "What's the use of lugging around such a long tail?" And so, in the branch of their lineage that eventually evolved into the Great Apes, the tail — having become entirely superfluous — vanished altogether!

Among the very last branches of that long evolutionary history of the Catarrhini lineage stands Homo sapiens. Which is to say: the very creature that proclaims itself the most intelligent being on Earth is, in truth, nothing more than a "tailless Catarrhine"!

The Rise of the Apes

About thirty-five to thirty million years ago, during the Oligocene epoch, fortune smiled upon the Catarrhine primates evolving in Africa. Drawn to the warm forests, abundant fruit, and favourable conditions there, they made it their permanent address. Over millions of years, through gradual transformation, they became the genus Aegyptopithecus. As difficult as the name Aegyptopithecus is to pronounce, its achievements were correspondingly grand. Nature enlarged their brains somewhat, sharpened their eyesight, and effectively awarded them a doctorate in the art of leaping from branch to branch.

Then, roughly twenty-five to twenty-three million years ago, came the Miocene epoch.

The Catarrhine lineage split into two great branches — on one side, the Old World Monkeys, and on the other, the Hominoidea, the great superfamily of apes. The first celebrated member of this new Hominoidea family was Proconsul. For this fellow, history had, in effect, already been made before he even lost his tail. He learned to walk along branches without the aid of a tail, ate his fruit, and perhaps occasionally mused, "Wouldn't it have been rather more convenient to have kept that tail after all?"

From Proconsul emerged Afropithecus. As their line grew, another species appeared — Kenyapithecus. Around twenty to fifteen million years ago, when land connections re-formed between the continents, Kenyapithecus and many other ape lineages set out from the forests of Africa on a migration toward Europe and Asia. Their passports, it seems, carried an "Unlimited World Tour" visa, for wherever their fancy took them, they went leaping and swinging along without a moment's hesitation! In Europe, tailless apes such as Dryopithecus, Ouranopithecus, and Griphopithecus made quite a name for themselves, while in Asia, it was Sivapithecus. Looking at the skull of Sivapithecus, scientists still chuckle today and say, "Well now! This one looks as though it's stepped straight out of the old family album of the orangutan lineage!"

Many of the apes that journeyed to Europe and Asia, however, eventually died out due to climate change. Meanwhile, the branch of Hominoidea that remained in Africa survived and thrived. There, their evolution continued for millions upon millions of years. About ten million years ago, the lineage of gorillas branched off from the rest. Finally, around seven to six million years ago, came that historic moment. One African lineage seemed to say, "Let's become chimpanzees." And the other lineage said, "No — let's take a slightly different path." That second lineage is Hominini, and it was they who became the ancestors of humankind.

Coming Down from the Trees

At just this time, Africa's climate began turning drier. In place of dense forest, the savannah grasslands gradually spread. Opportunities to leap from tree to tree grew scarcer, leaving little choice but to climb down and take to the ground. Nature seemed to be saying: "Well, my dears, you've had your fun playing in the trees all this while. Now come down and take a good look — see how the world looks from here!"

Into this transformed world stepped Sahelanthropus tchadensis, roughly seven to six million years ago. Neither fully human nor fully ape, this creature made the first tentative, courageous attempts to stand and walk on two legs.

Thereafter began another thrilling chapter in the lives of our hominin ancestors. Around six to four million years ago, figures such as Orrorin and Ardipithecus wandered the forests of Africa. They had not yet fully severed their ancient ties to the trees — still climbing branches, yet also coming down to practice tentative bipedal walking. Ardipithecus ramidus, in particular, was a rather clever and playful character. It loved climbing trees, yet also made efforts to walk upright on the ground. Unable to fully abandon the trees, nor fully embrace the ground, it lived out its life in a state of perfect indecision!

About four million years ago, the Australopithecus lineage took to the stage. It was through the skeleton of "Lucy" that humanity first came to know this branch of the family. Poor Lucy, while alive, had no idea that millions of years later, Homo sapiens would write fat volumes and publish research papers about her very bones! Lucy was rather accomplished at walking upright on two legs, yet whenever the chance arose, she never forgot to climb a tree — old habits, it seems, die hard! This lineage later split into two separate branches. On one side, the Paranthropus lineage evolved, developing massive teeth and powerful jaws suited to chewing tough leaves and roots. On the other side, our own genus Homo seems to have reasoned, "No — rather than investing in brawn, it might serve us better to invest a little more in brains."

About 2.4 million years ago came the emergence of Homo habilis — whom scientists call "Handy Man," or the skilled craftsman among humans.

Their brain size grew considerably larger than before. Rather than seeing a stone lying on the ground as a mere pebble, they thought, "Sharpen this stone a little, and it'll make a fine cutting tool!" And thus began the first technology of human civilization — the stone tool! About two million years ago came Homo erectus, an utterly bold and adventurous wanderer. They ventured beyond the borders of Africa — into Asia, into Europe. Long legs, an upright frame, a sturdy build, and more advanced stone axes carried them to far-flung corners of the world. Later, Homo erectus also mastered the art of taming fire. Nature, one imagines, must have been thinking to herself: "This new model bears careful watching — they've gone and learned to play with fire!"

Time rolled on. About eight hundred thousand years ago, humans such as Homo heidelbergensis grew still more resourceful — hunting large game, working together in groups, and sharpening their weapons further still.

Enter Us

At last, about three hundred thousand years ago, our own species, Homo sapiens, emerged in Africa. After millions upon millions of years of trial and error, Nature had produced her latest and most refined "premium edition" yet!

Nature equipped them with every advanced faculty and sent them out into the world — a vast brain, complex language, the ability to plan for the future, art, music, and boundless curiosity, among countless other gifts, were all bestowed upon Homo sapiens. Yet one old family ailment had not been cured — wanderlust! Just like our primitive primate ancestors, Homo sapiens too could never sit still and content in one place. About seventy to sixty thousand years ago, they left Africa and set out toward the Middle East. There, they encountered the mysterious Neanderthals. In some places there was rivalry, in others peaceful coexistence as neighbours, and in yet others, romance and marriage took place! That is precisely why, to this day, a small portion of Neanderthal ancestry survives in the DNA of most people across Europe and Asia.

Some groups of Homo sapiens then travelled along the coastline and reached South Asia. India, at the time, offered plentiful food, though the land was also thick with fearsome predators. But armed with advanced hand tools and knowledge of fire, Homo sapiens made India their home. They did not merely settle — they multiplied. Food was never scarce. Feasting on fish, crabs, shellfish, fruits, and roots — whatever they could find — they bred litter after litter of offspring, until the population grew so large that they were forced, once again, to set out in search of new lands. Many groups moved on to Southeast Asia, and from there, roughly sixty-five to fifty thousand years ago, they sailed by boat all the way to Australia. By that point, our Homo sapiens ancestors had thoroughly mastered the art of seafaring. Some groups travelled from India through Southeast Asia into China and Japan. Another group went from India to Tibet and eastern Russia. Yet another set out from India through Iran into Europe and Central Asia. India, at this time, became the central hub of Homo sapiens' expansion — which is precisely why India is sometimes called the "Beehive of Humankind."

Meanwhile, other groups of Homo sapiens set out from Africa northward, reaching the frigid regions of Europe and Central Asia. There, they had to contend with brutal cold, snow, and enormous beasts such as mammoths. They sewed and wore garments of animal hide, crafted sharp spears, and painted astonishingly beautiful images on cave walls. It seemed as though humanity's very first "art gallery" had just opened its doors!

In the icy reaches of Asia, they crossed paths with yet another mysterious group of humans — the Denisovans. Here too, a certain "family relationship" blossomed. To this day, traces of Denisovan ancestry survive in the DNA of Tibetans, Melanesians, people of eastern and northeastern India, and certain other Asian populations.

During the last Ice Age, with much of the ocean's water locked away as ice, sea levels dropped considerably. As a result, a land bridge known as the Bering Land Bridge emerged between Siberia and Alaska. Humanity, it seems, declared: "Ah! The earth has opened up a new road for us — let's go explore a little further!" About twenty to sixteen thousand years ago, Homo sapiens reached the American continent and, before long, had spread from North America all the way down to South America.

Throughout this long journey spanning millions upon millions of years, the greatest weapon of Homo sapiens was never merely the stone spear or the flint knife. Their true strength lay in working together in coordinated groups, exchanging knowledge through language, adapting swiftly to unfamiliar environments, and constantly inventing new things. It was this extraordinary combination of traits that allowed Homo sapiens to extend their dominion into every corner of the earth.

And so, in the end, that same lineage of primates — who once swung from tree branches for millions upon millions of years, who lost their tails, who learned, hesitantly, to walk upright on two legs, who hammered and ground stones into tools — now dresses itself in suits, lands on the moon, builds rockets bound for Mars, constructs artificial intelligence, and sits before computer screens writing delightful essays about its own most ancient ancestors!

Nature, one imagines, must be watching all this with a quiet, private smile, thinking to herself: "That tiny, squirrel-like creature, once leaping about the treetops hunting for insects to eat — never in my wildest dreams did I imagine its descendants would one day travel so far!"

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Here is a reference list of books covering the topics discussed in this essay — primate evolution, hominin evolution, and the emergence of Homo sapiens:

1.Dawkins, Richard. The Ancestor's Tale: A Pilgrimage to the Dawn of Life. Boston: Houghton Mifflin, 2004.

2.Harari, Yuval Noah. Sapiens: A Brief History of Humankind. New York: Harper, 2015.

3.Stringer, Chris. Lone Survivors: How We Came to Be the Only Humans on Earth. New York: Times Books, 2012.

4.Tattersall, Ian. Masters of the Planet: The Search for Our Human Origins. New York: Palgrave Macmillan, 2012.

5.Wong, Kate, and Ian Tattersall. Extinct Humans. Boulder: Westview Press, 2000.

6.Fleagle, John G. Primate Adaptation and Evolution. 3rd ed. San Diego: Academic Press, 2013.

7.Johanson, Donald, and Maitland Edey. Lucy: The Beginnings of Humankind. New York: Simon & Schuster, 1981.

8.Klein, Richard G. The Human Career: Human Biological and Cultural Origins. 3rd ed. Chicago: University of Chicago Press, 2009.

9.Reich, David. Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past. New York: Pantheon Books, 2018.

10.Boyd, Robert, and Joan B. Silk. How Humans Evolved. 8th ed. New York: W. W. Norton, 2020.