As with the new squirrel, we can start by comparing him with other species that appear to be most closely related. From his teeth, his hands, his eyes and various other anatomical features, he is obviously a primate of some sort, but of a very odd kind. just how odd becomes clear when we lay out in a long row the skins of the one hundred and ninety-two living species of monkeys and apes, and then try to insert a human pelt at a suitable point somewhere in this long series. Wherever we put it, it looks out of place. Eventually we are driven to position it right at one end of the row of skins, next to the hides of the tailless great apes such as the chimpanzee and the gorilla. Even here it is obtrusively different. The legs are too long, the arms are too short and the feet are rather strange. Clearly this species of primate has developed a special kind of locomotion which has modified its basic form. But there is another characteristic that cries out for attention: the skin is virtually naked. Except for conspicuous tufts of hair on the head, in the armpits and around the genitals, the skin surface is completely exposed. When compared with the other primate species, the contrast is dramatic. True, some species of monkeys and apes have small naked patches of skin on their rumps, their faces, or their chests, but nowhere amongst the other one hundred and ninety-two species is there anything even approaching the human condition. At this point and without further investigation, it is justifiable to name this new species the ‘naked ape’. It is a simple, descriptive name based on a simple observation, and it makes no special assumptions. Perhaps it will help us to keep a sense of proportion and maintain our objectivity.
Staring at this strange specimen and puzzling over the significance of its unique features, the zoologist now has to start making comparisons. Where else is nudity at a premium? The other primates are no help, so it means looking farther afield. A rapid survey of the whole range of the living mammals soon proves that they are remarkably attached to their protective, furry covering, and that very few of the 4’x3‘7 species in existence have seen fit to abandon it. Unlike their reptilian ancestors, mammals have acquired the great physiological advantage of being able to maintain a constant, high body temperature. This keeps the delicate machinery of the body processes tuned in for top performance. It is not a property to be endangered or discarded lightly. The temperature-controlling devices are of vital importance and the possession of a thick, hairy, insulating coat obviously plays a major role in preventing heat loss. In intense sunlight it will also prevent over-heating and damage to the skin from direct exposure to the sun’s rays. If the hair has to go, then clearly there must be a very powerful reason for abolishing it. With few exceptions this drastic step has been taken only when mammals have launched themselves into an entirely new medium. The flying mammals, the bats, have been forced to denude their wings, but they have retained their furriness elsewhere and can hardly be counted as naked species. The burrowing mammals have in a few cases—the naked mole rat, the aardvark and the armadillo, for example—reduced their hairy covering. The aquatic mammals such as the whales, dolphins, porpoises, dugongs, manatees and hippopotamuses have also gone naked as part of a general streamlining. But for all the more typical surface-dwelling mammals, whether scampering about on the ground or clambering around in the vegetation, a densely hairy hide is the basic rule. Apart from those abnormally heavy giants, the rhinos and the elephants (which have heating and cooling problems peculiar to themselves), the naked ape stands alone, marked off by his nudity from all the thousands of hairy, shaggy or furry land-dwelling mammalian species.
At this point the zoologist is forced to the conclusion that either he is dealing with a burrowing or an aquatic mammal, or there is something very odd, indeed unique, about the evolutionary history of the naked ape. Before setting out on a field trip to observe the animal in its present-day form, the first thing to do, then, is to dig back into its past and examine as closely as possible its immediate ancestors. Perhaps by examining the fossils and other remains and by taking a look at the closest living relatives, we shall be able to gain some sort of picture of what happened as this new type of primate emerged and diverged from the family stock.
It would take too long to present here all the tiny fragments of evidence that have been painstakingly collected over the past century. Instead, we will assume that this task has been done and simply summarise the conclusions that can be drawn from it, combining the information available from the work of the fossil-hungry palaeontologists with the facts gathered by the patient ape-watching ethologists.
The primate group, to which our naked ape belongs, arose originally from primitive insectivore stock. These early mammals were small, insignificant creatures, scuttling nervously around in the safety of the forests, while the reptile overlords were dominating the animal scene. Between eighty and fifty million years ago, following the collapse of the great age of reptiles, these little insect-eaters began to venture out into new territories. There they spread and grew into many strange shapes. Some became plant-eaters and burrowed under the ground for safety, or grew long, stilt-like legs with which to flee from their enemies. Others became long-clawed, sharp-toothed killers. Although the major reptiles had abdicated and left the scene, the open country was once again a battlefield.
Meanwhile, in the undergrowth, small feet were still clinging to the security of the forest vegetation. Progress was being made here, too. The early insect-eaters began to broaden their diet and conquer the digestive problems of devouring fruits, nuts, berries, buds and eaves. As they evolved into the lowliest forms of primates, their vision improved, the eyes coming forward to the front of the face and the hands developing as food-graspers. With three-dimensional vision, manipulating limbs and slowly enlarging brains, they came more and more to dominate their arboreal world.
Somewhere between twenty-five and thirty-five million years ago, these pre-monkeys had already started to evolve into monkeys proper. They were beginning to develop long, balancing tails and were increasing considerably in body size. Some were on their way to becoming leaf-eating specialists, but most were keeping to a broad, mixed diet. As time passed, some of these monkey-like creatures became bigger and heavier. Instead of scampering and leaping they switched to brachiating—swinging hand over hand along the underside of the branches. Their tails became obsolete. Their size, although making them more cumbersome in the trees, made them less wary of ground-level sorties.
Even so, at this stage—the ape phase—there was much to be said for keeping to the lush comfort and easy pickings of their forest of Eden. Only if the environment gave them a rude shove into the great open spaces would they be likely to move. Unlike the early mammalian explorers, they had become specialised in forest existence. Millions of years of development had gone into perfecting this forest aristocracy, and if they left now they would have to compete with the (by this time) highly advanced ground-living herbivores and killers. And so there they stayed, munching their fruit and quietly minding their own business.
It should be stressed that this ape trend was for some reason taking place only in the Old World. Monkeys had evolved separately as advanced tree-dwellers in both the Old and the New World, but the American branch of the primates never made the ape grade. In the Old World, on the other hand, ancestral apes were spreading over a wide forest area from western Africa, at one extreme, to south-eastern Asia at the other. Today the remnants of this development can be seen in the African chimpanzees and gorillas and the Asian gibbons and orangutans. Between these two extremities the world is now devoid of hairy apes. The lush forests have gone.
What happened to the early apes? We know that the climate began to work against them and that, by a point somewhere around fifteen million years ago, their forest strongholds had become seriously reduced in size. The ancestral apes were forced to do one of two things: either they had to cling on to what was left of their old forest homes, or, in an almost biblical sense, they had to face expulsion from the Garden. The ancestors of the chimpanzees, gorillas, gibbons and orangutans stayed put, and their numbers have been slowly dwindling ever since. The ancestors of the only other surviving ape—the naked ape—struck out, left the forests, and threw themselves into competition with the already efficiently adapted ground-dwellers. It was a risky business, but in terms of evolutionary success it paid dividends.
The naked ape’s success story from this point on is well known, but a brief summary will help, because it is vital to keep in mind the events which followed if we are to gain an objective understanding of the present-day behaviour of the species.
Faced with a new environment, our ancestors encountered a bleak prospect. They had to become either better killers than the old-time carnivores, or better grazers than the old-time herbivores. We know today that, in a sense, success has been won on both scores; but agriculture is only a few thousand years old, and we are dealing in millions of years. Specialised exploitation of the plant life of the open country was beyond the capacity of our early ancestors and had to await the development of advanced techniques of modern times. The digestive system necessary for a direct conquest of the grassland food supply was lacking. The fruit and nut diet of the forest could be adapted to a root and bulb diet at ground level, but the limitations were severe. Instead of lazily reaching out to the end of the branch for a luscious ripe fruit, the vegetable-seeking ground ape would be forced to scratch and scrapa painstakingly in the hard earth for his precious food.
His old forest diet, however, was not all fruit and nut. Animal proteins were undoubtedly of great importance to him. He came originally, after all, from basic insectivore stock, and his ancient arboreal home had always been rich in insect life. Juicy bugs, eggs, young helpless nestlings, tree-frogs and small reptiles were all grist to his mill. What is more, they posed no great problems for his rather generalise digestive system. Down on the ground this source of food supply was by no means absent and there was nothing to stop him increasing this part of his diet. At first, he was no match for the professional killer of the carnivore world. Even a small mongoose, not to mention a big cat, could beat him to the kill. But young animals of all kinds, helpless ones or sick ones, were there for the taking, and the first step on the road to major meat-eating was an easy one. The really big prizes, however, were poised on long, stilt-like legs, ready to flee at a moment’s notice at quite impossible speeds. The protein-laden ungulates were beyond his grasp.
This brings us to the last million or so years of the naked ape’s ancestral history, and to a series of shattering and increasingly dramatic developments. Several things happened together, and it is important to realise this. All too often, when the story is told, the separate parts of it are spread out as if one major advance led to another, but this is misleading. The ancestral ground-apes already had large and high-quality brains. They had good eyes and efficient grasping hands. They inevitably, as primates, had some degree of social organisation. With strong pressure on them to increase their prey-killing prowess, vital changes began to take place. They became more upright—fast, better runners. Their hands became freed from locomotion duties—strong, efficient weapon-holders. Their brains became more complex—brighter, quicker decision-makers. These things did not follow one another in a major, set sequence; they blossomed together, minute advances being made first in one quality and then in another, each urging the other on. A hunting ape, a killer ape, was in the making.
It could be argued that evolution might have favoured the less drastic step of developing a more typical cat or do like killer, a kind of cat-ape or dog-ape, by the simple process of enlarging the teeth and nails into savage fang-like and claw-like weapons. But this would have put the ancestral ground-ape into direct competition with the already highly specialised cat and dog killers. It would have meant competing with them on their own terms, and the outcome would no doubt have been disastrous for the primates in question. (For all we know, this may actually have been tried and failed so badly that the evidence has not been found.) Instead, an entirely new approach was made, using artificial weapons instead of natural ones, and it worked.
From tool-using to tool-making was the next step, and alongside this development went improved hunting techniques, not only in terms of weapons, but also in terms of social co-operation. The hunting apes were pack-hunters, and as their techniques of killing were improved, so were their methods of social organisation. Wolves in a pack deploy themselves, but the hunting ape already had a much better brain than a wolf and could turn it to such problems as group communication and co-operation. Increasingly complex maneuvers could be developed. The growth of the brain surged on.
Essentially this was a hunting-group of males. The females were too busy rearing the young to be able to play a major role in chasing and catching prey. As the complexity of the hunt increased and the forays became more prolonged, it became essential for the hunting ape to abandon the meandering, nomadic ways of its ancestors. A home base was necessary, a place to come back to with the spoils, where the females and young would be waiting and could share the food. This step, as we shall see in later chapters, has had profound effects on many aspects of the behaviour of even the most sophisticated naked apes of today.
So the hunting ape became a territorial ape. His whole sexual, parental and social pattern began to be affected. His old wandering, fruit-plucking way of life was fading rapidly. He had now really left his forest of Eden. He was an ape with responsibilities. He began to worry about the prehistoric equivalent of washing machines and refrigerators. He began to develop the home comforts—fire, food storage, artificial shelters. But this is where we must stop for the moment, for we are moving out of the realms of biology and into the realms of culture. The biological basis of these advanced steps lies in the development of a brain large and complex enough to enable the hunting ape to take them, but the exact form they assume is no longer a matter of specific genetic control. The forest ape that became a ground ape that became a hunting ape that became a territorial ape has become a cultural ape, and we must call a temporary halt.