The Revolutionary Birth of Man
The Epoch of the Dinosaurs—the Mesozoic (850-65 million year ago)
Why did the Disnosaurs Disappear?
The Cosmic Terrorist- or
How Not to Make a Hypothesis
The Revolutionary Birth of Man
The Role of Toolmaking
Social Organisation
Hypotheses on Human Development
Engels and Human Origins
Can Apes Make Tools?
Humans and Language
The continental mass, Pangaea, created through the collision of the continents in the Palaeozoic era, remained intact for about 100 million years. This gave rise to a new set of tectonic, climatic and biological conditions. Then in the Mesozoic era the process turned into its opposite. The super-continent began to break up. Vast glaciers covered the southern parts of Africa-America-Australia and Antarctica. During the Triassic (250-205 million years ago) dinosaurs evolved on the land and pleisiosaurus and ichthyosaurus in the sea, while the winged reptile pterosaurus later took to the air. Mammals evolved from the thraspid reptiles, but they developed very slowly. The explosive growth of the dinosaurs which dominated other vertebrate terrestrial life-forms did not permit a major development of mammals. They remained small both in size and numbers for millions of years, eclipsed by the shadow of their giant contemporaries, searching for food at night.
The Jurassic (205-145 million years ago) saw a major climatic change marked by the retreat of the glaciers, leading to a rise in global temperature towards the end of the period. The level of the seas rose by at least 270 meters during the Mesozoic, reaching almost double the present average level.
It takes a long time to fragment a supercontinent. The break-up of Pangaea began at the beginning of the Jurassic (180 million years ago) and the last continent was not separated until the early Cenozoic (40 million years ago). The first separation was on an east-west axis, where the creation of the Tethys Ocean split Pangaea into Laurasia in the North and Gondwanaland in the South. In turn, Gondwanaland split into three parts in the east—India, Australia and Antarctica. During the late Mesozoic a North-South split appeared, creating the Atlantic Ocean which separated north America from Laurasia and South America from Africa. India moved to the north and collided with Asia, while Africa also moved to the north and partly collided with Europe after the destruction of the Tethys Ocean. Of this mighty ocean, only a tiny part remained as the Mediterranean Sea. In the Pacific, Atlantic and Indian Oceans, periods of rapid expansion of the sea floor assisted the movement of the continental fragments.
Throughout the Mesozoic, dinosaurs were the dominant group of vertebrates. Despite the separation of the continents, they were firmly established all over the world. But at the end of this period—65 million years ago—there was a new period of mass extinctions, in which the dinosaurs vanished from the face of the earth. Most of the terrestrial, marine and flying reptiles (dinosaurs, ichthyosaurs and pterosaurs) were wiped out. Of the reptiles, only the crocodiles, snakes, turtles and lizards survived. This spectacular elimination of species was not confined to the dinosaurs, however. In fact, about one-third of all living species became extinct, including the ammonites, bellemnites, some plants, bryozoa, bivalve molluscs, echinoids and others.
The remarkable success of the dinosaurs was a result of their perfect adaptation to the existing conditions. The total population was at least as big as that of mammals today. At present, everywhere in the world, there is a mammal, big or small, occupying every available ecological space. We can be sure that 70 million years ago, those spaces were occupied by an immense variety of dinosaurs. Contrary to the common impression of the dinosaurs as huge, lumbering creatures, they existed in all sizes. Most were relatively small, many walked upright on their hind legs, and could run very fast. Many scientists now believe that at least some of the dinosaurs lived in groups, looked after their young, and possibly even hunted in packs. The Mesozoic-Cenozoic boundary (65 million years ago) represents yet another revolutionary turning-point in the evolution of life. A period of mass extinction prepared the way for a huge evolutionary leap forward, opening the way for the rise of the mammals. But before we deal with this process, it is worth while considering the question of why the dinosaurs disappeared.
Why did the Dinosaurs Disappear?
This question has been hotly debated in recent years, and, despite very confident claims, particularly on behalf of the meteorite-catastrophe theory, is still not decisively resolved. There are in fact many theories which have attempted to explain a phenomenon which, both because of its spectacular appearance and because of its implications for the emergence of our own species, has captured the popular imagination in a unique way. Nevertheless, it is necessary to remind ourselves that this was not a unique event in the chain of evolution. It was not the only mass extinction, or the biggest, or necessarily the one with the most far-reaching evolutionary consequences.
The theory which currently enjoys most support and which certainly has been given the most sensational publicity is based on the assertion that the impact of a huge meteorite falling somewhere on the earth’s surface caused an effect rather similar to the "nuclear winter" which would follow a major nuclear war. If the impact were sufficiently large, it would throw great quantities of dust and debris into the atmosphere. The dense clouds thus formed would prevent the sun’s rays from reaching the earth’s surface, resulting in a prolonged period of darkness and falling temperatures.
There is empirical evidence to suggest that some kind of explosion took place, which may have been caused by a meteorite. The theory has gained ground in recent years with the discovery of a thin layer of clay amongst fossil remains, which would be consistent with the effect of dust produced by such a large impact. The idea has, for example, seemingly been accepted by Stephen J. Gould. Nevertheless, there are questions which have still to be answered. First of all, the dinosaurs did not disappear overnight, or even in a few years. In fact, the extinction occurred over several million years—a very short time in geological terms, but sufficiently long to cast some doubt on the idea of a meteoric catastrophe.
While the meteorite hypothesis cannot be ruled out, it has one major disadvantage. As we have pointed out, there have been many mass extinctions along the evolutionary road. How is this to be explained? Do we really have to resort to an external phenomenon such as a sudden meteor impact to do so? Or does the rise and fall of species have something to do with tendencies that are inherent within the process of evolution itself? Even at the present time, we can observe the phenomenon of the rise and fall of animal populations. Only recently have we come close to understanding the laws which govern this complex process. By looking for explanations that lie outside the given phenomenon, we run the risk of abandoning the search for a real understanding. Moreover, a solution which seems attractive because it removes all difficulties at a stroke can create even greater difficulties than the ones it was alleged to have solved.
Several other suggestions have been put forward. The period under consideration was characterised by widespread volcanic activity. This, and not a meteorite impact, could well have caused a change in the climate which the dinosaurs were unable to cope with. It has also been suggested that the disappearance of the dinosaurs was connected with competition from the mammals. There is a parallel here with the disappearance of most of the original marsupial population of South America under pressure from the mammals from the North. Indeed, it is possible that the extinction of these creatures was the result of a combination of these circumstances—volcanic activity, destruction of the existing environment, excessive specialisation, and competition for reduced food resources by a species better-equipped to cope with the changed conditions. It is unlikely that this particular controversy will be resolved in the near future. What is not in dispute is that, at the end of the Mesozoic some fundamental change ended the domination of the dinosaurs. The main thing is that it is not necessary to introduce external factors to explain this phenomenon:
"‘You don’t have to look for sunspots, climatic upheavals or any other weird explanation to account for the disappearance of the dinosaurs,’ said Lovejoy. ‘They did fine as long as they had the world to themselves, as long as there was no better reproductive strategy around. They lasted more than a hundred million years; humans should as well. But once a breakthrough adaption was made, once dinosaurs were confronted by animals that could reproduce successfully three or four times as fast as they could, they were through.’" (28)
The Cosmic Terrorist—or How Not to Make a Hypothesis
The problem becomes clear the moment we pose the question in the following way: very well, let’s accept that the extinction of the dinosaurs was caused by an accident in the form of a sudden meteorite impact. How do we explain all the other mass extinctions? Were they all caused by meteorites? The question is not as pointless as it might seem. Attempts have indeed been made to show that all the large-scale extinctions were the result of periodic storms of meteorites from the asteroid belt. This is the substance of the so-called "Nemesis theory" put forward by Richard Muller of the University of California.
Certain palaeontologists (Raup and Sepkoski) have claimed that mass extinctions occur at regular intervals of approximately 26 million years. However, others basing themselves on the same evidence have found no such regularity in this phenomenon. There is a similar disagreement among geologists, some of whom claim to see evidence of regular periodicity in the occurrence of big craters, while others disagree. In short, there is no conclusive evidence either for the idea of regular intervals between mass exterminations or of regular bombardment of the earth by comets or meteorites.
Such a field lends itself easily to the most arbitrary and senseless speculations. Moreover, it is precisely such sensational "theories" which tend to get most publicity, irrespective of their scientific merit. The "Nemesis" theory is a case in point. If we accept, as Muller does, that mass exterminations occur regularly every 26 million years, and if we further accept, as he does, that mass extinctions are caused by meteorite storms, then it must follow that the earth must have been visited by meteorites every 26 million years, as regular as the clock.
The difficulty in such a notion is quite clear—even to Muller, who writes:
"I found it incredible that an asteroid would hit precisely every 26 million years. In the vastness of space, even the Earth is a very small target. An asteroid passing close to the sun has only slightly better than one chance in a billion of hitting our planet. The impacts that do occur should be randomly spaced, not evenly strung out in time. What could make them hit on a regular schedule? Perhaps some cosmic terrorist was taking aim with an asteroid gun. Ludicrous results require ludicrous theories."
And Muller went on to make up precisely such a ludicrous theory, in order to justify the preconceived idea that all mass extinctions were indeed caused by meteorite impacts, and that these happen regularly every 26 million years. He describes a heated argument with Luis Alvarez, the originator of the original theory that the dinosaurs were wiped out by an asteroid crashing into the earth, who was sceptical about Muller’s ideas. The following extract from this dialogue gives us an interesting insight into the methodology whereby certain hypotheses are born:
"‘Suppose someday we found a way to make an asteroid hit the Earth every 26 million years. Then wouldn’t you have to admit that you were wrong, and that all the data should have been used?’
"‘What is your model?’ he demanded. I thought he was evading my question.
"‘It doesn’t matter! It’s the possibility of such a model that makes your logic wrong, not the existence of any particular model.’
"There was a slight quiver in Alvarez’s voice. He, too, seemed to be getting angry. ‘Look, Rich,’ he retorted, ‘I’ve been in the data-analysis business a long time, and most people consider me quite an expert. You just can’t take a no-think approach and ignore something you know.’
"He was claiming authority! Scientists aren’t allowed to do that. Hold your temper, Rich, I said to myself. Don’t show him you’re getting annoyed.
"‘The burden of proof is on you,’ I continued, in an artificially calm voice. ‘I don’t have to come up with a model. Unless you can demonstrate that no such models are possible, your logic is wrong.’
"‘How could asteroids hit the Earth periodically? What is your model?’ he demanded again. My frustration brought me close to the breaking point. Why couldn’t Alvarez understand what I was saying? He was my scientific hero. How could he be so stupid?
"Damn it! I thought. If I have to, I’ll win this argument on his terms. I’ll invent a model. Now my adrenaline was flowing. After another moment’s thought, I said: ‘Suppose there is a companion star that orbits the sun. Every 26 million years it comes close to the Earth and does something, I’m not sure what, but it makes asteroids hit the Earth. Maybe it brings the asteroids with it.’"
The completely arbitrary nature of the method used to arrive at a hypothesis without the slightest basis in fact is glaringly obvious. With such an approach, we really leave the realm of science and enter that of science fiction, where, in the words of the old song, "anything goes." In fact, Muller himself is honest enough to confess that "I hadn’t meant my model to be taken that seriously, although I had felt that my point would be made if the model could withstand assault for at least a few minutes." (29) But we live in an age of credulity. The "Nemesis" theory, which is quite clearly not a scientific model, but an arbitrary guess, is now being taken with the utmost seriousness by many astronomers who are sweeping the skies, busily searching for clues of the existence of this invisible "death-star," this cosmic terrorist who, having made short work of the dinosaurs, will one day return to the scene of the crime, and finish us all off!
The problem here is one of method. When Napoleon asked Laplace where God fitted into his mechanical scheme of the universe, he gave the famous reply: "Sire, je na’ai pas besoin de cette hypothèse." ("Sire, I have no need for that hypothesis"). Dialectical materialism sets out to discover the inherent laws of motion of nature. Whereas accident plays a role in all natural processes, and it cannot, in principle be excluded that, for example, the extinction of the dinosaurs was caused by a stray asteroid, it is completely misleading and counterproductive to seek the causes of mass exterminations in general in external phenomena, wholly unrelated to the processes under consideration. The laws which govern the evolution of the species must be sought for and found in the process of evolution itself, which includes both long periods of slow change, but also other periods where change is enormously accelerated, giving rise both to mass exterminations of some species and the emergence and strengthening of new ones.
It is the lack of ability to grasp the process as a whole, to understand its contradictory, complex, non-linear character—that is to say, the lack of a dialectical approach—which leads to these arbitrary attempts to solve problems by recourse to extraneous factors, like a deus ex machina, the proverbial rabbit pulled out of a conjurer’s hat. Along this road lies only the deadest of dead-ends. Moreover, the extraordinary propensity for the acceptance of the wildest scenarios—almost all involving the idea of some impending cosmic catastrophe, signifying, at the very least, the end of the world—is something which tells us a lot about the general psychological make-up of society in the last decade of the 20th century.
The Revolutionary Birth of Man
The era known as the Cenozoic begins with the mass extinctions 65 million years ago and has continued right up to the present. During this era, the continents continued to drift, separate and collide. This created new environmental conditions. In the first 20 million years, temperatures continued to rise, and a tropical zone appeared, in which conditions in Britain, for example, resembled those of a Malaysian jungle. The most important development in evolution in this era was the extraordinarily rapid rise of the mammals, which took over the environments vacated by the reptiles. By 40 million years ago, primates, elephants, pigs, rodents, horses, sea cows, porpoises, whales and bats, as well as most orders of modern birds and many families of plants, had all appeared.
The rise of the mammals might be seen as a kind of triumphal procession, in which evolution progresses ever upwards, in an unbroken line, culminating finally in the birth of humankind, the crowning glory of creation. But this was far from the case. Evolution was never a straight line, as we have seen. Periods of intense growth were, in this period also, followed by dramatic reversals, death and extinction. The two main periods of extinction are linked with sharp environmental changes. By 40-30 million years ago, we observe the beginnings of a cooling process. Temperature fell continuously for the next 25 million years, only stabilising at its present level 5 million years ago. That period witnessed the first recent period of extinctions affecting mammals.
The primates, the ancestors of apes and of humans, were spread all over the world. The period of extinction of the dinosaurs had an effect on many of these families. The new environmental conditions led to the development of a new species—the proto-apes, better adapted to the changed conditions. It is worth mentioning that the new conditions mainly influenced Africa and Euro-Asia, and not America. By this time, Antarctica reached the South Pole and began to be covered in ice. For the next 10-20 million years, there was a further period of explosive growth of mammals—the biggest ever—in which many species of apes appeared. However, the basic design of the apes remained unchanged throughout this period, until a new sharp climatic shift brought about a transformation. There are considerable disagreements among palaeontologists on the question of when and how the hominids separated from the apes. There are indications from bones that as far back as 14 million years ago there was already a species which resembled modern apes. Scientists believe that these bones belong to a species which lived both in Africa and Euro-Asia from 14-7 million years ago. It appears to have been a very successful species, and represents the common ancestor of humans, apes and gorillas. Then, 10-7 million years ago, there was a new and dramatic environmental change.
Antarctica was already covered by glaciers. Now the ice-sheet spread, not only in the South, but in the North, where it covered Alaska, North America, and North Europe. Since more and more water was trapped in the ice, the sea-level began to decline. It has been estimated that the fall in sea-levels was more than 150 metres at that time. As a result, new land-masses appeared, joining the continents; land bridges were formed connecting Europe and Africa, Asia and America, Britain and Europe, thus making possible further migrations of species. The Mediterranean Sea completely evaporated. The climate around the equator became very dry, causing extensive desertisation, together with a massive decline of jungles and forests, and the emergence of vast expanses of savannahs and open land. By this time, Asia was separated from Africa by deserts, thus cutting off the African apes from their Asian cousins. Inevitably, this was another period of extinction and death. But it was equally a period of the birth of new species. At a certain point, possibly 7 million years ago, the development of mammals resulted in the emergence of the first hominids (human-like primates).
It is now generally accepted that humankind originated in Africa. By 5.3 million years ago, the Mediterranean assumed its present form, and a new species of ape developed in Africa, which, in the course of a million years, developed in three different directions, giving rise eventually to apes, hominids and gorillas. The separation of these three branches occurred about 4-5 million years ago as a result of environmental pressure in Eastern Africa. The spread of the glaciers to South Africa resulted in a dramatic change in Eastern Africa—severe depletion of forests, because of reduced rainfall and a generally drier climate. This was probably the driving-force which led to the separation of the three species of proto-apes. Hitherto, they had lived in trees. Now they had three options:
1) Part of them remained in the forests. These must have been the most skilful, strongest and most successful in extracting food from limited sources. However, the decline of the forest habitat must have severely depleted their numbers. The remnant of this branch is represented by the modern gorillas.
2) Another group, forced to move to the margins of the forests, with fewer trees and less food resources, eventually were forced to increase their food-gathering range by moving on the ground, while remaining near the trees for protection. This group is represented by the modern chimpanzees.
3) A third group, probably made up of the weaker and less skilful section of the species, were compelled by intense competition for scarce food resources to move out of the forest altogether. They were thus forced not only to move on the ground, but to cover long distances in order to find the food necessary for their survival. They were compelled to develop an entirely new way of living, radically different to that of other primates.
Environmental pressures in Asia caused by climatic changes also drove some groups of monkeys to the fringes of the forests. These developed into the modern baboons, which move on the ground in search of food, but return to the trees for protection. Primates exhibit a variety of modes of locomotion. The tarsier leaps and clings; the gibbon swings from limb to limb; the orangutan is "four-handed"; the gorilla is a knuckle walker; the monkey is a true quadruple; only hominids have ventured to become completely bipedal.
"Other specialisations have gone with handedness. If one is going to jump and snatch, one had better be able to judge distances accurately. If not, one will come up empty-handed at best; at worst, one will miss the branch entirely and fall. The way to precise distance judgment is via binocular vision: focusing two eyes on an object to provide depth perception. That requires that the eyes be set in the front of the skull and facing forward, not on the sides of the head, as a squirrel’s eyes are. Primate ancestors developed such vision. Their skulls become rounded to accommodate the new position of the eyes, and with that change in shape came an enlargement of the skull capacity and the opportunity to have a larger brain. At the same time, the jaw became smaller. With hands, an animal does not have to do all its foraging and hunting with its teeth. It can afford a shorter jaw and fewer teeth. Modern apes and monkeys—and humans—have sixteen teeth in each jaw. Their ancestors had as many as twenty two." (30)
The psychologist Jerome Bruner in his writings on the mental development of children, has stressed that skilled behaviour has much in common with language production on the one hand and problem-solving on the other. The simplest skills almost all involve the use of the hand or hands and the visual guidance. On the development of the human hand, Bruner writes the following:
"The hands of man are a slow-growing system, and it is many years before humans can exhibit the kind of manual intelligence that has distinguished our species from others—the using and making of tools. Indeed, historically, the hands were regarded even by students of primate evolution as of no particular interest. Wood Jones would have us to believe that there was little morphological difference between the monkey hand and that of man, but that the difference was in the function to which they were put by the central nervous system. Yet, as Clark and Napier have pointed out, it is the evolutionary direction of morphological change in the hand, from tree shrews through New World monkeys through Old World monkeys to man, that should reveal how the function of the hand has changed and, with it, the nature of the implementation of human intelligence.
"That change has been steadily in the direction of a very special form of despecialisation. The hand is free from its locomotor function, from its brachiating function, and from such specialised requirements as were answered by claws and by exotic forms of finger pads. Becoming more despecialised in function means becoming more varied in the functions that can be fulfilled. Without losing its capacity for phalangeal divergence needed for weight-wearing, convergence for cupping food, prehensility for holding and climbing, or opposability—all part of an early primate heritage—the hand in the later primate evolution achieves several new functional capacities while undergoing appropriate morphological change as well. A combined capacity for power and precision grip is added.
"The flexibility of the palm and thumb increases through changes in the hamate and trapezium bones in their articulation. The thumb lengthens and its resting angle to the hand increases. The terminal phalanges broaden and strengthen, particularly the thumb. Napier may exaggerate when he says, ‘The present evidence suggests that the stone implements of early man were as good (or as bad) as the hand that made them.’ For surely, initially stupid hands become clever when employed in a clever programme devised by the culture." (31)
The first hominid fossils were found in East Africa, and belong to the species known as Australopithecus Afarensis, which lived around 3.5-3.3 million years ago. These ape-like creatures were able to walk upright, possessed hands with thumbs fully opposed to the fingers, and therefore capable of manipulating tools. Their cranial capacity was larger than other apes (450 ccs.). As yet, no tools have been found in connection with these early hominids, but are clearly in evidence when we come to the first clearly identifiable human species, the aptly-named homo habilis ("handyman"), which walked upright, had a height of 1.20 metres and had a brain capacity of 800 cubic centimetres.
At what point does the real separation of humans from hominid apes take place? Palaeontologists have argued for a long time over this question. The answer was given by Engels in his masterly essay The Part Played by Labour in the Transition of Ape to Man. But it was already anticipated by Marx and Engels much earlier in their pioneering work, The German Ideology, written in 1845:
"Men can be distinguished from animals by consciousness, by religion or anything else you like. They themselves begin to distinguish themselves from animals as soon as they begin to produce their means of subsistence, a step which is conditioned by their physical organisation. By producing their means of subsistence men are indirectly producing their material life." (32)
In an extremely superficial attempt to discredit the materialist view of the origin of the human species, it is often stated that humans are not the only animals to "use tools." This argument is completely hollow. While many animals (not only monkeys and chimpanzees, but even some birds and insects) may be said to use "tools" for certain activities, these are limited to whatever natural materials they find to hand—sticks, stones etc. Moreover, such use either consists of accidental activity, as when a monkey throws a stick to dislodge fruit from a tree, or limited actions which may be highly complex, but are entirely the result of genetic conditioning and instinct. The actions are always the same. There is no question of intelligent planning, foresight or creativity, except to a very limited degree in the higher species of mammals, but the most advanced of the apes have nothing resembling the productive activity of even the most primitive hominids.
The essential point is not that humans "use tools." It is the fact that humans are the only animals that make tools, and not as an isolated or accidental activity, but as the essential condition for their existence upon which everything else depends. Thus, although from a genetic point of view humans and chimpanzees are almost identical, and the behaviour of these animals in some respects appears remarkably "human," the most intelligent chimpanzee is quite incapable of making even the most rudimentary stone tools produced by homo erectus, a creature standing on the evolutionary threshold of humanity.
In his most recent book, The Origin of Humankind, Richard Leakey, makes this point:
"Chimpanzees are adept tool users, and use sticks to harvest termites, leaves as sponges, and stones to crack nuts. But—so far, at any rate—no chimpanzee in the wild has ever been seen to manufacture a stone tool. Humans began producing sharp edged tools 2.5 million years ago by hitting two stones together, thus beginning a trail of technological activity that highlights human prehistory." (33)
Compare these lines to what Engels wrote in 1876:
"Many monkeys use their hands to build nests for themselves in the trees or even, like the Chimpanzee, to construct roofs between the branches for protection against the weather. With their hands they seize hold of clubs to defend themselves against enemies, or bombard the latter with fruits and stones. In captivity, they carry out with their hands a number of simple operations copied from human beings. But it is just here that one sees how great is the gulf between the undeveloped hand of even the most anthropoid of apes and the human hand that has been highly perfected by the labour of hundreds of thousands of years. The number and general arrangement of the bones and muscles are the same in both; but the hand of the lowest savage can perform hundreds of operations that no monkey’s hand can imitate. No simian hand has ever fashioned even the crudest stone knife." (34)
Nicholas Toth has spent many years attempting to reconstruct the methods by which early humans produced tools, and has come to the conclusion that even the most basic processes of flaking stone requires not only considerable care and manual dexterity, but also a degree of foresight and planning.
"To work efficiently, the stone knapper has to choose a rock of the correct shape, bearing the correct angle at which to strike; and the striking motion itself requires great practice in order to deliver the appropriate amount of force in the right place. ‘It seems clear that early tool-making proto-humans had a good intuitive sense of the fundamentals of working stone,’ Toth wrote in a paper in 1985. ‘There’s no question that the earliest toolmakers possessed a mental capacity beyond that of apes,’ he recently told me. ‘Toolmaking requires a coordination of significant motor and cognitive skills.’" (35)
There is a close correlation between the hand, the brain, and all the other organs of the body. The part of the brain connected with the hands is vastly greater than that which is connected with any other part of the body. Darwin already grasped the fact that the development of certain parts of the organism are linked with the development of other parts which apparently have no relation to them. He called this phenomenon the law of the correlation of growth. The development of manual dexterity through labour provided the stimulus for a rapid development of the brain.
The development of humankind was not an accident, but the result of necessity. The upright stance of early hominids was necessary to allow them to move freely on the savannah in search of food. The head had to be positioned at the top of the body in order to detect the presence of predators, as we see in some other savannah-dwelling animals, such as the meerkat. Limited food sources created the necessity to gather and transport, which was the driving force for the development of the hand.
Apes were not built to walk on two legs and do so rather clumsily. The anatomy of even the earliest hominids reveal a bone structure clearly adapted to upright walking. The upright posture has severe disadvantages in many respects. It is impossible to run as fast on two legs as on four. In many ways, bipedalism is an unnatural posture, which explains the prevalence of back-pains which have plagued the human animal from the cave to the present. The great advantage of bipedalism is that it freed the hands for labour. This was humanity’s great leap forward. Labour is, together with nature, the source of all wealth. But, as Engels points out, it is infinitely more than this:
"It is the primary basic condition for all human existence, and this to such an extent that, in a sense, we have to say: labour created man himself."
The development of the hand through labour is closely connected to the development of the body as a whole.
"Thus the hand is not only the organ of labour, it is also the product of labour. Only by labour, by adaptation to ever new operations, by inheritance of the thus acquired special development of muscles, ligaments, and, over longer periods of time, bone as well, and by the ever-renewed employment of these inherited improvements in new, more and more complicated operations, has the human hand attained the high degree of perfection that has enabled it to conjure into being the pictures of Raphael, the statues of Thorwaldsen, the music of Paganini.
"But the hand did not exist by itself. It was only one member of an entire, highly complex organism. And what benefited the hand, benefited also the whole body it served." (36)
The same thing applies to language. Even though apes are capable of producing a range of sounds and gestures which may be seen as a kind of embryonic "language," all attempts to teach them to talk have ended in failure. Language, as Engels explains, is a product of collective production, and can only arise in a species the life-activity of which depends exclusively on co-operation in order to produce tools, a complex process which must be consciously learnt and passed on from one generation to the next. On this, Noam Chomsky remarks:
"Anyone concerned with the study of human nature and human capacities must somehow come to grips with the fact that all normal humans acquire language, whereas acquisition of even its barest rudiments is quite beyond the capacities of an otherwise intelligent ape."
In recent times, it has become customary to try to show that language is not peculiar to humans. While there is no doubt that systems of communication exist among animals, it is entirely incorrect to describe this as language. Human speech arises from human society and human co-operative productive activity, and is qualitatively different to any other system of communication in the animal world, even the most complex.
"Human language appears to be a unique phenomenon, without significant analogue in the animal world. If this is so, it is quite senseless to raise the problem of explaining the evolution of human language from more primitive systems of communication that appear at lower levels of intellectual capacity."
And again:
"As far as we know, possession of human language is associated with a specific type of mental organisation, not simply a higher degree of intelligence. There seems to be no substance to the view that human language is simply a more complex instance of something to be found elsewhere in the animal world. This poses a problem for the biologist, since, if true, it is an example of true ‘emergence’—the appearance of a qualitative different phenomenon at a specific stage of complexity of organisation" (37)
The rapid expanse in brain size brought additional problems, especially in relation to child-birth. Whereas a newborn ape has a brain size of 200 cubic centimetres—about half that of an adult—that of a human baby (385 cubic centimetres) is only about a quarter of the size of the adult human brain (about 1350 cubic centimetres). The form of the human pelvis, adapted to walking in an upright position limits the size of the pelvic opening. Thus, all human babies are born "prematurely," as a result of the large brain and the restrictions imposed by the biological engineering of bipedalism.
The complete helplessness of the newborn human baby is evident in comparison with any other species of higher mammals. It has been suggested by Barry Bogin, a biologist at the University of Michigan, that the slow rate of bodily growth in human infants, as compared to apes, is connected with the long time needed to absorb the complex rules and techniques of human society. Even the difference in body-size between children and adults helps to establish a teacher-pupil relationship, where the young learn from the old, whereas among the apes rapid growth soon leads to physical rivalry. When the long process of learning is complete, the body catches up with a sudden leap in growth during adolescence.
"Humans become human through intense learning not just of survival skills but of customs and social mores, kinship and social laws—that is, culture. The social milieu in which helpless infants are cared for and older children are educated is much more characteristic of humans than it is of apes." (38)
Life on the open savannah with a multitude of predators was a dangerous affair. Humans are not strong animals, and the early hominids were much smaller than modern humans. They possessed neither strong claws nor powerful teeth, nor could they outrun lions and other four-footed predators. The only way to survive was by developing a highly organised and co-operative community for the collective exploitation of scarce food resources. But the decisive step was without doubt the manufacture of artefacts, beginning with the stone scrapers, used for a variety of purposes. Despite their deceptively simple appearance, these were already highly sophisticated and versatile tools, the production of which implies a significant degree of organisation, planning, and at least the elements of a division of labour. Here we have the real beginnings of human society. In the words of Engels:
"As already said, our simian ancestors were gregarious; it is obviously impossible to seek the derivation of man, the most social of all animals, from non-gregarious immediate ancestors. The mastery over nature, which begins with the development of the hand, with labour, widened man’s horizon at every new advance. He was continually discovering new, hitherto unknown, properties of natural objects. On the other hand, the development of labour necessarily helped to bring the members of society closer together by multiplying cases of mutual support, joint activity, and by making clear the advantage of this joint activity to each individual. In short, men in the making arrived at the point where they had something to say to one another. The need led to the creation of its organ; by modulation the undeveloped larynx of the ape was slowly but surely transformed for ever more developed modulation, and the organs of the mouth gradually learned to pronounce one articulate letter after another." (39)
The production of tools, the beginnings of a division of labour, originally between men and women, the development of language, and a society based on co-operation—these were the elements which marked the real emergence of humankind. This was not a slow, gradual process, but represents yet another revolutionary leap, one of the most decisive turning-points in evolution. In the words of the palaeontologist Lewis Binford, "Our species had arrived—not as a result of gradual, progressive processes but explosively in a relatively short period of time." (40)
The relation between labour and all the other factors was explained by Engels:
"First labour, after it, and then with it, articulate speech—these were the two most essential stimuli under the influence of which the brain of the ape gradually changed into that of man, which for all its similarity to the former is far larger and more perfect. Hand in hand with the development of the brain went the development of its most immediate instruments—the sense organs. Just as the gradual development of speech is necessarily accompanied by a corresponding refinement of the organ of hearing, so the development of the brain as a whole is accompanied by a refinement of all the senses. The eagle sees much farther than man, but the human eye sees considerably more in things than does the eye of the eagle. The dog has a far keener sense of smell than man, but it does not distinguish a hundredth part of the odours that for man are definite features of different things. And the sense of touch, which the ape hardly possesses in its crudest initial form, has been developed only side by side with the development of the human hand itself, through the medium of labour."
The earliest hominids had a predominantly vegetarian diet, although the use of even the most primitive tools like digging-sticks gave them access to supplies of food not available to other apes. This diet was supplemented by small quantities of meat, obtained mainly by scavenging. The real breakthrough came when the production of tools and weapons permitted humans to pass over to hunting as the primary source of food. The consumption of meat undoubtedly led to a rapid further increase in brain size:
"A meat diet," writes Engels, "contains in an almost ready state the most essential substances required by the organism for its metabolism. It shortened the time required, not only for digestion, but also for the other vegetative bodily processes corresponding to those of plant life, and thus gained further time, material, and desire for the active manifestation of animal life in the proper sense of the term. And the further that man in the making became removed from the plant kingdom, the higher he rose also above animals. Just as becoming accustomed to a plant diet side by side with meat converted wild cats and dogs into the servants of man, so also adaptation to a flesh diet, side by side with a vegetable diet, considerably contributed to giving bodily strength and independence to man in the making. The most essential effect, however, of a flesh diet was on the brain, which now received a far richer flow of the materials necessary for its nourishment and development, and which therefore could become more rapidly and perfectly developed from generation to generation." (41)
Exactly the same point is made by Richard Leakey, who relates it to a fundamental change in social organisation. In most other primates, there is fierce competition between males to mate with the females. This is reflected in the very considerable differences in body size between, say, male and female savannah baboons. Such a difference can be seen in the earliest hominids, such as Australopithecus Afarensis. This suggests a social structure closer to the apes than to humans. In other words, physical adaptations such as bipedalism, vital as it undoubtedly was as a precondition for human evolution, does not yet entitle us, contrary to what Richard Leakey suggests, to characterise these early hominids as humans.
Among savannah baboons, the males (who are twice the size of the females) leave the troop as soon as they reach maturity, and join another troop, where they immediately enter into competition with the established males for access to the females. Thus, in Darwinian terms, these males have no (genetic) reason for co-operating with each other. Among chimpanzees, on the other hand, for reasons not yet understood, the males remain in the group where they were born, and the females migrate. The male chimpanzees, being genetically related, have a Darwinian reason to co-operate, which they do, both to defend the group against outsiders, and even occasionally combining to hunt a monkey to supplement their diet. The difference in body-size between male and female chimpanzees is only 15-20%, reflecting the predominantly co-operative nature of this society.
Whereas the difference in size between male and female members of the Australopithecus Afarensis group was so great that they were at first thought to be fossils from two entirely different species, the situation is radically different when we come to the earliest members of the human species, where males were no more than 20% larger than females, as with chimpanzees, our closest genetic relatives. On this, Leakey remarks:
"As the Cambridge anthropologists Robert Foley and Phyllis Lee have argued, this change in body-size differential at the time of the origin of the genus Homo surely represents a change in social organisation, too. Very probably, early Homo males remained with their natal groups with their brothers and half brothers, while the females transferred to other groups. Relatedness, as I’ve indicated, enhances co-operation among the males.
"We can’t be certain what prompted this shift in social organisation: enhanced co-operation among males must have been strongly beneficial for some reason. Some anthropologists have argued that defence against neighbouring troops of Homo became extremely important. Just as likely, and perhaps more so, is a change centred on economic needs. Several lines of evidence point to a shift in diet for Homo—one in which meat became an important energy and protein source. The change in tooth structure in early Homo indicates meat eating, as does the elaboration of a stone-tool technology. Moreover, the increase in brain size that is part of the Homo package may even have demanded that the species supplement its diet with a rich energy source." (42)
It is well-known that the brain is a metabolically expensive organ, which in modern humans absorbs 20% of energy consumed, despite only amounting 2% of total body weight. The Australian anthropologist Robert Martin has explained that the increase in brain size in early Homo could only have occurred on the basis of an enhanced energy supply, which could only come from meat, with its concentration of calories, proteins and fat. Originally, this would have come from scavenging, and some hunting activity (which, as we know, occurs even among chimpanzees). But later there is little doubt that hunting played an increasing role in providing a more varied and nutritional diet, with far-reaching evolutionary consequences.
Hypotheses on Human Development
In recent years, there has been a fierce controversy about the role of hunting in early human society. There has been a tendency to play down the role of hunting, insisting more on the role of food gathering and scavenging. While this question is still not decisively resolved, it is difficult not to share Leakey’s view that the argument against the hunter-gatherer model of early human society has gone too far. It is also interesting to note the way in which these controversies tend to reflect certain prejudices or social pressures and fads which have nothing whatsoever to do with the issues at stake.
In the early years of the 20th century, the idealist standpoint predominated. Mankind became human thanks to the brain, with its higher thoughts, which propelled all development. Later, the view of "Man the Toolmaker" re-emerged, although in a rather idealised version, in which tools, but not weapons, were said to be the motor-force of evolution. The terrible events of the Second World War then produced a reaction against this, in the form of the theory of "Man the Killer Ape," put forward "possibly because it seemed to explain (or even excuse) the horrible events of the war," as Leakey shrewdly remarks
In the 1960s, there was a great interest in the !Kung San—the incorrectly named "Bushmen" of the Kalahari desert, a group of people living in apparent harmony with their natural environment, and exploiting it in complex ways. This fitted in well with the growing interest in environmental issues in Western society. In 1966, however, the idea of "Man the Hunter" re-emerged strongly at a major anthropological conference in Chicago. This, however, fell foul of the supporters of "Women’s Liberation," in the 1970s. Since hunting is usually seen as a male activity, it was assumed—quite unjustifiably—that to accept it would be somehow to downgrade the role of women in early society. The powerful feminist lobby put forward the hypothesis of "Woman the Gatherer," in which it was argued that the gathering of food, mainly plants, which could be shared, was the basis on which a complex human society evolved.
The central role of women in early society is undeniable, and was clearly explained by Engels in his classic work The Origins of the Family, Private Property and State. However, it is a serious error to read into the record of the past conceptions—or, still worse, prejudices—derived from present-day society. The cause of the emancipation of women will not be advanced a single step by attempting to make the reality of history fit into a pattern which appeals to certain current fashions but is devoid of any real content. We do not make the future of humanity any more hopeful by painting the past in rosier colours. Nor will we encourage people to become vegetarians by denying the fundamental role played by meat-eating, hunting, yes, and even cannibalism, in developing the human brain.
"With all respect to the vegetarians, it has to be recognised that man did not come into existence without a flesh diet, and if the latter, among all peoples known to us, has led to cannibalism at some time or another (the forefathers of the Berliners, the Weletabians or Wilzians, used to eat their parents as late as the tenth century), that is of no consequence to us today." (43)
Similarly, a division of labour must have existed between men and women in the earliest human societies. The mistake, however, is to confuse the division of labour in early society, where neither private property nor the family as we know it today existed, with inequality and the oppression of women in modern class society. In the majority of existing hunter-gatherer societies known to anthropologists, the elements of a division of labour exists, in which the men hunt and the women gather plants for food.
"The camp is a place of intense social interaction, and a place where food is shared"; comments Leakey, "when meat is available, this sharing often involves elaborate ritual, which is governed by strict social rules."
There is good reason to suppose that a similar situation existed in early human society. Instead of the caricature of Social Darwinism, which attempts to extrapolate the laws of the capitalist jungle to cover the whole of human history and prehistory, all the available evidence indicates that the entire basis of early human society was co-operation, collective activity, and sharing. Glynn Isaac of Harvard University made a significant advance in anthropological thinking in a major article published in Scientific American in 1978. Isaac’s food sharing hypothesis emphasises the social impact of collective food gathering and sharing. In a 1982 speech on the centenary of Darwin’s death, he said: "The adoption of food-sharing would have favoured the development of language, social reciprocity and the intellect." In his latest book, The Making of Mankind, Richard Leakey wrote that "the food-sharing hypothesis is a strong candidate for explaining what set early humans on the road to modern man."
The last 2 million years have been characterised by a unique climate cycle. Long periods of intense cooling and glacier advances have been interrupted by short periods of rising temperatures and glacial retreat. Ice ages have an average duration of 100,000 years, whereas the interglacial periods last for approximately 10,000. Under these extreme conditions, mammals were compelled to develop more advanced forms or to disappear. Out of a total of 119 mammalian species living in Europe and Asia 2 million years ago, only nine still survive. The big majority of the rest either developed as more advanced species, or disappeared. Once again, birth and death are inseparably linked in the contradictory, bitter-sweet, dialectical process of evolution.
The last ice age gave way to a new inter-glacial period, which has lasted until the present, but will eventually come to an end. Homo Erectus gave way to a more advanced hominid—Homo Sapiens—about five hundred thousand years ago. The human race (Homo Sapiens Sapiens) represents one evolutionary line from Homo Sapiens, branching off about a hundred thousand years ago. The other line—Homo Sapiens Neanderthalensis—either disappeared or was absorbed around 40,000 years ago. Thus, the human race developed during a period characterised by intense cooling. These conditions represented a severe struggle for survival. However, there were other periods in which conditions improved, stimulating massive growth and waves of human migration. The age of humankind begins to dawn.
How do the ideas of Engels, The Part Played by Labour in the Transition of Ape to Man, stand in the light of the most recent theories of evolution?
One of the foremost modern palaeontologists is Stephen J. Gould. In his book Ever Since Darwin, he gives the following appraisal of Engels’ essay:
"Indeed, the nineteenth century produced a brilliant exposé from a source that will no doubt surprise most readers—Friedrick Engels. (A bit of reflection should diminish surprise. Engels had a keen interest in the natural sciences and sought to base his general philosophy of dialectical materialism upon a ‘positive’ foundation. He did not live to complete his ‘dialectics of nature,’ but he included long commentaries on science in such treatises as the Anti-Dühring.) In 1876, Engels wrote an essay entitled, The Part Played by Labour in the Transition from Ape to Man. It was published posthumously in 1896 and, unfortunately, had no visible impact upon Western science.
"Engels considers three essential features of human evolution: speech, a large brain, and upright posture. He argues that the first step must have been a descent from the trees with subsequent evolution to upright posture by our ground-dwelling ancestors. ‘These apes when moving on level ground began to drop the habit of using their hands and to adopt a more and more erect gait. This was the decisive step in the transition from ape to man.’ Upright posture freed the hand for using tools (labour, in Engels’s terminology); increased intelligence and speech came later." (44)
Despite everything, idealist theories of human evolution still conduct a stubborn rearguard action against materialism, as we see from the following extract from a book published as recently as 1995:
"The force that is likely to have driven our evolution (is)…the process of cultural evolution. As our cultures evolved in complexity, so did our brains, which then drove our bodies towards greater responsiveness and our cultures towards still greater complexity in a feedback loop. Big and clever brains led to more complex cultures and bodies suited to take advantage of them, which in turn led to yet bigger and cleverer brains." (45)
Idealists have repeatedly attempted to assert that man is distinguished from the "lower" animals by his superior intelligence. Evidently, early man, for some unexplained reason, first "became intelligent," then began to speak, use tools, paint pictures and so on. If this were true, one would expect it to be reflected in a significant increase in brain size very early on. However, the fossil record proves that this is not the case.
In the course of the last three decades, there have been a series of tremendous advances in the science of palaeontology, new and exciting fossil discoveries and a new way of interpreting them. According to one recent theory, the first bipedal apes evolved as far back as 7 million years ago. Subsequently, in a process known to biologists as "adaptive radiation," there was a proliferation of bipedal species (that is, species which walked on two legs), with the evolution of many different species of bipedal apes, each adapted to different environmental conditions. About 2-3 million years ago, one of these species developed a significantly larger brain—homo erectus. These were the first hominids to use fire; to use hunting as a significant source of food; to run in the same way as modern humans and to make tools according to a definite preconceived mental plan. Thus, the increase in brain size coincides with the first appearance of tool-making activity, approximately 2.5 million years ago. Thus, for 5 million years, there was no significant expansion of brain size, and then a sudden leap which is clearly identified with the production of tools.
Molecular biology indicates that the earliest hominid species appeared about five million years ago, in the form of a bipedal ape with long arms and curved fingers. The proto-human Australopithecus had a small brain—only 400 cubic centimetres. The qualitative leap took place with homo habilis, who had a brain size of more than 600 cubic centimetres—i.e., an astonishing increase of 50%. The next big advance was with homo erectus, with a brain size of between 850 and 1100 cubic centimetres.
Not until the emergence of homo sapiens about two hundred and fifty thousand years ago does the size of the brain reach modern levels—1350 ccs. Thus, the earliest hominids did not posses large brains. Human evolution was not powered by the brain. On the contrary, the enlarged brain was the product of human evolution, especially the making of tools. The qualitative leap in brain size takes place with homo habilis ("handyman") and is clearly identified with the production of stone tools. In fact a new qualitative leap takes place in the transition from Homo erectus to Homo sapiens. "The human mind appeared on Earth with astonishing suddenness," writes John McCrone. "Just 70,000 years—the merest eye-blink of geological time—covers our ancestors’ transition from smart ape to self-conscious Homo sapiens.
"On the far side of the evolutionary divide stands Homo erectus, a clever beast with a brain almost as big as a modern human’s, a simple tool culture and a mastery of fire—yet mentally still somehow lacking. On our own side stands Homo sapiens with the rituals and symbolic art—the cave paintings, beads and bracelets, decorative lamps and burial graves—that mark the arrival of a self-aware mind. Something sudden and dramatic must have happened, and it is this event that could be the starting point for human consciousness." (46)
It has recently become fashionable to blur the difference between humans and the rest of the animal kingdom to the point where it virtually disappears. In a way, this is preferable to the kind of idealist nonsense of the past. Humans are animals, and share a number of characteristics with other animals, especially our nearest relatives, the apes. The genetic difference between humans and chimpanzees is only about two percent. Yet here too, quantity becomes quality. This two percent represents a qualitative leap which has decisively separated humankind from all other species.
The discovery of the rare species of bonobo chimpanzees, who are even closer to humans than other chimpanzees, has aroused a lot of interest. In their book Kanzi, The Ape at the Brink of the Human Mind, Sue Savage-Rumbaugh and Roger Lewin have given a detailed account of their investigations into the mental capacities of a captive bonobo, Kanzi. There is no doubt that the level of intelligence displayed by Kanzi is significantly higher than that so far seen in non-humans, and in some respects resembles that of a human child. Above all, it shows the existence of the potential for, say, tool-making. This is a powerful argument in favour of the theory of evolution.
Nevertheless, the significant thing about the experiments which attempt to get the bonobo to make a stone tool, is that they were unsuccessful. In the wild, chimpanzees use "tools" such as "fishing sticks" to get termites out of their nest, and even use stones as "anvils" to crack nuts. These operations show a high level of intelligence, and undoubtedly prove that humankind’s nearest relations possess some of the mental prerequisites needed for more advanced activities. But as Hegel once remarked, when we want to see an oak-tree, we are not satisfied if we are shown an acorn instead. The potential for making tools is not the same as actually making them, any more than the mere possibility of winning £10 million on the lottery is the same thing as actually winning. Moreover, this potential, on closer examination turns out to be extremely relative.
Modern chimpanzees occasionally hunt small monkeys. But they do not use weapons or tools for this; they use their teeth. Early humans were able to butcher large carcasses, for which they needed sharp stone tools. No doubt, the earliest hominids used only ready-made implements like sticks for digging up roots. This is just the kind of thing we see with modern chimpanzees. If humans had stuck to a mainly vegetarian diet, there would have been no need to make stone tools. But the ability to make stone tools gave them access to a whole new supply of food. This remains true even if we accept that early humans were not hunters but mainly scavengers. They would still need stone tools to cut through the tough hides of large animals.
The proto-humans of the Oldowan culture in East Africa already possessed quite advanced techniques for making stone tools by the process known as flaking. They selected the right sort of stones, and rejected others; they used the correct angle for striking and so on. All this shows a high level of sophistication and skill, which is absent from the "work" of Kanzi, despite the active intervention of humans aimed at encouraging the bonobo to produce a tool. After repeated efforts, the experimenters were forced to admit that:
"So far Kanzi has exhibited a relatively low degree of technological finesse in each of [the four criteria] compared to that seen in the Early Stone Age record."
And they conclude:
"There is, therefore, a clear difference in the stone-knapping skills of Kanzi and the Oldowan tool-makers, which seems to imply that these early humans had indeed ceased to be apes." (47)
Among other differences separating even the most primitive hominids from the highest of the apes are important changes in body-structure related to the upright stance. The structure of the bonobo’s arms and wrists, for instance, is different from that of humans. The long, curled fingers and short thumb prevent it from gripping a stone effectively enough to strike a powerful glancing blow. This fact has already been pointed out by others:
The chimpanzee’s hand has a fairly well developed opposable thumb, "but it is stubby and meets the forefinger along its side, not at its tip. In the hominid hand, the thumb is much larger and is twisted so that it faces the forefinger. This is a logical concomitant to bipedalism and produces a great increase in dexterity. All hominids seem to have had this kind of hand—even afarensis, the oldest one now known. Its hand is scarcely distinguishable from a modern man’s." (48)
Despite all the efforts to blur the dividing lines, the difference between even the most advanced apes and the most primitive hominids has been established beyond doubt. Ironically, these experiments, intended to disprove the idea of humans as tool-making animals, proved exactly the opposite.
In the same way that attempts have been made to show that tool-making is not a fundamental feature of humanity, so some have tried to show the same thing in relation to language. The part of the brain known as Broca’s area is associated with language, and was thought to be unique to humans. It is now known that this area also exists in other animals. This fact has been used to dispute the idea that the acquisition of language is unique to humans. But this argument seems extremely feeble. The fact remains that no species other than humans depend upon language for their existence as a species. Language is essential to the social mode of production, which is the basis of human society.
In order to prove that other animals can communicate to some extent, it is not necessary to study the behaviour of bonobos. Many of the lower species have quite sophisticated systems of communication—not just mammals, but also birds and insects. Ants and bees are social animals and have highly developed forms of communication. These, however, cannot be taken as implying intelligent thought, or thought at all. They are inborn and instinctive. They also are quite limited in scope. The same actions are repeated endlessly and mechanically and are no less effective for that. But few would regard this as language as we understand it.
A parrot can be taught to repeat whole sentences. Does this mean it can talk? It is fairly clear that, while it can imitate sounds quite well, it has no understanding of what the sounds actually mean. But the conveyance of meaning is the essence of intelligible language. Things are different with the higher mammals. Engels, who was a keen hunter, was not sure to what extent dogs and horses did not partially understand human speech and feel frustrated at not being able to talk. Certainly, the level of understanding shown by the bonobo Kanzi in captivity is quite remarkable. In spite of all this, there are specific reasons why no animal other than humans have a language. Humans alone possess a vocal tract that permits the production of consonants. No other animal can pronounce consonants. Some can make clicking and hissing sounds. In fact, consonants can only be pronounced together with vowels, or they would be reduced to clicks and hisses. The ability to pronounce consonants is a product of walking on two feet, as the study on Kanzi shows:
"Man alone has a vocal tract that permits the production of consonants sounds. These differences between our vocal tract and that of apes, while relatively minor, are significant and may be linked to the refinement of bipedal posture and the associated need to carry the head in a balanced, erect position over the centre of the spine. A head with a large heavy jaw would cause its bearer to walk with a forward list and would inhibit rapid running. To achieve balanced upright posture, it was essential that the jaw structure recede and thus that the sloped vocal tract characteristic of apes become bent at a right angle. Along with the reduction of the jaw and the flattening of the face, the tongue, instead of residing entirely in the mouth, was lowered partially down into the throat to form the back of the oropharynx. The mobility of the tongue permits modulation of the oropharyngeal cavity in a manner that is not possible in the ape, whose tongue resides entirely in the mouth. Similarly, the sharp bend in the supralaryngeal airway means that the distance between the soft palate and the back of the throat is very small. By raising the soft palate, we can block off the nasal passage-ways, permitting us to form the turbulence necessary to create consonants."
Without consonants, we cannot easily distinguish between one word and another. We would just have howls and screeches. These can convey a certain amount of information, but it is necessarily limited:
"Speech is infinitely varied and currently only the human ear can readily find the meaningful units in these infinitely varied patterns. The consonants permit us to accomplish this feat." Human infants are able to categorise consonants in a way similar to adults from a very early age, as anyone who has listened to "baby talk" will know. It consists precisely of constantly repeated experiments with combinations of consonants and vowels—"ba-ba, pa-pa, ta-ta, ma-ma," and so on. Even at this early stage, the human infant is performing a task which no other animal is capable of.
Should we then conclude that the only reason that other animals lack speech is physiological? That would be a serious mistake. The shape of the vocal tract, and the physical ability to combine vowels and consonants are the physical preconditions for human speech, but no more than that. Only the development of the hand, inseparably connected with labour and the need to develop a highly co-operative society, made possible the enlarged brain and language. It seems that the area of the brain related to the use of tools and language have a common origin in the early development of the nervous system of a child, and only become separated from the age of two, when Broca’s area establishes differentiated circuits with the anterior prefrontal cortex. This, in itself, is striking proof of the close link between tool-making and language. Language and manipulative skills developed together, and this evolution is reproduced in the development of human infants today.
Even the earliest hominids of the Oldowan culture had manipulative skills far in advance of the apes. They were not just "upright chimpanzees." The manufacture of even the simplest stone tool is far more complex than it seems. It requires planning and foresight. Homo habilis had to plan ahead. He had to know that at some time in the future he would need a tool, even though, he had no such need in the moment when he discovered the appropriate material. The careful selection of the right kind of stone, and the rejection of others; the searching out of the right angle to strike a blow; this showed a level of thinking ability qualitatively different to that of apes. It seems unlikely that at least the rudiments of language were not present at this stage. But there is further evidence which points in this direction. Humans are unusual in that 90% are right-handed. Such a preference for one hand is not found in other primates. Individual apes may be right-handed or left-handed, but the population as a whole will break down into two equal halves. The phenomenon of handedness is closely connected with manipulative skills and language:
"Handedness is associated with localisation of function to the opposite brain hemisphere. The location of manipulative skills in the left hemispheres of (most) right-handers is accompanied by the location there of language skills, too. The right hemisphere has become specialised for spatial skills."
This phenomenon is absent in Australopithecus, but has been found in the earliest known skulls of homo habilis, the first toolmaker. It is highly unlikely that this is a coincidence. By the time we reach homo erectus, the evidence becomes overwhelming:
"These three lines of anatomical evidence—of the brain, the vocal apparatus, and the capacity for tool-use—provide the principal support for the notion of long, gradual changes on the road to language. Along with these changes in the brain and the vocal apparatus, there occurred concomitant gradual changes in the hand, changes that made it an increasingly suitable instrument for tool construction and use." (49)
The emergence of humankind represents a qualitative leap in evolution. Here, for the first time, matter becomes aware of itself. In place of unconscious evolution, we have the commencement of history. In the words of Frederick Engels:
"With man we enter history. Animals also have a history, that of their descent and gradual evolution to their present position. This history, however, is made for them, and in so far as they themselves take part in it, this occurs without their knowledge and desire. On the other hand, the more that human beings become removed from animals in the narrower sense of the word, the more they make their history themselves, consciously, the less becomes the influence of unforeseen effects and uncontrolled forces on this history, and the more accurately does the historical result correspond to the aim laid down in advance.
"If, however, we apply this measure to human history, to that of even the most developed peoples of the present day, we find that there still exists here a colossal disproportion between the proposed aims and the results arrived at, that unforeseen effects predominate, and that the uncontrolled forces are far more powerful than those set into motion according to plan. And this cannot be otherwise as long as the most essential historical activity of men, the one which has raised them from the animal to the human state and which forms the material foundation of all their other activities, namely the production of their requirements of life, i.e., in our day social production, is above all subject to the interplay of unintended effects from uncontrolled forces and achieves its desired end only by way of exception, but much more frequently the exact opposite…
"Only conscious organisation of social production, in which production and distribution are carried on in a planned way, can lift mankind above the rest of the animal world as regard the social aspect, in the same way that production in general has done this for mankind in the specifically biological aspect. Historical evolution makes such an organisation daily more indispensable, but also with every day more possible. From it will date a new epoch of history, in which mankind itself, and with mankind all branches of its activity, and particularly natural science, will experience an advance that will put everything preceding it in the deepest shade." (50)