Ideas

Peter Watson

• Éditeur: HarperCollins e-books
• Année: 2009
• ISBN:
  9780061800306
• Sujet: Social Sciences
• Sous-sujet: Anthropology

Peter Watson's hugely ambitious and stimulating history of ideas from deep antiquity to the present day—from the invention of writing, mathematics, science, and philosophy to the rise of such concepts as the law, sacrifice, democracy, and the soul—offers an illuminated path to a greater understanding of our world and ourselves.

PART ONE
LUCY TO GILGAMESH

The Evolution of Imagination

1
Ideas Before Language

To Chapter 1 Notes and References

George Schaller, director of the Wildlife Conservation Division of the New York Zoological Society, is known to his fellow biologists as a meticulous observer of wild animals. In a long and distinguished career he has made many systematic studies of lions, tigers, cheetahs, leopards, wild dogs, mountain gorillas and hyenas. His book, The Last Panda, published in 1993, recorded many new and striking facts about the animal the Chinese call the ‘bearcat’. He found that on one occasion a sick panda had gone freely to a human family in the Wolong area, where it was fed sugar and rice porridge for three days, until it recovered and returned to the forest.¹

In the late 1960s Schaller and a colleague spent a few days on the Serengeti plain in Tanzania, East Africa, where they made a simple observation which had escaped everyone else. In the course of those few days, they stumbled across quite a lot of dead meat ‘just lying around’. They found dead buffalo, the butchered remains of lion kills, and they also came across a few incapacitated animals that would have been easy prey for carnivores. Smaller deer (like Thompson’s gazelles) remained uneaten for barely a day but larger animals, such as adult buffalo, ‘persisted as significant food resources’ for about four days.² Schaller concluded from this that early humans could have survived quite easily on the Serengeti simply by scavenging, that there was enough ‘ruin’ in the bush for them to live on without going hunting. Other colleagues subsequently pointed out that even today the Hadza, a hunter-gathering tribe who live in northern Tanzania, sometimes scavenge by creeping up on lions who have made a kill and then creating a loud din. The lions are frightened away.

This outline of man’s earliest lifestyle is conjectural.³ And to dignify the practice as an ‘idea’ is surely an exaggeration: this was instinct at work. But scavenging, unromantic as it sounds, may not be such a bad starting-point. It may even be that the open African savannah was the type of environment which favoured animals who were generalists, as much as specialists, like a hippopotamus, for example, or a giraffe, and it is this which stimulated mankind’s intelligence in the first place. The scavenging hypothesis has, however, found recent support from a study of the marks made on bones excavated at palaeontological sites: animals killed by carnivores do show tool marks but fewer than those butchered by humans. It is important to stress that meat-eating in early humans does not, in and of itself, imply hunting.⁴

There are two candidates for humankind’s first idea, one rather more hypothetical than the other. The more hypothetical relates to bipedalism. For a long time, ever since the publication of The Descent of Man by Charles Darwin in 1871, the matter of bipedalism was felt to be a non-issue. Following Darwin, everyone assumed that man’s early ancestors descended from the trees and began to walk upright because of changes in the climate, which made rainforest scarcer and open savannah more common. (Between 6.5 million and 5 million years ago, the Antarctic ice-cap sucked so much water from the oceans that the Mediterranean was drained dry.) This dating agrees well with the genetic evidence. It is now known that the basic mutation rate in DNA is 0.71 per cent per million years. Working back from the present difference between chimpanzee and human DNA, we arrive at a figure of 6.6 million years ago for the chimpanzee–human divergence.⁵

Several species of bipedal ape have now been discovered in Africa, all the way back to Sahelanthropus, who lived six to seven million years ago in the Djurab desert of Chad and was close to the common ancestor for chimpanzees and humans.⁶ But the human ancestor which illustrates bipedalism best is Australopithecus afarensis, better known as ‘Lucy’, because on the night she was discovered the Beatles’ song ‘Lucy in the Sky with Diamonds’ was playing in the palaeontologists’ camp. Enough of Lucy’s skeleton survives to put beyond doubt the fact that, by 3.4 to 2.9 million years ago, early humans were bipedal.

It is now believed that the first and most important spurt in the brain size of man’s direct ancestors was associated with the evolution of bipedalism. (Most important because it was the largest; there is evidence that our brains are, relative to our bodies, slightly smaller now than in the past.)⁷ In the new, open, savannah-type environment, so it is argued, walking upright freed the arms and hands to transport food to the more widely scattered trees where other group members were living. It was bipedalism which also freed the hands to make stone tools, which helped early man change his diet to a carnivorous one which, in providing much more calorie-rich food, enabled further brain growth. But there was a second important consequence: the upright posture also made possible the descent of the larynx, which lies much lower in the throat of humans than in the apes.⁸ At its new level, the larynx was in a much better position to form vowels and consonants. In addition, bipedalism also changed the pattern of breathing, which improved the quality of sound. Finally, meat, as well as being more nutritious, was easier to chew than tough plant material, and this helped modify the structure of the jaw, encouraging fine muscles to develop which, among other things, enabled subtler movements of the tongue, necessary for the varied range of sounds used in speech. Cutting-tools also supplemented teeth which may therefore have become smaller, helpful in the development of speech. None of this was ‘intended’, of course; it was a ‘spin-off’ as a result of bipedalism and meat-eating. A final consequence of bipedalism was that females could only give birth to relatively small-brained offspring–because mothers needed relatively narrow pelvises to be able to walk efficiently. From this it followed that the infants would be dependent on their mothers for a considerable period, which in turn stimulated the division of labour between males and females, males being required to bring back food for their mates and offspring. Over time this arrangement would have facilitated the development of the nuclear family, making the social structure of the cognitive group more complex. This complex structure, in which people were required to predict the behaviour of others in social situations, is generally regarded as the mechanism by which consciousness evolved. In predicting the behaviour of others, an individual would have acquired a sense of self.

This is all very neat. Too neat, as it turns out. Whereas early humans began walking upright six million years ago, the oldest stone tools are about 2.5 to 2.7 million years old (and maybe even three million years old)–too long a time-lag for the developments to be directly linked. Second, modern experiments have shown that bipedalism does not increase energy efficiency, and as more fossils have been found we now recognise that early bipedal apes lived in environments where trees were plentiful.⁹ In these circumstances, Nina Jablonski and George Chaplin, of the California Academy of Sciences, have suggested that the real reason humans became bipedal was as a way to appear bigger and more threatening in contests with other animals, and in so doing avoid punishing conflicts and gain access to food. The idea behind this is taken from observations of gorilla and chimpanzee behaviour in the wild. Both types of ape stand upright, swagger, wave their arms about and beat their chests when threatening others in contests over food or sexual partners. Such displays are not always effective but they are often enough for Jablonski and Chaplin to suggest that ‘individuals who learned to defuse tense situations with bipedal displays could have reduced their risk of injury or death and thus, by definition, improved their reproductive chances’. On this scenario, then, bipedalism, though a physical change to the body frame of early humans, developed because it had behavioural–psychological–consequences of an evolutionary kind. Almost certainly, however, it too had a large instinctive element, and for that reason can at best be called a proto-idea.¹⁰

The second candidate for man’s earliest idea is much better documented. This is the emergence of stone tools. As we shall see, the manufacture of stone tools went through at least five major phases in pre-history, as early man’s handling of raw stone became more sophisticated. The most important dates to remember, when major changes in technology occurred, are 2.5 million years ago, 1.7 million, 1.4 million, 700,000, and 50,000–40,000 years ago.¹¹ The oldest artefacts yet discovered come from the area of the river Gona in Ethiopia. They consist mainly of selected volcanic pebbles from ancient streambeds and are often difficult to distinguish from naturally-occurring rocks. At some point, about 2.5 million years ago, ancient man learned that if he struck one stone against another in a particular way, a thin, keen-edged flake could be knocked off which was sharp enough to pierce the hide of a dead zebra, say, or a gazelle. To the untutored eye, a primitive stone axe from Gona looks little different from any pebble in the area. Archaeologists have noticed, however, that when a flake is deliberately manufactured by another rock being struck against it, it usually produces a distinctive swelling, known as a ‘bulb of percussion’ immediately next to the point of impact. This is used by professionals to distinguish human artefacts from mere broken stones arising from natural ‘collisions’ as a result, for example, of water action.¹²

Although a cultural artefact, the link between stone tools and man’s later biological development was momentous. This is because, until 2.5 million years ago, early man’s diet was vegetarian. The invention of stone tools, however, enabled him to eat meat–to get at the muscles and internal organs of big and small game–and this had major consequences for the development of the brain. All mammals–primates, and especially humans–are highly encephalised: they have brains that are large when compared with their body mass. Compared with reptiles of the same size, for example, mammals have brains that are, roughly, four times as big.¹³ In modern humans, the brain comprises only 2 per cent of body weight, but it consumes 20 per cent of the body’s metabolic resources. As we shall see, each major change in stone technology appears to have been accompanied by an increase in brain size, though later increases were nowhere near as large as the first spurt.¹⁴

That some major change in brain structure–in size and/or organisation–occurred about 2.5 million years ago is not in doubt. At one stage it was thought that tool-making was a defining characteristic of ‘humanity’ but that was before Jane Goodall in the 1960s observed chimpanzees pulling the leaves off twigs so they could insert the twigs into termite mounds, and then withdraw them–by now suitably coated with termites–to be eaten at leisure. Chimpanzees have also been observed cracking open nuts using stones as ‘hammers’ and, in Uganda, using leafy twigs as fans, to keep insects away. However, palaeontologists recognise two important ways in which early hominid stone tools differ from the tools produced by other primates. The first is that some of the stone tools were produced to manufacture other tools–such as flakes to sharpen a stick. And second, the early hominids needed to be able to ‘see’ that a certain type of tool could be ‘extracted’ from a certain type of rough rock lying around. The archaeologist Nicholas Toth of Indiana University spent many hours trying to teach a very bright bonobo (a form of pygmy chimpanzee), called Kanzi, to make stone tools. Kanzi did manage it, but not in the typical human fashion, by striking one stone against another. Instead, Kanzi would hurl the stones against the concrete floor of his cage. He just didn’t possess the mental equipment to ‘see’ the tool ‘inside’ the stone.¹⁵

Early stone tools similar to those found on the Gona river have also been found at Omo in southern Ethiopia, at Koobi Fora, on lake Turkana just across the border in Kenya and, controversially, in the Riwat area of northern Pakistan. In some circles these tools are referred to as the Omo Industrial Complex. The Omo industry is followed by the second type of stone tool, called Oldowan, after the Olduvai gorge, and dating to between 2.0 and 1.5 million years ago. Olduvai, in Tanzania, near the southern edge of the Serengeti plain, is probably the most famous location in palaeontology, providing many pioneering discoveries.

Stone tools, in general, do not occur in isolation. At several sites in Olduvai, which have been dated to about 1.75 million years ago, the tools were found associated with bones and, in one case, with larger stones which appear to be fashioned into a rough semi-circle. The feeling among some palaeontologists is that these large stones formed a primitive wind-break (man’s second idea?), offering shelter while animals were butchered with the early hand-axes. The stone tools in use 1.7 million years ago were already subtly different from the very earliest kinds. Louis and Mary Leakey, the famous ‘first family’ of palaeontologists, who excavated for many years at Olduvai gorge, carefully studied Oldowan technology and although by later standards the stone tools were very primitive, the Leakeys and their colleagues were able to distinguish four ‘types’–heavy duty choppers, light duty flakes, used pieces and what is known as débitage, the material left over after the tools have been produced. There is still much discussion as to whether the early hominids at Olduvai were passive scavengers, or confrontational scavengers, as the Hadza are today.¹⁶

Who made these early tools? Nothing of the kind has ever been found associated with A. afarensis remains. By the time tools appear, various species of hominid co-existed in Africa, two or three of which are given the family name Paranthropus (‘alongside man’), also known as A. robustus and A. boisei, with the others belonging to Homo–these are H. habilis (‘Handy man’), H. rudolfensis and H. ergaster. These different hominids varied in interesting ways that make the exact line of descent to ourselves difficult to fathom. All had bigger brains than ‘Lucy’ (500–800 cc, as compared with 400–500 cc), but whereas H. habilis had an ape-type body with more human-like face and teeth, H. rudolfensis was the other way round–a human-type body and more ape-like face and teeth.¹⁷ In theory, any of these species could have produced the tools but two reasons seem to rule out Paranthropus. The first reason relates to the thumb of primitive man. The anthropologist Randall Susman has noticed that chimpanzees have very different thumbs from human beings. Chimps have curved, narrow-tipped fingers and short thumbs–ideal for grasping tree limbs. Humans, on the other hand, have shorter, straighter fingers with squat tips, and larger, stouter thumbs. This is a better arrangement for grasping things like stones. On examination, it turns out that A. afarensis had chimpanzee-like thumbs and so, probably, did Paranthropus. A second reason is that, if Paranthropus...