With ‘Bob’ Brain for a day’s excavation at the Swartkrans Cave: he has been working here for nineteen seasons. Standing above the cave shaft, I looked in one direction across a sweep of grassy hills towards the High Veldt, in the other at the glinting roofs of the Sterkfontein site and, beyond, the mountainous spoil-heap of the Krugersdorp Mine.
The surface of the ground was broken by small jagged boulders, which made walking very difficult. There was a scarlet aloe in flower but there were no trees or, rather, no trees on the plain. Yet, inside the cave mouth, a stinkwood reared its spotted trunk, its leaves giving shade to the excavation. Only in protected places can seedlings survive the bushfires and frost.
Brain showed me the breccia which has yielded so many fossils of the muscular, ‘King-Kong-like’ form of Australopithecus, A. robustus: a creature known to have co-existed in this valley with the first man, Homo habilis, more than two million years ago.
The foreman, George, was a seasoned excavator. He would dig out one cubic foot at a time, and pass the contents through a griddle. Brain would take each fragment of bone, and scrutinise it under a glass.
In the heat of the day, we rested inside his hut. On the bookshelf was a copy of Sir Thomas Browne’s Religio Medici. It was here that Brain wrote the greater part of his book, The Hunters or the Hunted? – the most compelling detective story I have ever read.
Brain, the Director of the Transvaal Museum in Pretoria, is a quiet, meditative, self-effacing man of ascetic convictions and limitless patience. His father was an English entomologist who went out to Rhodesia to work in pest control. His mother was Afrikaans. He is the great-great nephew of Eugène Marais, the poet, naturalist and recluse, whose Soul of the White Ant was plagiarised by Maeterlinck.
Brain has defined the true naturalist as ‘a man who is in love with the world’, and believes the only way of approaching nature is to try and see things the way they are ‘without filters’. He is haunted by the fragility of human life, and always looking for ways of preserving it.
He hates being locked into any one discipline and has, at one time or another–with a kind of ‘Taoist’ abnegation – immersed himself in zoology, geology, prehistory and climatology. He has written on the behaviour of monkeys; on geckoes; on chameleons; and on the side-winding adder of the Namib Desert. Once he has finished with Swartkrans, he intends to go back to protozoa – ‘those single-celled bundles of vitality’, to be found in the most brackish desert wells, and which eat, reproduce and die within the space of a few hours.
As a young man, in 1955, Brain attended the Third Panafrican Congress of Prehistory and heard Raymond Dart expounding his views on the Bloodbath. He felt that man, as a species, was being libelled – and he was perhaps the only person present who knew why.
He had, it happened, been working as a soil geologist on the breccias of Makapansgat and doubted that Dart was justified in interpreting every scrap of bone in the cave as a tool or weapon. Besides, although murder and cannibalism did occur, sporadically, throughout the animal kingdom – usually as a response to overcrowding or stress – the idea that murder made man made no evolutionary sense.
For ten years, Brain mulled over Dart’s thesis; and, on becoming Director of the Museum, he decided to take the matter in hand.
In the Sterkfontein valley there are three dolomitic limestone caves where hominid fossils have been found: Sterkfontein itself, Swartkrans and Kromdraai. Once he had satisfied himself that conditions here were essentially the same as at Makapansgat, he set to work.
Each of the caves is filled with a breccia of bone and sediment which has squashed down in layers over a period of two to three million years. The bones vary in size from those of an elephant to those of a mouse. Among them are several species of extinct baboon and two forms of Australopithecus: at Sterkfontein, the earlier, ‘gracile’ A. africanus; at Swartkrans and Kromdraai, its descendant, the muscular A. robustus.
There are also the bones, not many, of man.
Some of these hominid bones do show unmistakable signs of a violent end. If it could be shown that other hominids had brought them into the cave, they would have to face the charges of murder and cannibalism. If not, not.
Brain subjected about 20,000 bones to a meticulous ‘forensic’ examination: to decide how each one found its way into the cave and how it came to be in its present condition. Some bones were perhaps washed in by floodwaters. Some were brought there by porcupines, which are known to hoard bones and sharpen their teeth on them. The smaller rodents will have arrived in owl pellets. The bones of the larger mammals – elephant, hippo, lion – will probably have been the work of scavenging hyenas.
But none of this alters the general picture: that all three caves were the lairs of carnivores, and that the overwhelming majority of bones had belonged to animals which had been killed outside the cave, and dragged ‘home’ to be eaten in the darkness. The fossils represented the discarded food remains.
It is unnecessary to go over the ingenuity of Brain’s method: except to point out that all those antelope bones which Dart claimed were bludgeons and daggers and so forth were precisely those parts of the skeleton which a big cat would leave after its meal.
As for the scarcity of hominid fossils – other than the skull and jawbones – Brain observed how, while eating a baboon, a cheetah will crunch up most of the skeleton, except the extremities and the skull. The slight ‘mutilation’ sometimes found at the base of the skull was explained by the animal’s habit of breaking the braincase at its weakest point (the foramen magnum) and then licking out the contents.
A primate skeleton is that much more fragile and digestible than that of an antelope.
All big cats kill with a neck bite – in common with the executioner’s axe, the guillotine and the garrotte. In his Reflections on the Guillotine, Camus records how his father, a solid petit bourgeois of Oran, was so outraged by a gruesome murder that he went to the man’s public guillotining–and came away vomiting helplessly.
The sensation of being mauled by a big cat may, as we know from Dr Livingstone’s experience with a lion, be slightly less horrific than one imagined, ‘It causes’, he wrote, ‘a kind of dreaminess, in which there was no sense of pain nor feeling of terror. It was like what patients under chloroform describe who see all the operation but feel not the knife . . . This peculiar state is probably produced in all animals killed by the carnivores; and, if so, is a merciful provision by our benevolent creator for lessening the pain of death.’
Missionary Travels
Transvaal Museum, Pretoria
An afternoon with Dr Elizabeth Vrba, a palaeontologist, Brain’s chief assistant–and a spellbinding talker! We sat on the floor of the so-called Red Room and handled, with white gloves, such famous fossils as ‘Mrs Ples’: an almost complete skull of A. africanus found by the late Robert Broom in the 1930s.
To have in one hand the delicate jawbone of africanus and in the other the huge grinding molars of robustus was like handling the horseshoe of a Shetland pony and that of a Shire horse.
The Sterkfontein Valley fossils are all late compared to those of Kenya and Ethiopia, where the archaic, midget form of Australopithecus, A. afarensis (the type specimen is ‘Lucy’), is now believed to have been walking upright around six million years ago. The earliest ‘South Africans’ are, on present showing, about half that age.
Elizabeth Vrba showed me how the three forms of Australopithecus represent three stages in an evolutionary chain, becoming bigger and more muscular in answer to progressively drier and more open conditions.
At what point the first man splits off from this line is a question the experts are going to argue ad infinitum. Every fieldworker wants to find HIM. But, as Brain warned, ‘To find a beautiful fossil, and then hitch your reputation to it, is no longer to see the fossil.’
The fact is that, at a date some time after 2.5 million, there appears in eastern Africa a small, agile creature with a very startling development to his frontal
lobes. In all three stages of Australopithecus, the proportion of body to brain stays constant. In man, there is a sudden explosion.
Elizabeth Vrba has written a series of internationally acclaimed papers on the rates of evolutionary change. It was she who sharpened my awareness of the debate between the ‘gradualists’ and the ‘jumpers’.
Orthodox Darwinians believe that evolution proceeds in a stately continuum. Each generation will differ imperceptibly from its parents; and when the differences are compounded, the species crosses a genetic ‘watershed’ and a new creature, worthy of a new Linnaean name, comes into being.
The ‘jumpers’, on the other hand – in keeping with the brutal transitions of the twentieth century – insist that each species is an entity with an abrupt origin and an abrupt end; and that evolution proceeds in short bursts of turmoil followed by long periods of idleness.
Most evolutionists believe that climate is a motor of evolutionary change.
Species, on the whole, are conservative and resistant to change. They will go on and on, like partners in a shaky marriage, making minor adjustments here and there, until they reach a bursting point beyond which they cannot cope.
In a climatic catastrophe, with its habitat fragmenting all around, a small breeding community may get hived off from its fellows and stranded in an isolated pocket, usually at the far end of its ancestral range, where it must transform itself or die out.
The ‘jump’ from one species to the next, when it does come, comes quickly and cleanly. Suddenly, the new arrivals no longer reply to old mating calls. In fact, once these ‘isolating mechanisms’ take hold, there can be no genetic backsliding, no loss of new features, no going back.
Sometimes the new species, invigorated by the change, may re-colonise its former haunts, and replace its predecessors.
The process of ‘jumping’ in isolation has been called ‘allopatric speciation’ (‘in another country’) and will explain why, whereas biologists find countless variations within a species – in body size or pigmentation – no one has ever found an intermediate form between one species and the next.
The search for the origin of man may thus turn out to be a hunt for a chimera.
The necessary isolation required for ‘jumping’ can, it seems, equally well exist along a migration path or track – which is, after all, an area of territory spun out into a continuous line, as one would spin a fleece into yarn.
Reflecting on the above, I was struck by the similarity between ‘allopatry’ and the Aboriginal myths of creation: in which each totemic species is born, in isolation, at one particular point on the map, and then spreads out in lines across the country.
All species must ‘jump’ eventually, but some jump more readily than others. Elizabeth Vrba showed me graphs on which she had plotted the lineage of two sister clades of antelopes, the Alcephalini and Aepycerotini, both of which shared a common ancestor in the Miocene.
The Alcephalini, the family to which the wildebeeste and hartebeeste belong, have ‘specialised’ teeth and stomachs for feeding in arid conditions, and have thrown up about forty species over the past six and a half million years. The impala, a member of the Aepycerotini, being a generalist with a capacity to thrive in a variety of climates has remained the same to this day.
Evolutionary change, she said, was once hailed as the hallmark of success. We now know better: the successful are the ones that last.
The really important news is that we belong to a most stable lineage.
The ancestors of man were ‘generalists’: resilient and resourceful creatures who, over the same period as the impala, will have had to wriggle out of many a tight corner without having to speciate at every turn. It follows that when you do find a major architectural change in the hominid line, there must be some ferocious external pressure to account for it. Also, that we may have a far more rigid moral, instinctive backbone than we hitherto suspected.
Since the close of the Miocene, there have, in fact, been only two such major ‘leaps forward’, separated one from the other by an interval of roughly four million years: the first associated with Australopithecus, the second with man:
The restructuring of the pelvis and foot from those of a brachiating forest ape to those of a walker on the plain; from a four-limb to a two-limb plan; from a creature that moved with its hands to one whose hands were free for other things.
The rapid expansion of the brain.
Both ‘leaps’, it turns out, coincide with sudden shifts towards a colder and drier climate.
Around ten million years ago, our hypothetical ancestor, the Miocene ape, will have spent his days in the high-canopy rain forest which covered most of Africa at the time.
Like the chimpanzee and gorilla, he will probably have spent each night in a different spot, yet confined his wanderings to a few unadventurous square miles of territory, where food was always available, where the rain fell in runnels down the tree-trunks and sunlight then spattered the leaves; and where he could swing to safety from the ‘horrors’ on the forest floor.
(From Lake Térnéfine in Chad I have seen the fossil skull of a Miocene hyenid: an animal the size of a bull with jaws to slice off the leg of an elephant.)
At the close of the Miocene, however, the trees began to dwindle in size. For reasons as yet unclear, the Mediterranean seems to have absorbed about 6 per cent of the world’s oceanic salt. Because of the decrease in salinity, the seas around Antarctica began to ice up. The size of the ice cap doubled. The sea level fell; and the Mediterranean, cut off by a land-bridge at Gibraltar, became one vast evaporating salt-pan.
In Africa, the rain forest shrank to small pockets – where the arboreal apes are at present to be found – while over the eastern side of the continent, the vegetation became a ‘mosaic savannah’: of open woodland and grass country, with alternating seasons of wet and dry, plenty and want, floodwater and lakes of cracked mud. This was the ‘home’ of Australopithecus.
He was an animal that walked and probably carried loads: upright walking, with its development of the deltoid muscle, seems to presuppose the bearing of weights, probably food and children, from one place to another. Yet his broad shoulders, long arms, and marginally prehensile toes suggest that, in his ‘archaic’ form at least, he still lived partly or took refuge in the trees.
In the 1830s Wilhelm von Humboldt, the father of modern linguistics, suggested that man walked upright because of discourse which would not then ‘be muffled or made dumb by the ground’.
Yet four million years of upright walking had no effect whatever on the development of speech.
All the same, the ‘graciles’ and the ‘robusts’ had, it seems, the ability to fashion simple tools, of bone and even stone. The wear on these tools, when examined under a microscope, suggests they were used, not for butchery, but for rooting up bulbs and tubers. Australopithecus may have snaffled a young gazelle if one came within his grasp. He may even have hunted, systematically, like a chimpanzee. But he was still more or less vegetarian.
As for the first man, he was an omnivore. His teeth are those of an omnivore. From the stone tools strewn around his campsites, he seems to have dismembered carcasses and eaten them. He was, however, probably more scavenger than hunter. His appearance coincides with the second climatic upheaval.
Climatologists have learnt that, between 3.2 and 2.6 million years ago, there occurred a sharp plunge in world temperature known as the First Northern Glaciation, in that the North Polar Ice Cap for the first time froze. In Africa, the results were catastrophic.
Up and down the Great Rift Valley, the woodlands were swept away and replaced by open steppe: a wilderness of sand and gravel, patchy grass and thorn bushes, with taller trees lingering in the watercourse.
Thornscrub was the country into which the brain of the first man expanded: the Crown of Thorns was not an accidental crown.
‘Man’, said Elizabeth Vrba, ‘was born in adversity. Adversity, in this case, is aridity.’
&nb
sp; ‘You mean that man was born in the desert?’
‘Yes,’ she said. ‘The desert. Or at least the semi-desert.’
‘Where the sources of water were always undependable?’
‘Yes.’
‘But there were plenty of beasts about?’
‘A carnivore doesn’t care where he lives so long as he gets his meat. It must have been terrible!’
The evolutionary record is full of ‘arms races’ between predator and prey, since Natural Selection will favour prey with the best defences and predators with the best killing equipment.
A tortoise retires into its shell. A hedgehog raises its spines. A moth will camouflage itself against the bark of a tree, and a rabbit will bolt down a burrow too small for the fox to follow; but man was defenceless on a treeless plain. The response of robustus was to put on more muscle. We used our brains.
It was nonsense, Dr Vrba continued, to study the emergence of man in a vacuum, without pondering the fate of other species over the same time-scale. The fact was that around 2.5 million, just as man took his spectacular ‘jump’, there was a ‘tremendous churning over of species’.
‘All hell’, she said, ‘broke loose among the antelopes.’
Everywhere in eastern Africa, the more sedentary browsers gave way to ‘brainier’ migratory grazers. The basis for a sedentary existence was simply no longer there.
‘And sedentary species,’ she said, ‘like sedentary genes, are terribly successful for a while, but in the end they are self-destructive.’
In arid country, resources are never stable from one year to the next. A stray thunderstorm may make a temporary oasis of green, while only a few miles off the land remains parched and bare. To survive in drought, therefore, any species must adopt one of two stratagems: to allow for the worst and dig in; to open itself to the world and move.
Some desert seeds lie dormant for decades. Some desert rodents only stir from their burrows at night. The weltwitchia, a spectacular, strap-leaved plant of the Namib Desert, lives for thousands of years on its daily diet of morning mist. But migratory animals must move – or be ready to move.