The Seven Daughters of Eve (11 page)

Well supplied with food and water, the canoes set off against the prevailing wind. This might seem like hard work, but it did at least ensure a relatively safe return journey, sailing back downwind to the home port, navigating by the stars. It is fairly straightforward to travel along a line of latitude by keeping a rising or setting star in the same position relative to the canoe each night. When it is time to return home, it is a simple matter of reversing direction and sailing downwind guided by the same stars – simple in theory, but in practice still fraught with danger. It must have been all too easy to miss the home island, especially if it was passed in the night or in a storm. There must have been many losses.

More remarkable still are the signs the Polynesians used to detect the presence of unseen land. Cloud formations above high islands betray their presence over the horizon. The opalescent blue-green of low-lying atolls is reflected in the clouds under the right conditions. The outward and homeward flight directions of birds known to nest on land give clues. Floating debris shows there is land upwind. These are the visible signs. But the early voyagers not only saw their way ahead; they felt it too. Even now traditional navigators can detect the change in the way the sea moves. The underlying swell sweeps across the ocean, but is reflected back from the islands – just as ripples from a stone tossed into a pond bounce back from the edge. Even a hundred miles from land an experienced navigator will use his feet to feel for the interference pattern as one swell crosses another.

That is
how
the Polynesians arrived. It is not
why
. What drove them to these quite extraordinary feats of exploration is still a mystery. It cannot be that they needed to keep moving on to satisfy the economic needs of a growing population. Many of the islands en route to the remote Pacific are large and fertile, and are not densely populated even today. Perhaps it was an insatiable urge to explore the unknown. They must certainly have voyaged right across the Pacific to reach South America. We know this from the evidence of the
kumara
, the sweet potato, which was and is cultivated all over Polynesia. There is no dispute that the sweet potato is a true Andean crop, so this has to mean there must have been at least some contact between the native South Americans and the Polynesians. The genetics rules out Thor Heyerdahl's explanation that the sweet potato was brought into the Pacific by the people who he thought had colonized Polynesia from South America: we had proved beyond any doubt that the colonization of the Pacific had happened in the opposite direction. For the sweet potato to have been imported from South America, the Polynesians must have found their way right across the Pacific. But they left no visible genetic trace in South America. To my knowledge, not a single sample of Polynesian mitochondrial DNA has ever been found there. However, I did eventually find two mitochondrial sequences from Tahiti in French Polynesia that matched published sequences from Chile. I like to think these may have been the faint echo of women who had joined the Polynesians on their return journey back into the Pacific from South America, but I cannot prove it.

The Polynesians discovered and settled Aotearoa, the ‘land of the long white cloud', which we know as New Zealand. The genetics proves that, too, beyond any doubt: the Maori of Aotearoa share exactly the same mitochondrial DNA as their cousins in Polynesia. This agrees perfectly with Maori oral tradition, which relates that a fleet of eight to ten voyaging canoes set out from central Polynesia, perhaps even from Rarotonga itself, and eventually reached Aotearoa. They found a strange but fertile land with no human inhabitants but full of creatures they had never before encountered, including the huge flightless moa, related to the ostrich (and eventually hunted to extinction).

Travelling so far to the south, the voyagers would have left themselves little hope of return had they not discovered land. Getting to Aotearoa was not a simple matter of sailing into the wind along a line of latitude in the knowledge that if no land was encountered it was only necessary to reverse direction and travel home along the same line with the wind behind them. The voyage to Aotearoa took them across latitudes and far to the south of the reliable trade winds into a part of the ocean where the winds were far less predictable. This was another level of maritime exploration altogether, of such maturity and daring that I feel sure the Polynesians must also have reached the coast of Australia, so accomplished were they in the ways of the ocean. But if they did land here, they left no trace. Perhaps they only felt comfortable settling uninhabited lands. Did they, I wonder, sail south of Australia and right across the Indian Ocean to Madagascar – unpopulated then, and now at least partially inhabited by people speaking a similar language? Could they have done that? I'm quite sure they could. Did they? One day, the genes will tell us.

I still feel a sense of excitement when I think about the work in Polynesia. I had found myself on an island in the middle of the Pacific staring out at the ocean beyond the reef and overcome by a burning desire to find the answer to a question. I really wanted to know where the Polynesians had come from. It was a quest born out of pure curiosity; and it had delivered the answer, clear-cut and unequivocal, in a little over three years. Having seen how decisively mitochondrial DNA had settled the matter of Polynesian origins, I was very confident of its inherent ability to solve even harder questions in an arena much nearer home.

The ten-year excavation at Boxgrove near the cathedral city of Chichester in Sussex, England had been productive but not spectacular. Boxgrove is a quarry now; but half a million years ago it was a narrow coastal plain between chalk cliffs and the open sea. The sand and gravel that are now quarried were washed in there by later floods created by the catastrophic melting of later Ice Ages. Over several years Boxgrove had yielded up flint tools and animal bones with cut marks that showed that the carcasses had been deliberately butchered using the razor-sharp stones. If you doubt how sharp these could be, then try knocking a flake from a large piece of flint. It is quite sufficient for a close dry shave. The shaped stones and the bones were obvious signs of human occupation – but there had been no sign of the humans themselves. English Heritage, the government agency that had been paying for the excavation, had already made it clear that it would not fund any more fieldwork. At the beginning of November 1993, with only weeks to go before the excavations were finally abandoned, the archaeologists in charge marked out one last trench and Roger Pedersen started digging.

Roger, one of the army of devoted volunteers that are the lifeblood of all archaeological digs, proceeded to make a start on the trench with his trowel. After two weeks he had dug down into the layers of sand, recording the orientation of every artefact he came across. It was slow and painstaking work, not made any easier by the cold, wind and rain. Then, just after lunch on Friday, 13 November 1993, he found a bone – the shin-bone of a very early human. He had uncovered a fragment of Boxgrove Man. And he had saved the dig.

I was shown the bone soon afterwards, and though I am no expert, even I could see how very thick the walls surrounding the central marrow space were, compared to a modern bone. This was the shin-bone of a massive, heavily built human. But was it the bone of an ancestor? This straightforward question goes to the very heart of the controversy over human origins, for one simple reason: whereas every living human (or animal or bird, for that matter) has ancestors, it does not automatically follow that every human fossil had descendants. Boxgrove Man might be an ancestor of twenty-first-century modern humans, or he might belong to a species that is now extinct.

Exactly the same argument surrounds every human fossil. There are many sites of great antiquity in Europe, in Asia and especially in Africa that have yielded what we would have little trouble recognizing as signs of human activity. These are mainly the remnants of shaped stone tools, which obviously survive extremely well. Occasionally, as at Boxgrove, there are animal bones with deliberate cut marks. And very occasionally, there are actual human bones. These fantastically rare and celebrated specimens have been studied and argued over by palaeontologists for decades. Their names –
Homo habilis
,
Homo erectus
,
Homo heidelbergensis
,
Homo neanderthalensis
– reflect the to and fro of attempts to pigeon-hole them into different species. However, these are species defined on the basis of the anatomical features preserved in the skeletons, particularly the skulls, and not in the biological sense of different, genetically isolated, species who are incapable of breeding with any other. It is an operational classification with no evolutionary consequences. From the shapes of the bones alone there is simply no way of knowing whether humans (I use the term ‘human' to include everything in the genus
Homo
) from different parts of the world were capable of successful interbreeding. If they could interbreed, then this opens up the possibility of their exchanging genes and spreading mutations around. They would all be in the same gene pool. But once the different types of human become incapable of interbreeding, they can no longer exchange genes. They become different
biological
species with isolated gene pools. Their evolutionary pathways are irreversibly separated, setting off in different directions with no turning back. If two or more of these species later come into conflict for space or resources, then, unless a compromise is reached, one species will become extinct.

It is this question that lies behind one of the longest-running and most deep-seated controversies in human evolution. Are the different species defined by palaeontologists –
Homo erectus
,
Homo neanderthalensis
and ourselves,
Homo sapiens
– all part of the same gene pool or not? Or, to put it another way, are modern humans directly descended from the fossils found in their part of the world, or are many of these the remains of now extinct genetically separate human species?

There is no serious doubt that all humans alive today are members of the same species,
Homo sapiens
. Historical events over the last few hundred years have intermingled people from very different parts of the world, producing abundant evidence of successful interbreeding between all possible combinations. At least, I say that without being completely sure that the opportunity has arisen for absolutely
all
possible combinations to have been tried; but I'm certain that there would be no genetic barrier to success if they were.

The human fossil record, incomplete and patchy though it is, consistently points to Africa as the ultimate origin of all humans. In Africa and only in Africa is there a sensible progression of fossils covering the past three million years and showing intermediate forms from ape to man. Judging by the fossil record, early humans spent at least another million years in Africa before beginning to venture further afield. Remains in Java and China resemble much older
Homo erectus
fossils from Africa not only in their general overall physical appearance but also in the types of stone tools found at the sites.
Homo erectus
was certainly convincingly human, fully upright with a large brain and capable of making and using sophisticated stone tools. But there are no signs of any more primitive, intermediate fossils anywhere outside of Africa. However, while the fossil record is unambiguous in identifying Africa as the cradle of humanity – a conclusion with which very few would nowadays disagree – we should bear in mind some of its limitations. No human fossils have ever been found in west Africa, for example. That does not mean humans were not there until recently; only that the tropical rainforests are not good places to turn into a fossil when you die. No fossils of any of the great apes – gorillas, chimpanzees or orang-utans – have ever been found. As far as the fossil record is concerned, they never existed; and yet we know from the evidence of our own eyes that they did, and do.

Though the fragments of Boxgrove Man and a handful of others are the only glimpses we have of the very earliest European humans, who lived over half a million years ago, the more recent history of Europe is inextricably linked to one dominant form – the Neanderthals. In 1856, workmen quarrying limestone in the Neander valley near Düsseldorf in Germany had just blasted out a small cave and were cleaning away the debris when they came across part of a skull, then thigh-bones, ribs, arm-and shoulder-bones. They thought at first they had come across the remains of an extinct cave bear, an almost routine find in that part of Europe. Only by chance did they happen to mention their discovery to a local schoolteacher and enthusiastic naturalist, Johann Karl Fuhlrott, who realized as soon as he saw the remains that this was no cave bear. Exactly what it was remained controversial for several years. The skull was not that of an ape; but then, with its massive brow ridges, it wasn't exactly human either. For a start, how old was it?

The Neander valley – in German, Neanderthal – bones were found at a time when the biblical account of the creation was coming under attack from geologists who could not accept that the world was only a few thousand years old. Three years later Charles Darwin published
On the Origin of Species
and the status of the Genesis story as literal truth started to crumble. Gradually the idea that humans had really ancient predecessors became more widely accepted; and it looked increasingly as though the Neanderthal ‘man' might be one of them. But this conclusion was reached only after discounting the usual crop of red herrings that accompanies unexpected finds like this. They ranged from the sublime – this was the skull of a man with a mystery bone disease which caused the thickening and the brow ridges – to the ridiculous – it was the skeleton of a Cossack horseman who had been injured in the Napoleonic Wars and crawled into the cave to die. Without his sword and uniform…?

Over the next hundred years, several other fossils were found that conformed to the same pattern: heavy build; large braincase (actually slightly larger than the modern average), presumably to accommodate a large brain; no real chin; a prominent nose; and those distinct, heavy brow ridges. The fossils came from Gibraltar and southern Spain – in fact, the first Gibraltar specimen had been excavated in 1848, eight years before the discovery at Neanderthal, but was neglected. They were found in Belgium, France, Croatia; and from further afield in Israel, Iraq and as far east as Uzbekistan. The stone tools found at Neanderthal sites were more advanced than those associated with their predecessors, though not a great deal. They may have intentionally buried their dead and even cared for the sick and dying. These were not the unreconstructed brutes of popular imagination. But still the question remained: were these people the ancestors of modern Europeans or just another evolutionary dead end?

The same question applies to other parts of the world. Are modern Chinese the descendants of the people whose million-year-old remains were found at Zhoukoudian near Beijing? Did the ancient people of Ngandong in Java eventually become the modern native Australians and Papuans? That is certainly the view of an influential and vocal school of contemporary physical anthropologists – the multi-regionalists. They see the change in human physical characteristics over the past million years from the robust, heavy-boned ancestors to their slender (at least theoretically!) and light-boned descendants as a gradual process of adaptation happening at different speeds in different parts of the world. Though geographically remote from each other, there has been enough contact among these groups to maintain a common gene pool and allow modern
Homo sapiens
to breed successfully with whomever he or she wishes. Always assuming they get the chance.

The opposite camp – the replacement school – fiercely contests this view of continuity. Their view is that both the Neanderthal and the Zhoukoudian and Ngandong fossils, also known as Peking and Java man, are remnants of extinct human species that were replaced by a much more recent expansion of
Homo sapiens
out of Africa. The fossil evidence put forward in support of this contention is the abrupt appearance in Europe about forty-five thousand years ago of humans with much lighter skeletons and skulls which are virtually indistinguishable from those of modern Europeans. There is no debate, even among the most argumentative of palaeontologists, that these are the remains of our own species,
Homo sapiens
. In Europe, these early examples are known as the Cro-Magnons, named (in the same tradition as the Neanderthals) after the cave site of Cro-Magnon in France: one of the places where, in 1868, such bones were first found. It is inconceivable, according to the replacement school, that a mutation of such magnitude could have occurred as to transform the heavily built Neanderthals into the thoroughly modern-looking Cro-Magnon more or less (in evolutionary time) overnight. The archaeological as opposed to the fossil evidence for an abrupt replacement of Neanderthals by Cro-Magnons is the use of a much more highly developed and delicately crafted set of tools, with flint slivers used for knives, scrapers and engravers; the appearance for the very first time of animal bone and antler as an industrial material; and one more crucial ingredient – art.

The Cro-Magnons had invented representational art. Over two hundred caves in France and northern Spain are adorned with their strangely beautiful and vigorous images of wild animals. Deer and horses, mammoths and bison decorate the walls of the deepest caverns, far from the light of day. These are not crude or child-like drawings but the expression of a mature and accomplished imagery, an abstracted and mystical representation of their world.

Is it possible that the Neanderthals had not only transformed their physical appearance and their technology, but had also become artists as well? The multi-regionalists think just that, and, indeed, see in some remains and stone tools evidence of the intermediate forms you would expect from a gradual transition. But there are no precedents for the cave art anywhere in the lands where Neanderthals have been found. The school of sudden replacement traces the modern anatomy and the improved technology back to Africa, to sites like Omo-Kibish in Ethiopia, which are well over a hundred thousand years old. Even so, although anatomically modern skulls have been found along the trail to Europe in the Near East, principally at Qafzeh and Skhul in Israel, there was no sign there of art.

Without new evidence from a completely different and independent source, genetics, the debate about whether native Europeans were descended from Neanderthals or from the apparently distinct later arrivals, the Cro-Magnons, would have rumbled on unresolved. In all fields of human endeavour where there is a shortage of objective evidence, opinions and people inevitably become polarized into rival camps. Once entrenched, the occupants will not be dislodged; they would rather die than change their minds. Such was the situation when we set out to apply our powerful genetic tools to the conundrum; so we knew the path ahead would likely lead us into a minefield.