The Incredible Human Journey

by Alice Roberts

  We took our length of bamboo down to the village, where this material was still being used to make all manner of things. There were piles of long, thick bamboo trunks lying around, ready for construction. We were invited into a house in which there were piles of bamboo baskets stacked up, and an old man was in the process of weaving one out of long, bendy strips of bamboo epithelium, or ‘bark’. In the yard, small ducklings had nestled together under a bamboo cage.

  Jo and I set to work on our bamboo tools. Using very basic, unretouched stone flakes, we pared down slivers of bamboo and quickly made sharp-edged ‘knives’. I was surprised at how quick and easy the process was, though sceptical about just how sharp and strong my bamboo knife would prove to be. The family had a chicken carcass ready for supper, and, using my brand new bamboo knife, I made short work of butchering it, separating drumsticks, wings and breasts from the carcass (I may be a vegetarian but I’m also an anatomist). The use of bamboo knives has been documented right across the Pacific. Ethnographic studies have also shown that bamboo may even be used in preference to stone tools: the stone-adze-makers of Irian Jaya in New Guinea, for example, like to use a simple piece of split bamboo for butchering.5 And although my green bamboo knife had done the job well, Jo said it would have been even sharper had it been dried bamboo.

  It was clear that bamboo could be used to make excellent cutting tools as well as being suitable for houses, baskets – and even, as I had already seen, rafts. It was a wonderfully versatile material. (You could eat it, too. Bamboo became one of my favourite dishes on my visit to China, not as the more familiar, delicate white bamboo shoots, but as inch-long pieces of thick shoots, rather like asparagus but crunchier – and delicious.) However, the fact that bamboo could be used to make efficient tools isn’t proof that it was used. Neither is the fact that bamboo is still being used in some places to make tools.

  So was there any archaeological evidence of bamboo tools?

  ‘Well, no, not of the bamboo itself,’ admitted Jo. ‘But there is evidence of bamboo being worked – as well as other materials like rattan and palm wood – because there’s a high silica content in these materials. Using a stone tool on bamboo leaves a very distinctive polish on that tool.’

  This polish could be seen with the naked eye; Jo had brought along with him some stone flakes that he had used to cut bamboo, and I could see the polishing quite clearly, next to the cutting edge.

  ‘How long does it take for this type of polish to develop?’ I asked him.

  ‘It starts to form immediately,’ he replied. ‘You can see the polish appearing within the first few minutes of cutting bamboo or rattan.’

  Employing microscopic use-wear analysis, it was actually possible to find out exactly what had been cut: different materials leave different tell-tale marks on stone tools.6 Under a light or electron microscope, minute abrasions and polishing on tool edges provide clues that allow the material that was cut to be identified. This means that archaeologists should be able to tell if stone tools have been used to cut into bamboo, or rattan, or other materials. It may also be possible to find evidence of bamboo tool use as well. A study of experimentally produced cut marks on bone showed that it was possible to tell the difference between cuts made with bamboo knives or stone flakes, using scanning electron microscopy, which produces a very detailed, 3D image.3

  Jo had found examples of polish from cutting rattan on archaeological stone tools from a rockshelter in Timor. But those tools had been only a few thousand years old.

  ‘What I’d really like to do is look at the very early, Chinese stone tools,’ said Jo.

  As more Asian Palaeolithic sites are discovered, it is clear that the toolkits are more variable than was apparent to Movius in the 1940s, when he drew a simple distinction between Acheulean hand axes in the West and chopper-chopping tools in the East. His scheme also lifted the tools out of their environmental context: it didn’t take into account what the tools may have been used for, or the raw materials that were available to the toolmakers. Archaeologists now caution against ranking various toolkits in terms of how sophisticated the tools may appear, and also argue that Palaeolithic toolkits are generally more diverse than previously thought, reflecting intelligent adaptations to a variety of environments.5

  However, even with new discoveries and the emerging impression of a wider variety of stone tools in East Asia, there is still a clear distinction between the tools of East and West. Bamboo technology provides a tempting explanation for that difference. Bamboo was everywhere, whereas it may have been difficult to find sources of good quality, workable stone in the rainforest. Modern rainforest-based hunter-gatherers are mostly vegetarian and occasionally eat small animals – which would have been easily butchered with bamboo knives, just as I had managed to prepare the chicken in the village. Heavy-duty butchery tools would have been redundant in the rainforest.3 I had seen how quick and easy it was to make a good, sharp bamboo knife, using just a simple stone flake. Bamboo technology seemed as if it would have been a sensible, expedient adaptation to rainforest environments.

  Although bamboo itself may be missing from the archaeological record, microscopic use-wear analysis of stone tools and examination of cut marks on bones now provides archaeologists with an opportunity to test this theory. It may not be long before we know for sure whether bamboo use really can explain the simplicity of stone tools in East Asia.

  However, we are still left with a problem: there is no clear difference between the archaeology associated with archaic humans and early modern humans in East Asia. Surely we should find some kind of ‘signal of modernity’ as soon as modern humans arrive on the scene? Shouldn’t modern humans carry with them some badge of superior intelligence, a mark of technological sophistication that has been lacking from previous human incarnations?

  But are we once again falling into the trap of divorcing stone tools from their environmental context? We should not even start to think about a tool assemblage without first firmly placing our toolmakers in their environment. The suggested bamboo explanation for the basic stone tools of East Asia could work for archaic human populations just as it does for modern ones: an intelligent solution to tool-making in a rainforest environment, where bamboo abounds.

  So why do the tools change at around 30,000 years? If it’s not a different toolmaker, what is it? What is changing at that time? The answer is: climate. And at 30,000 years ago, East Asia was starting to feel the cold and dryness of the approaching LGM. And now we really do see the signature of modern human behaviour: when the environment changed around them, the modern humans in East Asia adapted, by inventing new technologies.

  East Asian Genes to the Rescue: Shanghai, China

  I wanted to find out just what Chinese genes revealed about regional continuity versus a recent African origin. And I wanted to speak to a Chinese geneticist.

  It was time to leave Beijing and move on to China’s commercial capital, Shanghai. Beijing had seemed grey and somehow very stolid. It felt like a place where dogma would have very deep foundations. On first impressions alone, Shanghai felt more progressive, cosmopolitan and open. The centre of the city was an architectural palimpsest, with pre-war art deco hotels standing next to concrete high-rises, with ugly flyovers and an elegant museum shaped like an ancient bronze cauldron. On the main streets, international brands jostled for room alongside homegrown shops, and gigantic screens mounted high on buildings displayed streams of advertisements. There was even a huge screen being carried up and down the Huangpu River on a boat. From the Bund, I watched the Pudong district lighting up at dusk, as though it was, itself, a huge advertisement for commercialism and capitalism. China was changing.

  I drove out to Fudan University, to the Institute of Genetics, to meet Professor Jin Li. He showed me around labs where teams of enthusiastic post-doctoral researchers were busy with pipettes and centrifuges. It was out of these labs, some seven years earlier, that compelling genetic evidence about the origin of the Chinese p
eople had emerged.

  Li’s research group had undertaken a massive project designed to test the competing hypotheses about the origins of East Asians.

  ‘I wanted to see if I could find evidence for regional continuity in the genes of Chinese,’ he explained. ‘I decided to look at the Y chromosome, and I started off using a marker of recent African origin, which would allow me to filter out those individuals and leave me with other lineages that may have survived locally through regional continuity. We took thousands of DNA samples from people all over China.’

  So Li had started off wanting to prove the patriotic theory that the modern Chinese had a heritage in China which stretched back, unbroken, to Homo erectus, a million years ago. The genetic marker he had used was a mutation at a site on the Y chromosome called M168, a swap of a cytosine base to thymine, which previous studies had suggested was present in all non-African populations. But previous studies had taken only limited samples from Asia. Li’s group had collected DNA samples from more than 12,000 men from South-East Asia, Oceania, East Asia, Siberia and Central Asia, with the idea that, somewhere among them, there would be much more ancient, non-African Y chromosomes.1

  ‘We knew that the old type of M168 mutated to the new type about 80,000 years ago, in Africa. So if the Out of Africa hypothesis was true, we would expect that everybody in China would be carrying the new type of M186. But if there had been an independent origin of modern humans in China, we should be able to see that at least some people were carrying the old type.’

  ‘And what did you find?’

  ‘We did not see any old type in the Chinese population. In fact, we had a very large sample covering almost every corner of East Asia, and everybody was carrying the new type of M168.’

  The ubiquity of the M168 mutation in Chinese DNA showed that modern humans emerging from Africa had completely replaced earlier East Asian populations.1 Peking Man had no descendants alive today.

  ‘And what did that result mean to you?’ I asked.

  ‘Well, as a Chinese, of course I wanted to find evidence that we have ancient roots in China. That was my education,’ said Jin. ‘It is what we are all taught. But, as a scientist, I have to accept the evidence. And the evidence showed that the recent Out of Africa hypothesis is right. Regional continuity can’t be true.’

  ‘Do you think, on balance, that other genetic evidence supports Out of Africa?’ I asked him.

  He was categorical in his reply: ‘I would make a stronger statement: it exclusively supports the Out of Africa hypothesis.’

  Genetics also offered some insight into how the East had become colonised by modern humans. A greater diversity of Y chromosomes in the south, including among Thais and Cambodians, tells the tale of initial colonisation of South-East Asia, followed by a northwards migration. And the Y chromosome tree suggests a very broad range for the initial date of entry into East Asia, at some time between 25,000 and 60,000 years ago.2 Mitochondrial DNA analyses also show greater diversity in the south, and support the main theme of a south-to-north colonisation of the Far East. The four main haplogroups in East Asia (B, M7, F and R) are all about 50,000 years old.3

  It is quite extraordinary that, despite the thousands of years since the initial colonisation of the East, and all the population movements that have occurred since then, it is still possible to look into the genes of living East Asians and find the clues to where they first came from. Like a piece of parchment that has been written over and over, the faint traces of the original story are still there. Analysis of complete mtDNA sequences shows a distinction between northern and southern East Asians, but more than that – a geographic structure can be discerned in the boughs, branches and twigs of the East Asian mtDNA tree.4

  But as well as the mitochondrial genetic evidence for a general migration from south to north, there are lineages in northern East Asia – particularly C and Z – that are missing in the south. So where have these come from? Stephen Oppenheimer5 traces these lineages back to India, to early Asians who had skirted the western end of the Himalayas to reach the Russian Altai and populate Siberia between 40,000 and 50,000 years ago, leaving archaeological traces at places like Kara-Bom. The Y chromosome evidence mirrors the mtDNA phylogeography, with the North Asian founder population splitting east and west. Some headed west to Europe, while the eastward-bound colonisers continued following the mammoth steppe all the way into what is now northern China. Some remarkable details emerge from the complicated, over-written palimpsest: among the Ainu of Japan, a mitochondrial haplogroup called Y1 seems to record a specific migration from north-east Siberia into the northern Japanese islands.6 And the north-east Asian populations share lineages, like C, with Native Americans – but that is the subject of another chapter entirely.

  So it seemed that the East Asians were indeed descendants of the South-East Asian beachcombers, except for a few lineages that had made their way east from Central and northern Asia. Also on the Y chromosome, the M130 marker seems to record a migration along the South-East Asian coast, turning north to Japan, and there are a scattering of archaeological sites in Korea and Japan dating to around 37,000 to 40,000 years ago that may record this wave of colonisation.7

  I wondered if Jin Li had any thoughts on the origin of East Asian features, and whether genetics could yet shed any light on the development of these specific facial characteristics. Although he thought they may have first arisen in South-East Asians, perhaps around the LGM, he was also sceptical about any association with cold adaptation. Another hypothesis puts the origin and spread of East Asian features down to expansion of Neolithic populations with the advent of rice farming, but that didn’t seem to fit with the suggested timing of the mutations either.

  Li Jin wanted to pin down the relationship between genes and facial morphology – something that might help him answer where and how East Asian features arose and spread.

  ‘We don’t know what features are determined by which genes. We are just starting to try to identify the genes underlying morphological variation, and then we should be able to tell when exactly these features developed as well.’

  He was about to embark on what sounded like an extraordinarily ambitious project: to relate genetics to morphology by collecting anthropomorphic data from living people – effectively measuring them up – and using whole genome sequencing to look for genes or patterns of genes that seemed to be associated with particular features.

  ‘We’re looking at a thousand people, recording their morphological features – and we’re in the process of doing whole genome scanning.’

  This was just the sort of research that would start to fill in that vast gap in our understanding, building a bridge between genetics and morphology. And there were already some results …

  ‘We already know which genes underlie the orientation of hair whorls,’ said Jin grandly, but with a wry smile.

  It was clear that Jin Li was hugely excited by the potential of genetics to delve into the deep past and tackle the questions of origins of modern humans and modern Chinese. I was incredibly impressed by his open-mindedness and objectivity: surely the mark of a true scientist. And it was clear that the scientists at Fudan University were operating in a culture of academic freedom. In a country where regional continuity was still a ‘fact’ taught to schoolchildren and endorsed by the state, Li had been able to publish evidence for a recent African origin of East Asians.

  We walked out of the Institute of Genetics and across a garden dominated by a large statue of Chairman Mao. It seemed ironic. The poorly proportioned figure had been erected by students and Red Guards in 1966, but he was presiding over a very different cultural revolution now. Academic and individual freedom seemed to be winning back some ground.

  Pottery and Rice: Guilin and Long Ji, China

  Throughout prehistory, human populations have contracted and expanded, pushing into new territories and then withdrawing, largely under the influence of climate change. But three major episodes of Stone Age ‘mi
grations’ or population movements of modern humans can be discerned amid the general oscillations and milling about: the initial spread across and out of Africa, resettlement of great areas of the northern hemisphere after the end of the Ice Age, and the spread of expanding populations after the invention of farming.1

  The ‘Neolithic revolution’ and the origin of agriculture in the East was independent of that in Europe. Just as in the West, the East Asian farmers were more successful than hunter-gatherers at a population level (if not really at the level of the health and longevity of individuals). Higher levels of food production supported growing populations, and agriculturalists spread out of their homeland, carrying their languages and lifestyles with them. Indeed, some archaeologists have argued that the facial – and dental – characteristics of East Asians are so recent that they reflect that dispersal of a quickly expanding population of rice farmers as the Neolithic got under way in the East.2, 3

  It seems that the ‘Neolithic package’ of settlement, farming and pottery didn’t just suddenly spring into existence: the elements we recognise as being characteristic of the Neolithic way of life emerged in a mosaic fashion. In the East, one of the first elements to appear was pottery, pre-dating the development of farming. From the 1960s onwards, it was thought that the earliest pots in the world belonged to the Jomon culture of Japan, dating to nearly 13,000 years ago. But new archaeological evidence suggests that pottery may also have appeared at this time, and independently, in the Russian Far East and in south China.4

  In the late Pleistocene and early Holocene of south China, between 14,000 and 9,000 years ago, a culture appears which is characterised by grinding stones, shell and bone tools – and the earliest pottery. Some archaeologists have called it ‘Mesolithic’, comparing it with the same period in Europe; others prefer ‘pre-Neolithic’. I visited Guilin, in Guangxi Province, to see the oldest known pot in China.