The Incredible Human Journey

by Alice Roberts

  We awoke in a cold tent. The temperature inside the tents quickly dropped to match the ambient temperature outside as soon as the life-giving stove burned out. But before long Marina’s husband had coaxed the stove back to life and I could contemplate emerging from my sleeping bag and getting layered up, ready to step outside. It felt warmer again, but it was hard to tell if this was a real change in external conditions or if I was acclimatising to my new environment. Certainly, I was now out and about in –20 degrees, thinking how pleasantly mild it was, very different from my initial reaction to the same temperature when I had stepped off the plane in Yakutsk. But the Evenki were walking around in far fewer layers than their recently acquired and rather less self-sufficient companion. Many of the snowmobile drivers on the journey to the camp had kept their heads covered with reindeer hoods but their faces had been bare the entire way.

  Cold adaptation in humans is a tricky subject. It’s very difficult to be sure if what you’re looking at in terms of anatomy is an adaptation to, rather than a consequence of, an environment. Short stature and limbs certainly make sense in a cold climate as this reduces the surface area to volume ratio, making it easier to keep body warmth in. But short stature may also be the result of cold stress as the body is growing, in other words, a by-product of cold rather than an adaptation to it. Short limbs, though, may be a true anatomical-physiological adaptation to low environmental temperatures: something which is inherited rather than acquired as a child grows.

  In the 1960s the anthropologist Carlton Coon and others proposed that facial characteristics such as narrowed eyes, epicanthic folds, small noses and broad, flat faces – i.e. East Asian, or what were then described as ‘Mongoloid’ features – were specific cold adaptations, protecting the eyes and creating fewer projecting ‘corners’ to get cold. But at the other end of the landmass, large noses are put forward as cold adaptations in Neanderthals and modern Europeans, designed to warm icy air before it’s drawn into the lungs. And if East Asian features are cold adaptations, why haven’t northern Europeans ended up looking the same? The theory starts to look decidedly shaky.

  It seems unlikely to me that the environment could have been such a powerful sculptor of our bodies and faces when a fundamental characteristic of modern humans is the use of culture to buffer ourselves from such pressures. Being able to sew fur together to create protection from the elements would have been essential for the initial colonisation of northern Siberia, as it clearly still was for day-to-day survival in this extreme environment. Looking at the poor little girl who had ridden in on a sledge the same night as me, with an enormous chilblain blister on her right cheek, it was also clear that the Evenki were not immune from the cold. And, beyond intuition and anecdote, various researchers have presented anatomical and physiological evidence to show that East Asian faces cannot be the result of cold adaptation. Steegman published a series of papers along these lines in the sixties and seventies, including a report of a physiological study where he had compared the surface temperature of the face in Japanese and European people, at zero degrees, and found absolutely no difference in the thermal responses;10 indeed, he wrote, ‘If anything, the thin and hawk-like visage of the European is better protected from cold than that of the Asiatic.’ Evolutionary biologist Brian Shea11 looked at the facial anatomy of Eskimos; he suggested that the internal architecture of the nose and sinuses might show some evidence of cold adaptation, but concluded that there was nothing to support the general idea of Asian faces being ‘cold-engineered’.

  Having eliminated cold adaptation, we are still left with the question of why (or indeed where and when) typically East Asian features arose. I will return to these questions later in this chapter, with the fossil and genetic evidence that I explored in China.

  Staying with cold adaptation for a minute, though, there does seem to be some interesting recent research suggesting that there may be some adaptive changes in northern populations – not in faces, but deep inside cells. There are very few examples of definite Darwinian or genetic adaptations among modern humans. Sickle cell anaemia and Stephen Oppenheimer’s thalassaemia in South-East Asian populations are rare examples, and the links in the chain are understood: the gene(s) responsible, the effect on phenotype (the observable characteristics: in these examples, the effect on blood), and the way in which a mutation confers its selective advantage (protection against malaria infection in these cases).

  The boosting of thyroid hormones and metabolic rate discussed earlier is a short-term, physiological mechanism that allows the body to effectively turn excess food into heat, not an example of a Darwinian adaptation to cold. The proposed genetic adaptation to the cold is related to the efficiency of mitochondria. In these minute ‘power stations’, of which there are thousands per cell, dietary calories are transformed into a package of energy that can be used by the cell (adenosine triphosphate, or ATP). Mitochondrial DNA contains the genes coding for just thirteen proteins, all of which are employed in energy production. Doug Wallace of the University of California, aficionado of all things mitochondrial, has studied how genetic mutations in mtDNA could alter the efficiency of mitochondria. A less efficient system produces less ATP per calorie, and loses energy as heat. So here comes the adaptation: Wallace argues that, in the tropics, mitochondria tend to be very efficient and generate little heat, whereas, in the Arctic, mutations make the mitochondria less efficient, and they produce heat.12

  So while I was relying on chemical reactions inside bags of hand-warmer granules to keep my fingers going, it seems that the Evenki may have been benefiting from their own internal heat generation. And the short-term physiological response stimulated by the Evenki’s meaty diet would have further amplified that effect: thyroid hormones mainly work on mitochondria. Native Siberians have higher metabolic rates than non-natives on a similar diet. Even if I’d eschewed my vegetarianism and eaten reindeer meat, I still wouldn’t have been able to compete in the production of metabolic warmth.

  It does seem that modern humans are the only hominins to have colonised the Arctic and subarctic regions of the far north. This feat of survival may have depended on a whole range of adaptations, biological, behavioural and cultural, which together made it possible for humans to flourish in Siberia, and heat-generating mitochondria may be among those adaptations. But one other adaptation seems even more important: it was reindeer hunting, providing a meat-rich diet and fur for cold-weather clothing, that paved the way for colonisation of the north.

  Back to the Evenki, and the camp was getting busy as the brigade prepared to move house. It was remarkable how quickly a chum could be taken apart and packed up ready to be moved off on reindeer-drawn sledges. Once the stove had been dismantled and taken away, it was time to start on the tent itself. I helped to untie the leather strips holding the reindeer-hide covering on to the larch skeleton of the chum. Tricky little knots involved removing my gloves to work with bare fingers for a few minutes each time before the cold got to my fingertips and I had to plunge them back into my mitts to recover. Nevertheless, the hides came off quickly and we then folded them up and tied them on to sledges. Then the tepee-like framework of larch poles was taken apart. All the poles were simply resting together, apart from the final three, which were tied at the top to create a tripod, which gave the chum its strength. These were toppled and separated, and then all that was left was the floor of larch branches. It was interesting to reflect that there would be no archaeological trace of this temporary dwelling.

  The twenty-foot larch poles were tied up and attached to the back of sledges, and we were ready to set off: a caravan of reindeer sledges moving through a snowy landscape. The female leaders of the herd had been lassoed and came with us on the caravan, and as I looked back along the snowy valley my eyes met an extraordinary sight. The entire herd was following us, surging like a great wave through the woods. You could hardly separate individuals: it was like a flood of fur, hooves and antlers, flowing down the valley behind us. And thi
s, of course, was the whole point of the nomadic lifestyle of the Evenki: their reindeer needed to migrate, to move on to fresh pastures, however strange it may have seemed to think of the lichen buried beneath the snow as ‘pasture’. But as soon as we stopped the herd was busy digging down through the snow with hooves to get at their food. Piers said it was difficult to work out who was leading whom. The reindeer herd periodically felt the urge to migrate; their human companions needed to anticipate this and direct their movement accordingly

  At a new site we dug out a circle of snow with wooden spades, and the air was full of the smell of freshly cut larch as small trees were brought over and stripped of their branches to create a floor for the chum. The three foundation poles went up first, and then more poles laid up against them, about twenty in all. Then we unfolded the hides and tied them in place. Reindeer skins were spread on the larch branches inside. Just ten minutes later, we had something that looked like home.

  But having nomadised with the Evenki, it was time to continue my own migration. The temperature was dropping by the day and Vasily advised us to travel out that afternoon, so Piers, Anatoly and I packed up and readied ourselves for the snowmobile caravan again. This time, in daylight, it was much warmer than the trip out (this was relative by now: it was still less than –20 degrees), and I even risked going without goggles. Riding, facing backwards, on the sledge, I waved to the Evenki children as we left the camp, and had one last view of the reindeer herd among the trees, and then we were off into the woods and snow. The landscape was beautiful: we rode for a long time in a valley alongside pink cliffs, and I saw rolling snow-clad hills stretching off into the distance. Eventually, the windows of Olenek came into view, shining out in the distance like a cluster of beacons, reflecting the orange light of the setting sun.

  Before flying out, I spent one more night in the village, at Marina Stepanova’s once again. And just before I left the following morning, the other Marina, head of the reindeer herders, who had travelled back with us, sniffed both my cheeks and gave me the reindeer boots as a gift.

  The Riddle of Peking Man: Beijing, China

  Having explored the genetic and archaeological evidence for the peopling of North Asia, and having experienced the deathly chill of the taiga for myself, it was time for a change of tack, to track down the first modern human East Asians. But in the Orient, I was going to be walking into one of the biggest controversies in palaeoanthropology, because the prevailing theory in China is that the modern Chinese are descended from Homo erectus in China. Chinese palaeoanthropologists claim that the available evidence supports regional continuity: an unbroken line of descent from the archaic humans that made it to East Asia over a million years ago, and they even claim that the features so characteristic of modern Chinese faces are already there in ancient Chinese Homo erectus fossils. This stands in direct opposition to the more widely accepted theory of a recent African origin for all anatomically modern humans, across the globe. Social scientist Barry Sautman has argued that the Chinese state has used palaeoanthropology in this way to support racial nationalism and foster a sense of ‘Chineseness’.1

  I left Russia, flying from Yakutsk to the severe, grey, end-of-the-world airport at Vladivostock, and on to Beijing. Once again I was meeting two great figures from the world of palaeoanthropology: one in the present and one from the deep past. I was to become acquainted with Professor Xingzhi Wu and Peking Man.

  The argument over Peking Man and the ancestry of the Chinese people has a long history, and progress in the debate has been stymied by a lack of open scientific communication between East and West, the language barrier further cemented by political tensions. Anthropologists from the West have had limited access to both specimens and ideas from China.2 But things are changing. There are now British and Canadian researchers working away on Chinese dinosaurs in the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) in Beijing, and Chinese researchers are publishing more and more in international journals.

  I met Professor Wu at Zhoukoudian, the place where the Peking Man fossils had been found. It felt as if I’d come on some sort of pilgrimage to one of the ancient places. Zhoukoudian is about 50km south-west of Beijing, in a landscape dominated by limestone massifs riddled with fissures and caves. In 1921, a Swedish geologist called John Gunnar Andersson was visiting Zhoukoudian, and a local resident took him to a cave that was reputed to be full of ‘dragon bones’. He realised that the bones of the mythical creatures were in fact fossils, and, throughout the 1920s and 1930s, extensive excavations were undertaken at the site by an international team of scientists. Ancient human teeth, and then parts of skulls, started to emerge from the ground, and the hominin was christened Sinanthropus pekinensis. The fossils have since been reclassified as Homo erectus, and the finds from Zhoukoudian represent the largest sample of specimens of this species from a single locality.

  Professor Wu led me through a tunnel-like cave into a deep, steep-sided pit on the side of Dragon-Bone Hill. I was amazed to find out that this pit, which was around 40m in depth, had been entirely dug out as an archaeological excavation. It must have been a mammoth undertaking. What was originally a cave in the side of the hill had filled up with sediments, and the roof had fallen in. As the archaeologists had dug down and down, they had found layers full of limestone blocks, fossils and stone tools. The first skull of Peking Man was found in layer 11, in sediments 20m below the surface.

  The skulls of what was then called Sinanthropus pekinensis (literally ‘Peking China-Man’, or, as it was to become known, Peking Man) were studied by the German anatomist Franz Weidenreich, who proposed that they represented ancestors of modern Chinese. To him, the ancient skulls possessed features that linked them with modern populations. Weidenreich took the fragments that had been recovered in the dig at Zhoukoudian, and, with his assistant Lucille Swan, made a reconstruction of an entire skull, which was to become the icon of the newly discovered species.3 The idea that Chinese people had a lineage stretching back a million years, in China, led Chinese archaeologist Lin Yan to proclaim that the Chinese are ‘the earth’s most ancient original inhabitants’.1

  Wu and I walked up, out of the pit of Locality 1, and up on to the north-east slope of Dragon-Bone Hill, where we could look down into the excavated Upper Cave, Shandingdong. In the 1930s, excavations in this area had yielded three well-preserved skulls of modern humans, as well as perforated animal teeth, pebbles and shells. The Upper Cave skulls were also examined and described by Weidenreich.

  Then, in late June 1937, Chinese and Japanese troops clashed in the town of Wanping, about thirty miles from Beijing, in what was to become known as the ‘Marco Polo Bridge Incident’, and effectively the beginning of the Second World War in the East. By the end of July, Beijing had fallen to the Japanese. Excavations at Zhoukoudian ceased, and the precious Peking Man fossils were packed up into crates to be sent for safe-keeping to America. But they never made it. The tragic loss of the Peking Man fossils is one of the great mysteries of palaeoanthropology. There are all sorts of stories about where the fossils may now reside (if indeed they still exist). Suggestions include the fossils having been removed to a museum in Taiwan, sent to the Crimea on a Russian ship, or having been kept in a hospital in Beijing.4 So, when I said I was to meet Peking Man, I was actually going to see casts of the original fossils.

  Professor Wu and I returned to Beijing, to the IVPP, where the casts of Peking Man and the Upper Cave skulls are kept. We entered a room where one wall was lined with lockers from floor to ceiling. A table covered in a deep red cloth stood in the centre of the room. But then we both had to leave the room and stand in the corridor while a security officer removed the specimens from the lockers.

  ‘I am not allowed to see the drawers out of which the skulls come. I will stand back and wait here.’ The location of the specimens was kept secret even from Professor Wu, such was the nature of this magnificently elaborate security system.

  ‘He keeps the key so t
hat nobody knows the number,’ said Professor Wu.

  ‘So you don’t know the number?’

  ‘No. I don’t want to know. If I know, and if it is lost, then I have the responsibility. But now I don’t know anything. I have no responsibility,’ Wu smiled.

  While we were waiting out in the corridor, I asked Professor Wu how he had become interested in palaeoanthropology. It turned out that he had qualified as a medical doctor, but that, at the time, China had needed more medical teachers, so he was instructed to become a lecturer in anatomy. Anatomy and palaeoanthropology have always been closely allied professions, and so when excavations restarted at Zhoukoudian in the 1950s, Wu naturally became involved.

  He asked me about my background, and I was really pleased to be able to tell him that I too had trained as a medical doctor, then became a lecturer in anatomy, and developed an interest in palaeoanthropology. I felt like an apprentice in the presence of a grand master. At the age of eighty, Professor Wu was still coming to work every day (on his bike) at the IVPP.

  Once the specimens were out of the lockers, we could re-enter the room. Six or seven of them now sat, neatly lined up, on the table. There were some modern human skulls, and casts of Homo erectus. I recognised the cast of the original Weidenreich/Swan reconstruction but I had also read about a newer reconstruction put together by Ian Tattersall and Gary Sawyer from the American Museum of Natural History, New York, and Professor Wu had arranged for this to be taken out as well. There were also two thick fragments from the top of a skull.

  ‘These are original fossils of Peking Man,’ he said. I was taken aback. I knew the story of the missing crates of fossils in the Second World War, and I had not expected to see any actual fossils, just casts.