One of the most remarkable achievements of early humans (Homo ergaster aka H. erectus) was not their tools, but their migration out of Africa around 1.8 Ma, to reach as far as Indonesia and China. There is no evidence for that feat having occurred again until fully modern humans arrived in east Asia about 70 ka ago. The toolkit of Asian “Action Man” is unimpressive, in the sense that it resembles the slightly reshaped broken pebbles of the Oldowan culture, that first appears in the African archaeological record about 2.4 Ma ago. Development in Africa of the enigmatic and beautiful bi-face or Acheulean axe was after the first Asians had departed, around 1.5 Ma. So what were these early wanderers like; what did they want? The decade-long work in China by Noel Boaz, an anatomist from the Ross School of Medicine in New Jersey and anthropologist Russell Ciochon of the University of Iowa will soon appear in their book Dragon Bone Hill, an Ice-Age Saga of Homo Erectus (Oxford University Press), which they preview in the 17 April 2004 issue of New Scientist (p. 32-35). Boaz and Ciochon have worked mainly in Zhoukoudian near Beijing, a major resource for human remains whose different levels extend back to about 800 thousand years. Another site in China, Longouppo, contains disputed remains as old as 1.8 Ma, as are Dubois’ famous discoveries of the type specimens of H. erectus by the Solo River in Java. From the time when Zhoukoudian became famous among Chinese apothecaries as a source of “dragon’s bones” (a mixture of human and other animal remains) there has always been an air of myth about the findings there – a permanent dwelling for hundreds of thousand years, protected from glacial temperature falls by the consistent use of fire. In essence, the publicised view is that “Peking Man” led a cosy hearthside existence for a very long time indeed. Boaz and Ciochon tell a different, and more mundane story. Most bones in the deposit are those of a great variety of other animals, with disproportionately few of human origin, and those are highly fragmented. The dominant species is a giant hyena, and many of the bones, including humans, are well gnawed, which is what hyenas do especially well. There are occasional signs of human occupation and use of fire. The human remains are encased in layered carbonate flowstone,. Records of fluctuating d18O from that matrix, matched against the global time series of climate change, show that occupation was only during interglacials – the site was abandoned or unvisited during the depth of glacial periods. Some animal bones show cut marks made by stone tools, and it is more likely that H. erectus raided to get remnants of other beasts’ kills, perhaps using fire, rather than being top of the predatory order. The great surprise throughout Asia is the complete lack of development of stone tools from the primitive culture that arrived there, until as late as 20 to 30 thousand years ago, when Asian H. erectus vanished. Apart from the stunning breakthrough to the bi-face axe, African erects also had a million-year long cultural stasis – resting on laurels with a vengeance. Finally, from a number of skulls at Zhoukodian, Boaz and Ciochon have shown signs of trauma. These are depression fractures, probably not necessarily fatal, but indicate sharp blows to the head with blunt instruments. Their interpretation is that the Chinese erects settled disputes by bashing heads; so that aspect of culture has not changed a lot since. Their story is not “politically correct”, but with publication of their book, other palaeoanthropologists can judge it on the basis of the evidence from Dragon Bone Hill.
Faster development of Neanderthals
Go to any horse sale and you will see bidders closely studying the teeth of their prospective purchases; the origin of the saying, “Never look a gift horse in the mouth”. Teeth show growth ridges, and in grazing animals they are prominent, so that it is possible to judge the age of a horse easily and accurately. Human teeth are different only in the less obvious signs of growth. Microscopic examination reveals such records, down to the daily level, although the most prominent features are curious disturbances in their deposition that form approximately weekly. They appear as ridges on the crowns of teeth. The variable spacing of these perikymata provides a record of the pace at which adult teeth develop. In modern humans the spacing becomes very much closer in the later growth history (towards the tooth’s cutting edge) than in its early stages, and reflects the slow development to full adult dentition. In a painstaking study of hundreds of teeth from Cro Magnon and Neanderthal teeth, Fernando Rozzi of the University of Paris and José Bermudez de Castro of the Spanish National Museum of Natural Sciences have discovered an odd difference in the development rates of Neanderthals (Rozzi, F.V.R & Bermudez de Castro, J.M. 2004. Surprisingly rapid growth in Neanderthals. Nature, v. 428, p. 936-939). The late perikymata of Neanderthals are more widely spaced than in Cro Magnon and modern humans, strongly suggesting that Neanderthals developed to adulthood by about the age of 15, three to five years earlier than us and our immediate ancestors. As well as confirming that they are a separate species, the results suggest that Neanderthals, while acquiring brains as large, and in some cases even larger than ours, had evolved more rapid maturation and probably a genetically determined shorter adult life. This would have had some effect on transfer of culture, which in human societies is often the most important value of elderly folk. The fewer samples of teeth of earlier human species (H. heidelbergensis and H. antecessor) reveal an even greater surprise. They are more like modern human teeth (albeit with signs of somewhat faster growth), which suggests that evolution of the Neanderthals involved a regression. The authors suggest that the combination of a backward step to faster development with rapid brain growth to large size might reflect a very-high calorie diet together with adverse environmental conditions.