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Prehistoric World

Ancient Human Unearthed in China

BBC News, 2 April 2007. Updated 15 April 2017

The remains of one of the earliest modern humans to inhabit eastern Asia were unearthed in a cave in China in 2006.

It was hoped that the find would shed light on how our ancestors colonised the East, a movement that is only poorly understood by anthropologists. Researchers found 34 bone fragments belonging to a single individual at the Tianyuan Cave, near Beijing.

Details of the discovery appeared in Proceedings of the National Academy of Sciences journal, with co-author Professor Erik Trinkaus, from Washington University in St Louis, USA reporting on them. Radiocarbon dates, obtained directly from the bones, showed that the person concerned lived between 42,000 and 39,000 years ago.

For this time period, which is critical for understanding the spread of modern humans around the world, there now existed two well-dated human fossils from eastern Asia. The first of these were the remains from the Niah Cave at Sarawak on Borneo, and now there was this specimen from China. Heading west, the next specimens at the time were attributed to Lebanon. There was nothing in-between.

Interbreeding theory

According to the 'Out of Africa' theory, modern humans (Homo sapiens) evolved in East Africa and then spread out across the globe about 70,000 years ago, replacing earlier, or archaic, human populations, such as Neanderthals in the west or Homo erectus in the east, with very little, if any, interbreeding.

The Tianyuan remains displayed diagnostic features of modern H sapiens. But co-author Erik Trinkaus and his colleagues argued, controversially, that the bones also displayed features which are characteristic of earlier human species, such as relatively large front teeth. The most likely explanation, they argued, is interbreeding between early modern humans emerging from Africa and the archaic populations they encountered in Europe and Asia.

Homo floresiensis
For a long time until the first decade of the twenty-first century, experts refuted the theory that modern humans had interbred with their cousins (such as Homo erectus in Asia, shown here), but evidence continued to mount in support of the theory, and DNA testing has proven that eastern populations were even more prone to it than were western ones


The pattern they saw appearing across the Old World basically involved a modern human in terms of its newly emerged characteristics, but also a minority of traits that were absent or lost in the earliest modern humans in East Africa. The question is where did they get these new characteristics from. Either they re-evolved them, which was not very likely, or to some degree they interbred with archaic groups.

Evidence from the animal world suggested that two closely related species, which had been separate for less than two million years, could interbreed successfully when given the opportunity to mate. One example of this from the UK was the Scottish wildcat, which is being absorbed into domestic cat populations through interbreeding. The domestic cat and the wildcat are distinct species separated by hundreds of thousands, if not millions, of years, and have very different body sizes. Despite this, pairings produce fertile, viable offspring.

Signs of disease

This view of interbreeding between Homo sapiens and archaic humans was controversial at the time. Other palaeoanthropologists were stating that some of these features were simply being retained from ancient African ancestors.

Most genetic evidence gathered from present-day humans by 2006 did not appear to support significant interbreeding between modern humans from Africa and archaics, although it eventually would. However, the researchers' analysis of the bones has revealed several interesting details about the Tianyuan individual's lifestyle.

The person's age at death was estimated by how much the teeth had worn down. This put them in their late forties or fifties. But the lack of a pelvis among the remains meant that it was not possible to say with any certainty what sex the individual was. The Tianyuan specimen showed several signs of disease. The individual had lost a number of their teeth before death - not unusual considering their age.

The researchers also identified several lesions on the leg bones which appeared to have been caused by a condition affecting the muscle attachments around both knees. Whatever condition these were caused by, however, it did not appear to have disabled the person, because the remainder of the leg bones suggest that this person remained active.

The single toe bone which was unearthed seemed to suggest that the individual wore shoes, pushing back the earliest known evidence for footwear by about 10,000 years. An earlier study by Professor Trinkaus showed that human small toes became weaker during the stage of prehistory known as the Upper Palaeolithic, and that this can probably be attributed to the adoption of sturdy shoes.

The invention of rugged shoes reduced humans' reliance on strong, flexile toes to grip and balance.

 

 

     
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