How real is the DNA evidence?

22 Aug 2011

At www.semioticon.com/frontline/bednarik.htm there is another article by Robert Bednarik, on beads and symbolism and the fact that Homo erectus in all likelihood had the capability to make them and make use of them (the same article or something very similar was published in Time and Mind two years ago). In doing so he outlines his opposition to the Out of Africa hypothesis - the idea of an African 'Eve' that gave birth to modern humans, Homo sapiens sapiens. They duly spread around the world in the Late Pleistocene - a wholly unsound idea he thinks. He opposes in particular the idea that these people were genetically superior to their contemporaries - and forebears (such as the Neanderthals and Homo erectus), and the idea that all extent human populations originate from a small ancestral population from a small part of Africa and especially the idea that all modern humans, no matter how diverse, are descended from a single female, known as Eve. As such, modern humans, Homo sapiens sapiens, are assumed to be the only humans that have been able to rise above a sub-human status. Only they are gifted with intelligence, the logic to resolve technical problems, are capable of abstract ideas and are able to produce whatever we might think art amounts to. He says at first sight the Out of Africa hypothesis has the appearance of a harmless origin in mythic or religious doctrine but he says it cannot support a realistic model of demographic population dynamics. In addition, it is far from harmless as it is capable of underpinning and legitimising ideologies. The idea of a pristine human origin has obvious political parallels, especially when bias and preconceptions are used to undermine the attainments of the other groups.

Bednarik is not a product of the educational conveyor belt system and he only became interested in archaeology and anthropology after he took early retirement - following a career in business. He brought a fresh perspective to the past but admits that Out of Africa is the current dogma and dictates research directions and priorities - and marginalises ideas outside the box. Bednarik claims Out of Africa is based on a controversial proposition made by some genetic scientists - but opposed by others. The former have gained the high ground - for the present. Bednarik says there is no archaeological evidence to support the Out of Africa theory - which may account for recent desperate attempts to find evidence of tools in southern Arabia, the assumed route to India and SE Asia. The genetic evidence is the key, it would seem, and genetics are, it seems to me (not Bednarik) currently accepted too easily without enough scepticism. It is in fact reminiscent with what went on when the C14 dating methodology first hit geology and archaeology. All the old dating systems went out of the window, from pottery sequences to counting lake varves. It was only after 20 years or so, after a mountain of anomalies piled up that the authorities would accept there was something wrong with the C14 process. Calibration and refined methodology eventually brought order to the situation - and it may be that DNA evidence will eventually have to be reined in to some extent - especially when it comes to periods in the remoter past. 

In genetics, different teams produced different genetic distances in nuclear DNA - the distances created by allele frequencies that differ between populations. Bednarik provides a critique of genetics, mainly with evidence from the 1990s (which suggests the time when the article was written). However, it was in the 1990s that the Out of Africa hypothesis became dominant.

Bednarik says that the idea relies on distinct uniformitarian principles. These are assumptions made on a neutral mutation rate and a constant effective population size. These are the two variables that determine the outcome of all the calculations. Once again, a comparison with C14 can be made which relied on the fact that it was assumed a constant rate of arrival in the atmosphere. It is now accepted it was not strictly constant - but varied over time. We may have to wait until geneticists recognise those constants central to their answers may not be as constant as they assume.