Researchers shed new light on the origins of modern humans
Researchers from the University of Huddersfield, with colleagues from the University of Cambridge and the University of Minho in Braga, have been using a genetic approach to tackle one of the most intractable questions of all – how and when we became truly human.
Modern Homo sapiens first arose in Africa more than 300,000 years ago, but there is great controversy amongst scholars about whether the earliest such people would have been ‘just like us’ in their mental capacities – in the sense that, if they were brought up in a family from Yorkshire today, for example, would they be indistinguishable from the rest of the population? Nevertheless, archaeologists believe that people very like us were living in small communities in an Ice Age refuge on the South African coast by at least 100,000 years ago.
Between around 100,000 and 70,000 years ago, these people left plentiful evidence that they were thinking and behaving like modern humans – evidence for symbolism, such as the use of pigments (probably for body painting), drawings and engravings, shell beads, and tiny stone tools called microliths that might have been part of bows and arrows. Some of this evidence for what some archaeologists call “modern human behaviour” goes back even further, to more than 150,000 years.
The Huddersfield-Minho team of geneticists, led by Professor Martin Richards at Huddersfield and Dr Pedro Soares in Braga, along with the eminent Cambridge archaeologist Professor Sir Paul Mellars, have studied the maternally-inherited mitochondrial DNA from Africans in unprecedented detail, and have identified a clear signal of a small-scale migration from South Africa to East Africa that took place at just that time, around 65,000 years ago. The signal is only evident today in the mitochondrial DNA. In the rest of the genome, it seems to have been eroded away to nothing by recombination – the reshuffling of chromosomal genes between parents every generation, which doesn’t affect the mitochondrial DNA – in the intervening millennia.
The migration signal makes good sense in terms of climate. For most of the last few hundred years, different parts of Africa have been out of step with each other in terms of the aridity of the climate. Only for a brief period at 60,000-70,000 years ago was there a window during which the continent as a whole experienced sufficient moisture to open up a corridor between the south and the east. And intriguingly, it was around 65,000 years ago that some of the signs of symbolism and technological complexity seen earlier in South Africa start to appear in the east.
In any case, it looks as if something happened when the groups from the South encountered the East, with the upshot being the greatest diaspora of Homo sapiens ever known – both throughout Africa and out of Africa to settle much of Eurasia and as far as Australia within the space of only a few thousand years.