Carina Schlebusch led a team of researchers at Uppsala University in Sweden in a project combining genome mapping with anthropology in an effort to uncover genetic links between modern African populations and their ancestors. The findings may have unexpected implications for the early history of Homo sapiens, the modern humans.
Until now scientific consensus has placed the moment our species split off, as a genetically distinct and anatomically modern variant, at 200,000 years ago. The new evidence suggests the true split may have actually occurred between 260,000 and 350,000 years ago. The study was initially published in the Science journal.
genetics and archaeology continues to prove promising in helping us unravel our species’ complex history!
150,000 years is a significant jump in time! There has been tentative fossil evidence that pointed to a possible early Homo sapiens split – namely 300,000-year-old fossils found in Northwestern Africa and the 260,000-year-old Florisbad Skull in South Africa – but these remains exhibited slight anatomical differences to modern humans and so were considered predecessors.
The September 28th study led by Schlebusch has been the first that, by sequencing the genome of seven individuals who lived are between 300 and 2000 years ago, has managed to provide more convincing evidence of earlier origin. They compared these genomes with modern Khoe-san populations of South Africa as well as with ancient Stone Age hunter-gatherer genomes in order to map the timeline showing human groups splitting off from each other.
One method of dating the splits, according to Seeker, is to look at the number of DNA mutations; “if we assume that DNA mutations occur in a clock-like manner, one can date when these populations or individuals split from each other”, said Schlebusch.
This research illustrates that the Khoe-san people are the oldest branch on the human family tree (broke off from main branch 260,000 years ago, then split in two again 200,000 years ago) and, due to their early split, are the most genetically diverse human population on the planet. The reason this has not been apparent until now is because the ancestors of the Khoe-san people interbred with migrant farmer groups who came from East Africa to South Africa, having already interbred with other populations throughout the past 2000 years.
Having a fossil dated before this genetic mixing occurred allowed the researchers to accurately map the groups’ ancestry.
The history of how we became modern humans is especially messy. We did not evolve in one spot, but rather in multiple places simultaneously; “we see this gradual transition from archaic to modern forms in North, East, and southern Africa, and fossils of modern, transitional and archaic forms are found in all three of these regions,” Schlebusch said. The accepted chronology is that Homo erectus evolved into Homo heidelbergensis, which evolved into Homo sapiens in Africa, Neanderthals in Europe and West Asia, and Denisovans in East Asia. Homo sapiens then moved out of Africa, into Eurasia, wiping out as well as mating with populations such as Neanderthals or Denisovans.
Such genetic heritage variants, however small, can still exhibit adaptations, like resistance to higher altitudes or certain diseases, in modern day humans.
150,000 years is a significant jump in time!
The relationship between genetics and archaeology continues to prove promising in helping us unravel our species’ complex and chaotic African history and highlight our evolutionary past. The findings are still incredibly new and the scientific jury is still out on whether they are robust enough – as stated by scientist, anthropologist Todd Disotell at NYU, who said he is skeptical of the study’s conclusion. Regardless, this could just be the beginning as, according to Seeker, Schlebusch stated that the group is working on “several other African genetic projects involving modern day and Ancient Africans”; additional evidence may yet be revealed.
If you want to read more about studies involoving genomes and genetics give READ THIS where Alina Ivan looks at new research and guidelines relating to gene altering in foetuses and its possible medical uses…