In a lecture delivered to the American Society for Human Genetics, paleo-anthropologist John Hawks gives a lucid summary of the African record of human evolution. The divergence of the hominin lineage from other apes took place in Africa between 5 and 10 million years ago. Hominins began dispersing out of Africa in pulses beginning 2 million years ago. The vast majority of hominins though continued to live and evolve in Africa. Yet, popular stories of human evolution focus on people leaving Africa and colonizing the world. What has been happening in Africa all along gets sidelined in this narrative.
The “out of Africa” slogan came from well-intentioned scientists. They thought that by emphasizing the idea of an African origin, they would send a clear message that Africa had an important place in evolutionary narratives. That much is true. Africa was the center of human origins. But “out of Africa” stories focused almost exclusively on dispersal, as if it were an exodus. Africa’s place in these stories was the place that people left.
John Hawks refocuses our attention on the African fossil and genetic record that tells us that Africa always has occupied a central place in our evolutionary story.
He points out that this record has yielded three big insights:
First, modern humans did not originate in a bottleneck after 200,000 years ago. Our origin was much deeper in time than this.
Second, our species originated in Africa from deeply structured ancestral populations. These were much more different from each other than any human populations are today. We do not know how they interacted or which gave rise to living peoples.
Third, some of these deeply divergent populations survived in Africa until recent times. During the time of human origins, “modern” humans were not alone.
The term bottleneck means that at some time in our past there was a drastic reduction in our population size and genetic variability.
Anyone interested in the topic of human evolution should read this article.
The “out of Africa” slogan came from well-intentioned scientists. They thought that by emphasizing the idea of an African origin, they would send a clear message that Africa had an important place in evolutionary narratives. That much is true. Africa was the center of human origins. But “out of Africa” stories focused almost exclusively on dispersal, as if it were an exodus. Africa’s place in these stories was the place that people left.
John Hawks refocuses our attention on the African fossil and genetic record that tells us that Africa always has occupied a central place in our evolutionary story.
He points out that this record has yielded three big insights:
First, modern humans did not originate in a bottleneck after 200,000 years ago. Our origin was much deeper in time than this.
Second, our species originated in Africa from deeply structured ancestral populations. These were much more different from each other than any human populations are today. We do not know how they interacted or which gave rise to living peoples.
Third, some of these deeply divergent populations survived in Africa until recent times. During the time of human origins, “modern” humans were not alone.
The term bottleneck means that at some time in our past there was a drastic reduction in our population size and genetic variability.
Anyone interested in the topic of human evolution should read this article.
Many, many thanks for this Suvrat. Why is it that with most of your posts, I end up feeling I really needed to read this?
ReplyDeletethanks Theo.. I guess our interests match! :)
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