Evolution News - On the Origin of Our Species

This cranium from Jebel Irhoud in Morocco is often called a modern human ancestor. The meaning of that ancestry is discussed and disentangled in a new study by Bergstrom and colleagues.

© Chris Stringer

On the Origin of Our Species | Max Planck Institute for the Science of Human History

As I have said before, despite Creationist fraudulent assertions that there are no transitional fossils in the human ancestral lineage, the reality is that there are, if anything too many of them. This has led to a confusing picture and a 'tree' more resembling of a bush than a neat tree with nicely spaced-out branches. But then nature has no obligation to provide us with neat, easy to understand data, especially when the reality is fuzzy and complicated.

Now a group of paleoanthropologists from the Natural History Museum, London, UKThe Francis Crick Institute, London, UK and the Max Planck Institute for the Science of Human History, Jena, Germany have joined forces to try to sort out the confusion and debunk a few misunderstanding that have arisen, even in scientific circles.

The Max Planck Institute news release explains:

Co-author researcher at the Natural History Museum Prof Chris Stringer said: “Some of our ancestors will have lived in groups or populations that can be identified in the fossil record, whereas very little will be known about others. Over the next decade, growing recognition of our complex origins should expand the geographic focus of paleoanthropological fieldwork to regions previously considered peripheral to our evolution, such as Central and West Africa, the Indian subcontinent and Southeast Asia.”

The study identified three key phases in our ancestry that are surrounded by major questions, and which will be frontiers in coming research. From the worldwide expansion of modern humans about 40-60 thousand years ago and the last known contacts with archaic groups such as the Neanderthals and Denisovans, to an African origin of modern human diversity about 60-300,000 years ago, and finally the complex separation of modern human ancestors from archaic human groups about 300,000 to 1 million years ago.

The scientists argue that no specific point in time can currently be identified when modern human ancestry was confined to a limited birthplace, and that the known patterns of the first appearance of anatomical or behavioural traits that are often used to define Homo sapiens fit a range of evolutionary histories.

Co-author Pontus Skoglund from The Francis Crick Institute said: “Contrary to what many believe, neither the genetic or fossil record have so far revealed a defined time and place for the origin of our species. Such a point in time, when the majority of our ancestry was found in a small geographic region and the traits we associate with our species appeared, may not have existed. For now, it would be useful to move away from the idea of a single time and place of origin.”

Sadly, the team's publication in Nature is behind an expensive paywall. In their abstract, the authors say:

We argue that no specific point in time can currently be identified at which modern human ancestry was confined to a limited birthplace, and that patterns of the first appearance of anatomical or behavioural traits that are used to define Homo sapiens are consistent with a range of evolutionary histories.

This, of course, is consistent with the emerging picture of human origins of a widespread species, evolving in relative isolation into emerging species, then remixing to for a single complex of regional varieties, rather like a ring-species of related species, subspecies and geographical varieties, exactly what you might expect from an evolutionary process across a wide geographical distribution.

This did not stop when anatomically modern humans emerged from Africa to come up against the descendants of earlier radiations in Eurasia, where they interbred with Neanderthals, Denisovans and probably a third, as yet unidentified, hominin.

So, no founder species from one location, as would be nice and neat, but an origin in hybrids and the regular remixing after partial or near-complete speciation.

Again, the science refutes the absurdly childish Creationist origin myth of the entire human population being descended from a single founder couple who were magicked into existence without ancestors, by magic, or the even more absurdly childish notion of us all being descended from eight survivors of a global genocidal flood a few thousand years ago.

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