Evolution and humans: all over Asia (Evolution)

by David Turell , Tuesday, September 12, 2023, 19:16 (436 days ago) @ dhw

A review of fossil evidence and possible migrations:

https://mail.google.com/mail/u/0/#inbox/FMfcgzGtwzsqMPVQnvJRVqcqVggDNQjx

"...eastern Asia was home to the Denisovans, while the island of Flores had the hobbits (Homo floresiensis) and the Philippines had Homo luzonensis. It’s often hypothesised, or even assumed, that H. erectus was the ancestor of all these populations, but we don’t have DNA from H. erectus so we don’t actually know.

"And then along came modern humans (Homo sapiens). Our species seems to have expanded from Africa in multiple waves: H. sapiens remains are known from Israel from 177,000 years ago and 120,000 years ago, but genetic evidence suggests most non-Africans today are descended from a migration out of Africa around 60,000 years ago. Other hominin groups vanish from the fossil record not long after.

"In other words, there were two main waves of migration from Africa to Asia. The first was Homo erectus, which then gave rise to a bunch of other groups. The second was Homo sapiens, which replaced all of them.

"Seems simple enough, right? The thing is, there’s a bunch of fossils from southern Asia that don’t neatly fit, and nobody is quite sure what to make of them.

"One of the studies from the aforementioned special issue describes a lower jawbone from Hualongdong, a cave in eastern China...we have pronounced chins and the Hualongdong jawbone doesn’t, and on other measures it looks like an older species. The overall mix of features is unique.

"The jawbone is about 300,000 years old. That’s a curious bit of timing, because it’s about when the oldest known Homo sapiens were living in what’s now Morocco, in northern Africa.

***

"if the Hualongdong jawbone really does belong to the same population as the Moroccan Homo sapiens, it would mean hominins made the journey from northern Africa to eastern China within a few tens of thousands of years. That’s surely possible but I would want to see evidence.

"An alternative explanation is that the Hualongdong jawbone is a case of convergent evolution: that is, the same features evolved independently in certain east Asian and African populations.

***

"There are lots of other hominin fossils from eastern Asia that are similarly odd. The Dali cranium from China is 260,000 years old and has also been (controversially) interpreted as early Homo sapiens. Other specimens don’t quite fit H. erectus or H. sapiens: some have old-looking shapes but lived recently, others look recent but are actually ancient. And we haven’t even got to the stone tool record, or instances of prehistoric art.

***

"The genetic evidence is unambiguous that our species hails from Africa: that conclusion was true in the 1990s and it’s only been strengthened by the swathes of genomic data we’ve obtained since. But that doesn’t mean the traffic was one way. Overall, yes, we come from Africa. But I’m now convinced there was a lot of back and forth.

***

"...maybe some of the features we now associate with Homo sapiens first evolved in southern Asia and were then carried into Africa by a westward migration – before being carried right back out of Africa and all around the world when our species went global. This would explain the Hualongdong and Dali remains, without contradicting the genetics.

***

"If there’s one simple thing we can draw out of all this, it may be that prehistoric populations were more connected than we imagine. We tend to think of prehistoric people living in isolated tribes, each with its own patch of land. But that isolation is partly a reflection of how hunter-gatherers live today, when agriculture has forced them to the fringes of society.

"In earlier times, the hunter-gatherer network spanned continents. I don’t mean that people living in modern Tanzania were personally acquainted with those living in what’s now Laos – clearly, they weren’t. But there was a long chain of communities linking them

***

"If that’s true, then once upon a time a new and advantageous gene variant could spread rapidly across thousands of kilometres, as people moved and intermarried. In other words, prehistory may have been globalised.

Comment: The conclusion is 315,000-year-old H. sapiens had an enormous wanderlust or was the result of convergent evolution. Or it shows God wanted to be sure His goal was met.