Wednesday, July 19, 2017

Humans Were Present In Australia 65,000 Years Ago.

A new article at Nature definitively dates evidence of human occupation of Australia to 65,000 years ago.

This has many implications. These include the following:

* It puts a latest possible date on an Out of Africa migration. This tends to disprove the hypothesis that there was an Out of Africa migration that failed ca. 75,000 years BP followed by a second Out of Africa migration that struck, ca. 50,000 years BP, that has been advanced by many. The recent trend has been to attribute all early evidence (such as Altai Neanderthal DNA showing admixture with modern humans ca. 100,000 years BP and archaeological traces in the Levant, the interior of Arabia and South Asia) of modern humans outside of Africa to a stillborn Out of Africa migration.

* It puts a latest possible date on Denisovan admixture with the ancestors of Australian Aboriginal people who, together with Papuans and Negrito populations from the Philippines have significant levels of Denisovan admixture today.

* It tends to make the megafauna extinction that followed the arrival of modern humans in Australia less immediate with as much as a 20,000 year gap between first contact and the extinction of some Australian megafauna species.

* It puts a latest possible date on behavioral modernity in anatomically modern humans. Almost all of the evidence used to put the start of the Upper Paleolithic era at around 50,000 years ago has subsequently been found more like 70,000 years ago.


terryt said...

This all is pretty much what I have been maintaining all along. I had many arguments with Maju on the subject! It has always been obvious that Australian Aborigines arrived on that continent before the full development of the Upper Paleolithic.

Mitchell said...

"It puts a latest possible date on Denisovan admixture."

I don't understand this comment.

You can see some Australian discussion in comments here. :-)

andrew said...

Aboriginal Australians have high levels of Denisovn admixture and were isolated from the rest of the world pretty much from the point they arrived onward. And, there were no hominins in Australia before they arrived. So, admixture with Denisovans had to have occurred by 65,000 years ago.

I suppose that you could read what I said to mean that there was no admixture with Denisovans after 65,000 years ago, as I am implicitly assuming single pulse admixture. But, all that I really meant to say was that the latest possible date at which Denisovan admixture could have started to happen was 65,000 years ago.

Plains Wanderer said...

So what does this imply for ENA? Did East Eurasians already share drift to the exclusion of West Eurasians before 65,000 years ago? Or did the ENA ancestry in Australians arrive much later? With these dates getting pushed further back, I suspect that a significant portion of Aboriginal ancestry arrived in Australia relatively recently.

terryt said...

"So what does this imply for ENA?"

I have long suspected that the first batch of humans to enter Australia came via Siberia, not South Asia. Y-DNA C is particularly interesting in that regard. It forms two branches: C2 in the Far East and C1 more widespread. C1a is northern with C1a1 in Japan and C1a2 in Europe. Presumably C1a at one time was spread across Eurasia north of the Tibetan Plateau. C1b is primarily southern, but again looks to have originated in the east. C1b2 is found in Australia and Wallacea while C1b1 is spread through southern Eurasia (C1b1a1) from Indonesia (C1b1a2) to Saudi Arabia (C1b1a3). Much the same shows up with mt-DNA N. That would place the ENA as the first to Australia and would also explain the high level of Denisovan admixture.

"I suspect that a significant portion of Aboriginal ancestry arrived in Australia relatively recently".

Y-DNA K and mt-DNA M fit that situation. Probably 40,000 years ago though.