Human Origins challenged again

[Brian G Turner]

A couple of stories in the news this week about Human Origins, both of which connect in different yet interesting ways.

1. Africa

The first is the news that original human populations in Africa would not have been homogeneous - but instead would have undergone cycles of isolation, then mixing, resulting in widespread diversity: Humans evolved in partially isolated populations scattered across Africa

Many had assumed that early human ancestors originated as a single, relatively large ancestral population, and exchanged genes and technologies like stone tools in a more or less random fashion.

[But] ... human populations would have gone through many cycles of isolation—leading to local adaptation and the development of unique material culture and biological makeup—followed by genetic and cultural mixing.

2. China

And while there's still the presumption of early humans migrating out of Africa, the dating for this continues to be challenged. The latest is a study from Chinese artifacts suggesting primitive humans - or an early ancestor - were present over 2 million years ago: Earliest evidence of humans outside Africa

Humans left Africa at many times during their history. Living people outside Africa, for example, trace their origins to an exodus that occurred 60,000 years ago.

But there had been no evidence of occupation by human relatives in Eurasia until the Dmanisi evidence at 1.8 million years ago.

Writing in Nature, palaeoanthropologist John Kappelman, who was not involved with the new study, commented: "The roughly 14,000-kilometre trek from eastern Africa to eastern Asia represents a range expansion of dramatic proportions."

However, what the article doesn't mention is Denisovians, a human species that was more closely related to Neanderthals - but genetically distinct - which is believed to have ranged across south-east Asia: Denisovan - Wikipedia

Denisovians are still a mystery, having only been discovered in 2010, and the scientific community is still struggling to categorize them according to the limited data they have.

Either way, what both studies show is that Human Origins appears increasingly more complex than had been originally assumed.

 

[BAYLOR]

Modern man may have interbred with them, because I seem recall that 4 percent of modern human DNA is Neanderthal?

 

[Onyx]

I had thought the 2 million year old homo erectus-like beings found in China was not assumed to be an ancestor, just an earlier wave of hominids that left Africa before the homo sapiens. My understanding is that such groups also evolved into the forerunner of the Neanderthals and Denisovians somewhere outside of Africa.

Of course, if this group in China is found to be part of the Neanderthal and Denisovian lineage, that would make them part of European and Asian lineage as a small percentage.

As time goes on we may see wave after wave of hominids that wandered off the African continent only to die out on their own, be wiped out by more advanced hominids or absorbed into later populations, little different than the process that sent monkeys and later apes out of Africa.


The finding that human evolution happened in clumps is actually something I find much more comforting than the idea that there is a single couple serving as our ancestral parents.

 

[Brian G Turner]

I had thought the 2 million year old homo erectus-like beings found in China was not assumed to be an ancestor, just an earlier wave of hominids that left Africa before the homo sapiens. My understanding is that such groups also evolved into the forerunner of the Neanderthals and Denisovians somewhere outside of Africa.

You may be right - the news articles I read on this were a little vague on anything other than "hominid tools found".