Chinese Human Fossils Unlike Any Known Species

[nucklehead]

Curnoe has dubbed the new group the Red Deer Cave people ...

[Buggernut]

Your wrong. It looks like the migration out of Africa occured between 125-60,000 years ago. That's more than enough time to produce the diversity you see in modern humans. Look at aboriginal people in north america and how diverse they are when comparing inuit to aboriginals in south america. They are also totally distinct looking from the Asian people they are descended from.

They've only been isolated for just over 10,000 years.

[Buggernut]

A single mutation can change your phenotype pretty quickly, especially in quantitative traits suck as hair colour and skin colour in which pleiotropism may also play a role.

Skin colour variation would have been seriously influenced by natural selection. Homo sapiens who left the sunny equator for more northern regions with less sunlight would have placed a lot of selective pressure towards paler skin to improve vitamin D synthesis and lesser demand for UV protection.

And although humans may appear so different, we are practically 99+% identical. I think because humans are so visually picky may be one driving force for obvious physical differences.

I remember doing a phylogenetic tree last year in university based on a mitochondrial gene, and I found that humans and chimps were more similar than two species of macaque were to each other!

[Hat Trick Maker]

I'm not sure 60,000 years or so could produce that profound a difference.

[Hobble]

Let me see if I have this right. "Races" are separated by 125,000 years or less. "Subspecies" are separated by about 200,000 year or more. Do I have the right idea?

I think that's because the original australoids that lived there have since been displaced by later arriving mongoloids.

[Hobble]

I hear humans and chimps are 98% identical.

[Buggernut]

There are those who argue that "race" doesn't hold any genetic basis at all and only serves as an indicator of physical observable differences.

[taxi]

Let me see if I have this right.  "Races" are separated by 125,000 years or less.  "Subspecies" are separated by about 200,000 year or more.  Do I have the right idea?

I think that's because the original australoids that lived there have since been displaced by later arriving mongoloids.

[Buggernut]

As someone else already said, it really has nothing to do with time. It's more to do with what kind of environmental pressures exist and how isolated a population is. However, in this example, I said that humans left Africa sometime between 125,000-60,000 years ago. That doesn't mean they instantly became isolated populations. Although the neanderthals appeared 600,000 to 350,000, that's not when they became isolated. The common ancestors of humans and neanderthals became isolated from eachother closer to 1 million years ago. So you had probably close to 1 million years of separation between humans and neanderthals ancestors which led to the formation of subspecies. There has never been a group of humans that has remained isolated for anything close to that period of time. Obviously some genes are more commong in certain places in the world (that's why people of European heritage have white skin), however, there has always been genetic flow between humans. It's difficult to cross barriers like the Sahara dessert, so there is some degree of isolatoin, but it was never total. Humans could move up and down the coast.

[Buggernut]

You didn't answer the question.

[taxi]

The Nile Basin seems like a more likely passage way than the coast, since you can't drink nor irrigate with salt water.

Anyways, here's a timeline depicting the evolution of humans. Based on it, one million years of separation between humans and neanderthals seems a bit exaggerated.

So what exactly happened between the times the proto-neanderthals and the proto-caucasoids/mongoloids/australoids respectively left Africa to keep the populations isolated from one another and disrupt the gene flow? Did the Nile dry up or something?