What would humanity look like if we had no population bottleneck 70,000 years ago?

General Questions
#1

The exact nature of the population bottleneck is controversial but I think it’s widely accepted that at some point 70,000-100,000 years ago Homo Sapiens came pretty close to extinction. Some estimates put the surviving population as low as 2000 individuals.

It is known we have very low genetic diversity compared to other species. What would the human race look like if we never had that bottleneck? Would perhaps mottled or striped skin patterns commonly exist? Would we have much larger ranges in height and body shape? Or would we look the same and just have a broader range of resistance to nasties?

Anything we can extrapolate from other species which didn’t have such a bottleneck?

#2

Your question is a little flawed because there were at least four different human species that lived more recently than 70,000 years ago. Newer evidence suggests if not proves that Neanderthals never died out completely. Instead, they hybridized with some homo sapien populations in Europe. Most people of European ancestry have a significant contribution of Neanderthal ancestry in their genome (1% - 5%+ percent is common). There was also the Denisovansfound in the area that is now Siberian Russia. Little is known about them except that they were also genetically distinct and possibly interbred with some homo sapien populations as well.

Finally, there is Homo floresiensis which is also a rather recent discovery. Their remains were found on an island on Indonesia and they were called the Hobbit People because they were very short. The researchers that found them were astounded because the remains found were only 9,000 years old but the native islanders were not surprised at all. They firmly claim that they were around in the last few hundred years until they killed them off on purpose.

The point to all of my comments is that modern human evolution is a quickly evolving science and a lot of what you think you know isn’t true. It is most likely true that homo sapiens went through an extreme population bottleneck at one point but that was only one of a few very similar species that also survived and hybridized during that time.

It is a fascinating question in general and new scientific tools can help answer it over time but the true story is still far from complete.

#3

Of course, the real question about the bottleneck is “why”?

Did the group that formed the core of homo sapiens develop some interesting genetic anomaly (conceptual or advanced thinking? Language?) that allowed them to overwhelm any other group? Or was it an ecological or climate event?

#4

We didn’t have a predisposition to this before the bottleneck, judging by other hominids, so it’s highly unlikely.

More than the range between Mbuti and Maasai we currently have?

What do you mean by “the same”? We’re pretty variable in appearance, more so than our nearest living relatives by far.

#5

Timing links it tothis event although there’s lots of dissent.

#6

A better question might be why different populations have different types of diversity. From hair and eye colours in Europe to skin tone in the Med and Middle East to body size in Africa.

#7

Do they, though? Does Europe have any more hair/eye colour diversity than Asia does? And the in-Africa range of skintones is greater than that in the Med, never mind what you find in Asia. Same with height variations - Africa has pygmy peoples, but so does Asia and Oceania.

#8

Ok fair point. Do we have more or less genetic diversity than Chimpanzee’s and Bonobo’s?

#9

Less. Much less. This is covered up somewhat by chimps expressing more-or-less the same phenotypic appearance, compared to people. But the diversity is greater.

#10

Yes, Europe does have greater hair/eye color diversity than anywhere else.

While other places have a range of adult human heights, that range is greatest in Africa.

#11

Name a eye or hair colour that occurs in Europe that *doesn’t *occur in Asia

True, but that wasn’t what AK84 said…the implication was that Asia, for instance, doesn’t have a large height variation, but you could stand a Pashtun next to an Andaman islander and see that variation for yourself. Or stand a Dutch person next to a Maltese.
Similarly, Asians have the same red-blonde-brown-black hair variations, and the same brown-green-blue eye colour variations as Europe. True, there aren’t many natural blonde-haired, blue-eyed Asians running around. But they do exist.

#12

Anatomically modern humans emerged about 200K years ago, and the reason they are called that is that there isn’t much difference, anatomically, between them and us. So, it’s unlikely we would look much different today since we looked pretty much the same before the bottleneck.

#13

We really don’t know that. There is very very little known remains of homo sapiens from 120,000 to 200,000 years ago. Zero complete skeletons, a handful of partially complete skulls and bone fragments apart from that. Theres a huge amount of guesswork and speculation during that period.

#14

Here’s a good article about Homo Sapiens Idaltu and it makes clear exactly how few individuals we have evidence of from that period 80,000-160,000 years ago.
http://www.berkeley.edu/news/media/releases/2003/06/11_idaltu.shtml

I don’t see how theres any way we can have an idea of the variation of appearance and other characteristics in the population from so few samples.

#15

Some of the more striking cosmetic differences could come fromlater mutations, though, not just differential expression of pre-existing genes.

#16

We have a considerable number of fossils of what are often called “archaic” modern humans, and none is particularly far outside the normal range of what we see today. There was an overall robustness in the skeleton, but that is seen across the board.

#17

From what exact time period and how many? cite please?

The article I posted is talking about less than 20 individuals from 80,000 - 160,000 years ago with significant amounts of bones, apart from teeth. Sure we have plenty of teeth, but how much can you tell about appearance just from teeth?

#18

Quite a bit, apparently.

#19

Fossils like these.

Even if you included Neanderthals in our gene pool (which they are, but at very low frequency), we wouldn’t look all that different. Stockier, perhaps with faces that project out a bit more than average. There is nothing in the fossil record, even including pre-sapiens that hints at morphologies widely different from what we see in modern populations today. In your OP you asked about things like “striped skin”. That, compared to what we actually see in the fossil record, would be called “far out in left field”.

Give this guy a shave and a haircut, and you’d hardly give him a second glance if you passed him on the street.