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Humans originated in africa, and only a subset of our species genetic diversity ever left africa. So all immigration from "many places" still represents only a

Humans originated in africa, and only a subset of our species genetic diversity ever left africa. So all immigration from "many places" still represents only a subset of the existing diversity. There is also some immigration directly from africa, but that can only increase it to at most the same as exists there. Almost certainly somewhat less, in practice.

roughly 3y ago
Interestingly, even within Africa, the human genome notably lacks variability, to a point where it’s hypothesized that there was a fairly severe population bottleneck at some time in the last couple hundred thousand years.
- myhf 3y ago
  oh gee i wonder what that bottleneck could have been cough mysterious 1:4:9 monolith cough
  - rbanffy 3y ago
    I don’t remember exactly where I read that, but from mitochondrial DNA it was calculated that at some point we were down to 50 or so individuals.
INTPenis 3y ago
Thank you for the clear explanation. I've heard that humans were at some point reduced to a very small number, like thousands of individuals. So how did a few thousand individuals become such great genetic diversity? Does genetic diversity come from being isolated, instead of mingling with other migratory groups?
- neonnoodle 3y ago
  Human genetic diversity on the whole is very, VERY low compared to other species. The superficial physical variation we associate with ethnic diversity (skin tone, nose shape, lip shape, hair color/texture, eye folds and angles) are genetically insignificant compared to their visual impact.
livinginfear 3y ago
It's worth noting that this is not the only hypothesis for the origin of modern humans: https://en.wikipedia.org/wiki/Multiregional_origin_of_modern_humans https://en.wikipedia.org/wiki/Multiregional_origin_of_modern...
- astrange 3y ago
  It's the only correct one though. There is small amounts of "multiregionality" since some peoples are part Denisovan and most everyone is part Neanderthal, but it's not even a plurality in anyone we've ever found.

roughly 3y ago

Interestingly, even within Africa, the human genome notably lacks variability, to a point where it’s hypothesized that there was a fairly severe population bottleneck at some time in the last couple hundred thousand years.

myhf 3y ago
oh gee i wonder what that bottleneck could have been cough mysterious 1:4:9 monolith cough
- rbanffy 3y ago
  I don’t remember exactly where I read that, but from mitochondrial DNA it was calculated that at some point we were down to 50 or so individuals.

INTPenis 3y ago

Thank you for the clear explanation. I've heard that humans were at some point reduced to a very small number, like thousands of individuals. So how did a few thousand individuals become such great genetic diversity? Does genetic diversity come from being isolated, instead of mingling with other migratory groups?

neonnoodle 3y ago
Human genetic diversity on the whole is very, VERY low compared to other species. The superficial physical variation we associate with ethnic diversity (skin tone, nose shape, lip shape, hair color/texture, eye folds and angles) are genetically insignificant compared to their visual impact.

livinginfear 3y ago

It's worth noting that this is not the only hypothesis for the origin of modern humans: https://en.wikipedia.org/wiki/Multiregional_origin_of_modern_humans https://en.wikipedia.org/wiki/Multiregional_origin_of_modern...

astrange 3y ago
It's the only correct one though. There is small amounts of "multiregionality" since some peoples are part Denisovan and most everyone is part Neanderthal, but it's not even a plurality in anyone we've ever found.