„10 Punkte, die man über die menschliche Evolution wissen sollte“

Razib Khan führt „10 Punkte über die menschliche Evolution an, die man man wissen sollte“:

1. The expansion/development of modern humans occurred within Africa for tens of thousands of before their expansion „Out of Africa.“ Most of the ancestors of non-African humanity seem to have started expanding rapidly from a small founder group of 100-1,000 50-75 thousand years years ago.

African humanity has a different and more complex historical pattern, with lineages which began diverging as early as 200,000 years before the present, and then mixing back with each other.

2) Related to #1, we’re one species, so rather than an expanding „tree“ from common ancestors, it’s better to think of a mesh which keeps coming back together, as some branches are pruned, and the whole pulses out periodically.
All major human populations seem to be the product of relatively recent fusions between diverged branches.
Africa was the source of modern humanity, but clearly there has been „back migration“ from Eurasia.

3) Many of the phenotypes we define as characteristic of various human populations are relatively recent.
E.g., the depigmented look of Northern Europeans, or the thick straight hair of East Asians.

4) The Denisovan version of EPAS1 which is found in Tibetans illustrates a general trend: we have adaptations from other very diverged human lineages through low levels of gene flow[2].

5) The transition to agriculture and complex „civilization“ seems correlated to pulses of highly fecund male paternal lineages.
Many of the common Y chromosomes today exhibit a pattern of diversification indicative of explosive population growth.

6) It seems unlike there is one singular genetic change which makes us sui generis or distinctive in relation to our hominin cousins.
This is less certain than 1-5, but I’m pretty sure that this is so.
Researchers have been looking for years, and not finding anything definitive, and I think there’s a reason.
There isn’t anything definitive.
Many genetic changes come together to make our lineage distinctive.

7) A lot of adaptation occurs through reemergence of old variation which is floating around in the human population.
For example, the lightening of skin across parts of Eurasia co-opt common mammalian pigmentation pathways.

8) Cultural flexibility does not negate biological evolution.
On the contrary, strong shifts in cultural norms seem to drive biology.
Lactase persistence is a clear case, but even something like malaria adaptation is ultimately due to anthropogenic environmental changes.

9) We are all equally descended from common ancestors.
There are no „most ancient“ human lineages.
We’re all equally recent by definition.

10) There are evolutionary genetic events in our history which are hinted at in the most recent data, so there are major lacunae in our knowledge.
The picture is well formed, but not complete.
E.g., there is evidence of pulses out of Africa ~100,000 years ago into Eurasia in both genetic and fossil data.
These lineages may have gone extinct, or, their contribution may be difficult to detect with current data sets.
But there is clearly more to be told in this story.

7 Gedanken zu “„10 Punkte, die man über die menschliche Evolution wissen sollte“

  1. „9) We are all equally descended from common ancestors.
    There are no „most ancient“ human lineages.
    We’re all equally recent by definition.“

    Kann man nicht sagen, dass die „ältesten“ Populationen/Abstammungslinien diejenigen sind, welche den Ur-Homo sapiens genetisch am ähnlichsten sind? Ist ja nicht so, dass die Evolution überall für die gleichen/gleich viele Änderungen gesorgt hätte.

  2. Die Mutation erfolgte mit dem Denkvermögen, dem abstrakten. Das ist ein menschliches Alleinstellungsmerkmal. Es wäre natürlich naiv anzunehmen, dies wäre durch eine Punktmutation entstanden, aber es ist schwer in den Unterschieden zu Affen auszumachen. Niemand hat eine konkrete Idee, wonach man überhaupt suchen müsste.
    Irgendwann wird die Menschheit das wissen 🙂
    Nur die Naturwissenschaft macht das möglich.

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