6 ms·

DNA extracted from ancient African skeleton shows mixing with Eurasians

39 points by okfine 11y ago

themgt 11y ago
More support for the "Out of Arabia" scenario [1], the implications of which are enormous and potentially awkward. [1] http://dienekes.blogspot.com/2015/08/rethinking-dispersal-of-homo-sapiens.html http://dienekes.blogspot.com/2015/08/rethinking-dispersal-of...
- meric 11y ago
  How so could it be awkward?
  - realquick81 11y ago
    It would mean whites and blacks have difference ancestors.
  - kailuowang 11y ago
    Would like to ask that as well.
  - themgt 11y ago
    (as a layman) The original Out of Africa hypothesis had the "happy conclusion" that anatomically modern humans (AMH) evolved in a small group within Africa and then migrated out to populate the rest of the world, displacing (and not interbreeding with) older hominids. And everyone on earth is a descendent of that small first group, so we're all one coherent happy family. The evolving picture today appears much more likely that some not-quite AMHs migrated from Africa to Arabia where they lived alongside and interbred with already-present Neanderthal culture, became anatomically modern and developed Upper Paleolithic tools/culture (which were perhaps actually an evolution of Neanderthal culture), spent a while fairly isolated and evolving in Arabia, and eventually as AMHs migrated out to displace/interbreed with the planet's other hominids. So, awkward because it's a much more complex, convoluted story, with a lot more space for different populations of humans to have significant genetic differences. You're also left with Africa potentially having a population of pre-AMH homo sapiens and other hominids, with only quite recent back-migration admixing in "modern human" DNA.
    - JoeAltmaier 11y ago
      Is it fair to say that anatomically modern humans happened after leaving Africa? Sure some more changes happened; change continued in Africa as well. And the Neanderthal 2-6% is probably not that significant. Another interpretation is, moving to Northern climates with reduced sunlight resulted in decreased melanin (to ensure sufficient vitamin D) which allowed more ultraviolet damage thus increased mutations (blue eyes, red hair and so on). In this view, Africa retains 'modern human anatomy'; the rest of the world is a sort of Galapagos Bird situation.
      - dmm 11y ago
        I don't understand percentages used to describe genetic similarity. I mean I heard that humans share 50% with bananas and 96% with chimpanzees. So if 4% is the difference between humans and chimps then 2-6% can be very significant, right? Or can those numbers even be compared?
        JoeAltmaier 11y ago
        Yeah. Don't know. Maybe its "of the genes that vary"?
        dogma1138 11y ago
        The percentage difference is calculated using a very odd system which ignores all the actual differences. For example if Humans and Bananas each have 5000 coding genes in common the difference will be measured only on those genes we actually share (out of 20-25K coding genes in humans, no clue how many coding genes do bananas have), so the difference is actually much greater than the 50%, 4%, 1% or what ever figure you get because the big differences are simply discarded. These days there's a cartoon for everything :) https://www.youtube.com/watch?v=IbY122CSC5w https://www.youtube.com/watch?v=IbY122CSC5w And this is without even going into gene expression and epigentics which play a role which some might even consider to be bigger than what actual genetic data you might happen to carry along with you. Heck chickens still have the genes to grow teeth and feathered scales like the dinosaurs they've evolved from however these genes are not expressed anymore in nature.

39 points by okfine 11y ago

More support for the "Out of Arabia" scenario [1], the implications of which are enormous and potentially awkward. [1] http://dienekes.blogspot.com/2015/08/rethinking-dispersal-of-homo-sapiens.html http://dienekes.blogspot.com/2015/08/rethinking-dispersal-of...

meric 11y ago
How so could it be awkward?
- realquick81 11y ago
  It would mean whites and blacks have difference ancestors.
- kailuowang 11y ago
  Would like to ask that as well.
- themgt 11y ago
  (as a layman) The original Out of Africa hypothesis had the "happy conclusion" that anatomically modern humans (AMH) evolved in a small group within Africa and then migrated out to populate the rest of the world, displacing (and not interbreeding with) older hominids. And everyone on earth is a descendent of that small first group, so we're all one coherent happy family. The evolving picture today appears much more likely that some not-quite AMHs migrated from Africa to Arabia where they lived alongside and interbred with already-present Neanderthal culture, became anatomically modern and developed Upper Paleolithic tools/culture (which were perhaps actually an evolution of Neanderthal culture), spent a while fairly isolated and evolving in Arabia, and eventually as AMHs migrated out to displace/interbreed with the planet's other hominids. So, awkward because it's a much more complex, convoluted story, with a lot more space for different populations of humans to have significant genetic differences. You're also left with Africa potentially having a population of pre-AMH homo sapiens and other hominids, with only quite recent back-migration admixing in "modern human" DNA.
  - JoeAltmaier 11y ago
    Is it fair to say that anatomically modern humans happened after leaving Africa? Sure some more changes happened; change continued in Africa as well. And the Neanderthal 2-6% is probably not that significant. Another interpretation is, moving to Northern climates with reduced sunlight resulted in decreased melanin (to ensure sufficient vitamin D) which allowed more ultraviolet damage thus increased mutations (blue eyes, red hair and so on). In this view, Africa retains 'modern human anatomy'; the rest of the world is a sort of Galapagos Bird situation.
    - dmm 11y ago
      I don't understand percentages used to describe genetic similarity. I mean I heard that humans share 50% with bananas and 96% with chimpanzees. So if 4% is the difference between humans and chimps then 2-6% can be very significant, right? Or can those numbers even be compared?
      - JoeAltmaier 11y ago
        Yeah. Don't know. Maybe its "of the genes that vary"?
      - dogma1138 11y ago
        The percentage difference is calculated using a very odd system which ignores all the actual differences. For example if Humans and Bananas each have 5000 coding genes in common the difference will be measured only on those genes we actually share (out of 20-25K coding genes in humans, no clue how many coding genes do bananas have), so the difference is actually much greater than the 50%, 4%, 1% or what ever figure you get because the big differences are simply discarded. These days there's a cartoon for everything :) https://www.youtube.com/watch?v=IbY122CSC5w https://www.youtube.com/watch?v=IbY122CSC5w And this is without even going into gene expression and epigentics which play a role which some might even consider to be bigger than what actual genetic data you might happen to carry along with you. Heck chickens still have the genes to grow teeth and feathered scales like the dinosaurs they've evolved from however these genes are not expressed anymore in nature.