4 ms·

What's the argument against the seemingly obvious possibility of instead of it being a bottleneck, it was the result of a dominant group? So for the contemporar

What's the argument against the seemingly obvious possibility of instead of it being a bottleneck, it was the result of a dominant group? So for the contemporary example, something like 8% of Asian men are related to Genghis Khan [1]. And that's in a very recent time frame, and in a world that was already much more spread out than the ones in the distant past. It seems that if there was a group that was particularly dominant (killing competitors, spreading their own genes far and wide), as were their offspring and so on, then it could easily lead to a scenario that would look like a bottleneck due to a surge of a very limited number of individuals taking over a disproportionate dominance of the human gene pool. It seems this would look near identical to a bottleneck, even if it wasn't. [1] - https://en.wikipedia.org/wiki/Family_and_descendants_of_Genghis_Khan#DNA_evidence https://en.wikipedia.org/wiki/Family_and_descendants_of_Geng...

daliusd 3y ago
Killing competitors means competitors are dead. Thus bottleneck. How many competitors that group could have killed? Up to 1000 - maybe, 10000 - that would be very interesting. 2000 is still bottleneck
- somenameforme 3y ago
  Killing was an extremely very poor choice of words on my part, as this certainly doesn't have to involve death. Take South Korea as a contemporary example with their publicized 0.7 fertility rate. That trends towards extinction at an exponential pace. But now imagine there was another group within South Korea that started going the opposite direction and just having massive numbers of children. You could even create an equilibrium level (probably more theoretic than practical at the population levels in modern times, but not necessarily in ancient) where this group's fertility trends up end perfectly balancing against the rest of South Korea's low fertility trends, such that the population doesn't even meaningfully change, or maybe even increases, yet the DNA pool ends up near to 100% controlled by a tiny minority. I'm curious if and how this would look different (from a long distant DNA analysis) from the suggestion that suddenly all of South Korea just mysteriously died and these were the only people left.
  - funnymony 3y ago
    Interesting idea. But this would require no intermixing between groups.
svnt 3y ago
There is a pretty good accounting for polygamy in the genetic history of humans as well. https://www.newscientist.com/article/dn14817-polygamy-left-its-mark-on-the-human-genome/ https://www.newscientist.com/article/dn14817-polygamy-left-i... Mitochondrial DNA, which most people understand to be inherited entirely along the female line, is believed to point back to some single individual female “Eve” 100kya.
- raducu 3y ago
  > Even if most Western men don’t take multiple wives, men tend to father children with more females than females do with males, a practice called “effective polygamy”. Maybe I'm oversensitive to men's issues, but I feel western society is very biased against men, to the point that this bias overrides basic logic. No, "men" cannot father children with more females than females do with males, but SOME (highly successful) men father children with more women whereas MORE men are left childless than women. But God forbid we don't portray ALL men as pigs trying to father children with as many women as possible whereas women are helpless victims to this process.
  - neuronic 3y ago
    > but I feel western society is very biased against men This absolutely has to be a troll post. I am flabbergasted, stunned, lacking words.
    - DharmaPolice 3y ago
      While it sounds extraordinary it's a commonly held view. Not in the sense that men (overall) are structurally oppressed but there are various places where males are disadvantaged. (Note : I am not supporting this notion, just reporting what is a popular view).
      - raducu 3y ago
        Why all the disclaimers? Unless, you know, all the knee-jerk reactions about talking about any mens issue have very serious, negative consequences in the modern world.
jjk166 3y ago
That would look very different genetically from a population bottleneck. There are two factors at play: inheritance and mutation. If you had a large population of genetically similar individuals, you'd expect after a few gereations many parallel lineages each with their own distinct mutations. Imagine everyone starts out with a gene that looks like AAAAAAAA; some lines would wind up with AACAAAAA while others wind up with AAAACAAA. In later generations you might see a gene like GACCATTA which came from that first group, whereas a gene like TTAACACG which came from the second (note the position of the C). Alternatively, if you have a small population, mutations are going to accumulate in series. Perhaps you start out with some AAAAAAAA and some TTTTTTTT variants, in later generations you'd expect to find versions of the gene like AATCAGAT and AAACAGAAT which descend from the first line and TTTCAGTC and TGTCAGTT which descend from the second. The lineages' distinctness is conserved, but they both spent a lot of time developing mutations before they radiated. Time estimates can get a little wonky because we don't really know what the mutation rate was at any given point in the past; we can kind of calibrate by sequencing genes of fossil specimens but there are only so many specimens of sufficient quality, and they only tell us which mutations had already occurred by that point in time. But the sequence of events is much clearer.

daliusd 3y ago

Killing competitors means competitors are dead. Thus bottleneck. How many competitors that group could have killed? Up to 1000 - maybe, 10000 - that would be very interesting. 2000 is still bottleneck

somenameforme 3y ago
Killing was an extremely very poor choice of words on my part, as this certainly doesn't have to involve death. Take South Korea as a contemporary example with their publicized 0.7 fertility rate. That trends towards extinction at an exponential pace. But now imagine there was another group within South Korea that started going the opposite direction and just having massive numbers of children. You could even create an equilibrium level (probably more theoretic than practical at the population levels in modern times, but not necessarily in ancient) where this group's fertility trends up end perfectly balancing against the rest of South Korea's low fertility trends, such that the population doesn't even meaningfully change, or maybe even increases, yet the DNA pool ends up near to 100% controlled by a tiny minority. I'm curious if and how this would look different (from a long distant DNA analysis) from the suggestion that suddenly all of South Korea just mysteriously died and these were the only people left.
- funnymony 3y ago
  Interesting idea. But this would require no intermixing between groups.

svnt 3y ago

There is a pretty good accounting for polygamy in the genetic history of humans as well. https://www.newscientist.com/article/dn14817-polygamy-left-its-mark-on-the-human-genome/ https://www.newscientist.com/article/dn14817-polygamy-left-i... Mitochondrial DNA, which most people understand to be inherited entirely along the female line, is believed to point back to some single individual female “Eve” 100kya.

raducu 3y ago
> Even if most Western men don’t take multiple wives, men tend to father children with more females than females do with males, a practice called “effective polygamy”. Maybe I'm oversensitive to men's issues, but I feel western society is very biased against men, to the point that this bias overrides basic logic. No, "men" cannot father children with more females than females do with males, but SOME (highly successful) men father children with more women whereas MORE men are left childless than women. But God forbid we don't portray ALL men as pigs trying to father children with as many women as possible whereas women are helpless victims to this process.
- neuronic 3y ago
  > but I feel western society is very biased against men This absolutely has to be a troll post. I am flabbergasted, stunned, lacking words.
  - DharmaPolice 3y ago
    While it sounds extraordinary it's a commonly held view. Not in the sense that men (overall) are structurally oppressed but there are various places where males are disadvantaged. (Note : I am not supporting this notion, just reporting what is a popular view).
    - raducu 3y ago
      Why all the disclaimers? Unless, you know, all the knee-jerk reactions about talking about any mens issue have very serious, negative consequences in the modern world.

jjk166 3y ago

That would look very different genetically from a population bottleneck. There are two factors at play: inheritance and mutation. If you had a large population of genetically similar individuals, you'd expect after a few gereations many parallel lineages each with their own distinct mutations. Imagine everyone starts out with a gene that looks like AAAAAAAA; some lines would wind up with AACAAAAA while others wind up with AAAACAAA. In later generations you might see a gene like GACCATTA which came from that first group, whereas a gene like TTAACACG which came from the second (note the position of the C). Alternatively, if you have a small population, mutations are going to accumulate in series. Perhaps you start out with some AAAAAAAA and some TTTTTTTT variants, in later generations you'd expect to find versions of the gene like AATCAGAT and AAACAGAAT which descend from the first line and TTTCAGTC and TGTCAGTT which descend from the second. The lineages' distinctness is conserved, but they both spent a lot of time developing mutations before they radiated. Time estimates can get a little wonky because we don't really know what the mutation rate was at any given point in the past; we can kind of calibrate by sequencing genes of fossil specimens but there are only so many specimens of sufficient quality, and they only tell us which mutations had already occurred by that point in time. But the sequence of events is much clearer.