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Another important point here is that genes don't divide infinitely, so that if you go back some distance, you start finding ancestors from whom you actually did

Another important point here is that genes don't divide infinitely, so that if you go back some distance, you start finding ancestors from whom you actually didn't get any DNA. The book Who We Are and How We Got Here talks about this. When DNA recombines at conception, it only snips and stitches in a fairly limited number of places. It doesn't 'mix' finely like paint. It's more like taking two short pamphlets of ~25 pages, cutting each numbered page horizontally at a random vertical point, and then assembling a new pamphlet of the original size from each pair of pages (pamphlet A's page from above the cut, pamphlet B's from below). All this to say that if you go back something like 800 years, you have ancestors from whom you didn't get any genes at all. This means that these infintesimal mixings have even less impact than you'd think. A modern Japanese person could have a European ancestor who traveled to Asia a thousand years ago, but have zero genes from that ancestor. Which means that while that European is technically an 'ancestor', this is just a bit of historical trivia, it means literally nothing about that Japanese person's biology. --- On to the color commentary: I suspect that articles like this are heavily influenced by the politically-based drive to try to minimize intergroup genetic differences in humans. The reality is opposite the title - humans are far more distinct, especially on group levels, than is commonly understood. The notion that single common ancestors (among trillions) mean people from hugely divergent groups are 'related' in some meaningful way is just exploiting and expanding the ignorance of the public around how genetics actually work. It's arguably a pro-social thing to do; I'd say I agree with the philosophy here, but that doesn't make it true and the 'noble lie' seems anything but to me. The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, and Australian Aborigines is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups, in completely different environments. The genetic split between timber wolves and Chihuahuas was like 5,000 years ago and I bet they have common ancestors much more recently than that.

JPLeRouzic 6y ago
>> The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, ... is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups. Any citation?
- simonh 6y ago
  The 'recent dispersal' started some 70-50,00 years ago, reaching Europe about 40,000 years ago. https://en.wikipedia.org/wiki/Early_human_migrations#Homo_sapiens https://en.wikipedia.org/wiki/Early_human_migrations#Homo_sa... Europeans have pretty low levels of sub-saharan genetic markers, with some remnant markets in southern Europe dating to the late Roman era, diminishing substantially as you move north. https://en.wikipedia.org/wiki/African_admixture_in_Europe https://en.wikipedia.org/wiki/African_admixture_in_Europe
  - bsanr2 6y ago
    Low admixture, sure. And similarity of genetypes?
  - etabetapi 6y ago
    This is tautological, sub-saharan genetic markers are found predominantly in sub-saharan populations by definition. Given how humanity has evolved, "european" markers are a subset of the diversity found in subsaharan populations that are overrepresented from founder effects, with very few exceptions. 40,000 years ago sounds like a long time, but it really isn't. You need an amazingly small amount of migration (about one person per generation) to keep a population in sync with each other genetically.
    - simonh 6y ago
      I get your point. I'm somewhat surprised that the person I was responding to seemed to think it would even need a citation, but there you are. >You need an amazingly small amount of migration (about one person per generation) to keep a population in sync with each other genetically. Well it depends on the size of the population, but even then I don't see how this can be the case. One individual only contributes half their genes to each child, so assuming 2 surviving children that's a 25% lost immediately in the next generation. In just a few generations about half the incomer's genes will be lost in this way. The remainder will likely persist, but equally the number of their descendants that have none or very few of their genes will rise to predominate. In a stable population of 1,000 people, one single individual is unlikely to contribute much more than 1/2,000th of the genes in circulation.
ahartmetz 6y ago
I agree with you about the "noble" lies. You wrote something else that I have never seen before and that seems quite interesting: > When DNA recombines at conception, it only snips and stitches in a fairly limited number of places. It doesn't 'mix' finely like paint. I had always assumed that clearly recognizable traits that children inherit from parents are simply based on the large influence of certain small pieces of DNA. Do you know a good text that discusses that?
- Udik 6y ago
  > I had always assumed that clearly recognizable traits that children inherit from parents are simply based on the large influence of certain small pieces of DNA I never understood this position from the logical point of view. Say that you were put in front of two pictures that are entirely covered except for a small visible part each. The two visible parts of the pictures are different. Would you ever assume the parts that you can't see to be identical, or would you assume they differ from each other as much as the visible parts do?
  - jacobush 6y ago
    It's because DNA is not a one-to-one encoding from code to visible expression. Some very small genes have very large visible expression. Some large chunks of DNA have very little.
    - Udik 6y ago
      > Some very small genes have very large visible expression Let me change your italics: Some very small genes have very large visible expression So small parts of the DNA code for changes that we can visually appreciate. This doesn't mean that the rest of the DNA contains no variations, but just that we cannot see them. But it would be wrong to assume that the only parts that are actually different are those which encode for visible characteristics.
- Complexicate 6y ago
  A 2011 study identified 13 DNA variations across 11 different genes that could be used to predict hair color. This seems like a clearly recognizable inherited trait, based on a large influence of certain small pieces of DNA. The abstract mentions eye color as well. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057002/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057002/
rsynnott 6y ago
> The genetic split between timber wolves and Chihuahuas was like 5,000 years ago and I bet they have common ancestors much more recently than that. Well, for a start, this is completely wrong. Dogs diverged from wolves 20-40,000 years ago (lots of ambiguity over where exactly the divergence should be called), but from a now-extinct wolf species. While dogs and wolves _can_ interbreed, it doesn't happen naturally all that often (and when it does, it's pretty much all unidirectional; dog to wolf). Humans don't have the same issue. A chihuahua, of course, is a result of deliberate and extreme forced breeding of a sort that (thankfully) has not really been practiced on humans. The closest parallel might be certain European royal families who had severe genetic diseases and abnormal physiology due to repeated inbreeding, but those were much, much less extreme. Dogs, though, were subject to fairly dramatic artificial selection from the start.
- deleted 6y ago
  [deleted]
golf5 6y ago
Contradicting that narrative is probably a career ender.
bsanr2 6y ago
"This means that these infintesimal mixings have even less impact than you'd think. A modern Japanese person could have a European ancestor who traveled to Asia a thousand years ago, but have zero genes from that ancestor. Which means that while that European is technically an 'ancestor', this is just a bit of historical trivia, it means literally nothing about that Japanese person's biology." It also means that a modern Japanese person has thousands of "Japanese" ancestors from whom they received zero genes. Of course, this is a bit of misdirection, as the genes that one receives are not unique, but drawn from a pool of possible genotypes common to humanity. The matter of how closely we resemble each other is not one purely of ancestry, but of the size of that pool - our overall genetic similarity. From what I gather, it's not an exceptionally large pool. I may not have gotten whatever gene controls the formation of the human prefrontal cortex from the same nth ancestor as you, but I got it all the same. Also, where does dominance play into this, I wonder?
kenjackson 6y ago
> The reality is opposite the title - humans are far more distinct, especially on group levels, than is commonly understood. This really seems to have some huge assumptions in there. What is commonly understood? I don't think there is much common understanding associated with this. Except maybe that we should treat individuals as individuals, rather than make strong distinctions based on group membership, regardless of any underlying distinctions in the groups. At least that's the noble intent -- I don't think any lies are layered on this.

JPLeRouzic 6y ago

>> The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, ... is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups. Any citation?

simonh 6y ago
The 'recent dispersal' started some 70-50,00 years ago, reaching Europe about 40,000 years ago. https://en.wikipedia.org/wiki/Early_human_migrations#Homo_sapiens https://en.wikipedia.org/wiki/Early_human_migrations#Homo_sa... Europeans have pretty low levels of sub-saharan genetic markers, with some remnant markets in southern Europe dating to the late Roman era, diminishing substantially as you move north. https://en.wikipedia.org/wiki/African_admixture_in_Europe https://en.wikipedia.org/wiki/African_admixture_in_Europe
- bsanr2 6y ago
  Low admixture, sure. And similarity of genetypes?
- etabetapi 6y ago
  This is tautological, sub-saharan genetic markers are found predominantly in sub-saharan populations by definition. Given how humanity has evolved, "european" markers are a subset of the diversity found in subsaharan populations that are overrepresented from founder effects, with very few exceptions. 40,000 years ago sounds like a long time, but it really isn't. You need an amazingly small amount of migration (about one person per generation) to keep a population in sync with each other genetically.
  - simonh 6y ago
    I get your point. I'm somewhat surprised that the person I was responding to seemed to think it would even need a citation, but there you are. >You need an amazingly small amount of migration (about one person per generation) to keep a population in sync with each other genetically. Well it depends on the size of the population, but even then I don't see how this can be the case. One individual only contributes half their genes to each child, so assuming 2 surviving children that's a 25% lost immediately in the next generation. In just a few generations about half the incomer's genes will be lost in this way. The remainder will likely persist, but equally the number of their descendants that have none or very few of their genes will rise to predominate. In a stable population of 1,000 people, one single individual is unlikely to contribute much more than 1/2,000th of the genes in circulation.

ahartmetz 6y ago

I agree with you about the "noble" lies. You wrote something else that I have never seen before and that seems quite interesting: > When DNA recombines at conception, it only snips and stitches in a fairly limited number of places. It doesn't 'mix' finely like paint. I had always assumed that clearly recognizable traits that children inherit from parents are simply based on the large influence of certain small pieces of DNA. Do you know a good text that discusses that?

Udik 6y ago
> I had always assumed that clearly recognizable traits that children inherit from parents are simply based on the large influence of certain small pieces of DNA I never understood this position from the logical point of view. Say that you were put in front of two pictures that are entirely covered except for a small visible part each. The two visible parts of the pictures are different. Would you ever assume the parts that you can't see to be identical, or would you assume they differ from each other as much as the visible parts do?
- jacobush 6y ago
  It's because DNA is not a one-to-one encoding from code to visible expression. Some very small genes have very large visible expression. Some large chunks of DNA have very little.
  - Udik 6y ago
    > Some very small genes have very large visible expression Let me change your italics: Some very small genes have very large visible expression So small parts of the DNA code for changes that we can visually appreciate. This doesn't mean that the rest of the DNA contains no variations, but just that we cannot see them. But it would be wrong to assume that the only parts that are actually different are those which encode for visible characteristics.
Complexicate 6y ago
A 2011 study identified 13 DNA variations across 11 different genes that could be used to predict hair color. This seems like a clearly recognizable inherited trait, based on a large influence of certain small pieces of DNA. The abstract mentions eye color as well. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057002/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057002/

rsynnott 6y ago

> The genetic split between timber wolves and Chihuahuas was like 5,000 years ago and I bet they have common ancestors much more recently than that. Well, for a start, this is completely wrong. Dogs diverged from wolves 20-40,000 years ago (lots of ambiguity over where exactly the divergence should be called), but from a now-extinct wolf species. While dogs and wolves _can_ interbreed, it doesn't happen naturally all that often (and when it does, it's pretty much all unidirectional; dog to wolf). Humans don't have the same issue. A chihuahua, of course, is a result of deliberate and extreme forced breeding of a sort that (thankfully) has not really been practiced on humans. The closest parallel might be certain European royal families who had severe genetic diseases and abnormal physiology due to repeated inbreeding, but those were much, much less extreme. Dogs, though, were subject to fairly dramatic artificial selection from the start.

deleted 6y ago
[deleted]

golf5 6y ago

Contradicting that narrative is probably a career ender.

bsanr2 6y ago

"This means that these infintesimal mixings have even less impact than you'd think. A modern Japanese person could have a European ancestor who traveled to Asia a thousand years ago, but have zero genes from that ancestor. Which means that while that European is technically an 'ancestor', this is just a bit of historical trivia, it means literally nothing about that Japanese person's biology." It also means that a modern Japanese person has thousands of "Japanese" ancestors from whom they received zero genes. Of course, this is a bit of misdirection, as the genes that one receives are not unique, but drawn from a pool of possible genotypes common to humanity. The matter of how closely we resemble each other is not one purely of ancestry, but of the size of that pool - our overall genetic similarity. From what I gather, it's not an exceptionally large pool. I may not have gotten whatever gene controls the formation of the human prefrontal cortex from the same nth ancestor as you, but I got it all the same. Also, where does dominance play into this, I wonder?

kenjackson 6y ago

> The reality is opposite the title - humans are far more distinct, especially on group levels, than is commonly understood. This really seems to have some huge assumptions in there. What is commonly understood? I don't think there is much common understanding associated with this. Except maybe that we should treat individuals as individuals, rather than make strong distinctions based on group membership, regardless of any underlying distinctions in the groups. At least that's the noble intent -- I don't think any lies are layered on this.