Adaptive Neanderthal admixture

Finally, there are papers  out on the long-term consequences of Neanderthal admixture – one by Sriram Sankararaman in Nature, the other by Benjamin Vernot in Science.

The general picture is that anatomically modern humans exiting Africa mixed, to a degree,  with Neanderthals. Some of the Neanderthal alleles were neutral, some were disadvantageous in modern humans and were lost fairly rapidly, and a few had favorable fitness consequences and have become common.  All that was highly likely a priori. I would say it was obvious, if that word meant anything.  It should have been the default assumption from 1927 on, after Haldane calculated the probability of success for a single copy of an advantageous allele.  Wasn’t, though.

Exactly which kinds of Neanderthal alleles would give advantage was less obvious.  I suspected that Neanderthals would be resistant to local pathogens, and that such genetic defenses could easily pay off in modern humans moving into Eurasia.  It looks as if some of that happened – there is a good chance that some common HLA alleles in Eurasians originated in Neanderthals, and some Neanderthal variants involved with defense against viruses have become common.

I thought that anatomically modern humans might have picked up alleles that dealt better with the big swings in day length characteristic of northern latitudes.  In an earlier talk, Sakararaman  mentioned a common Neanderthal version of the CLOCK gene in Europeans, but that doesn’t show up in the paper, so maybe that turned out to be a mistake.

It looks as if both Europeans and East Asians have picked up Neanderthal versions of  several keratin filament genes, involved in hair and skin formation.  Not fixed, but pretty common.  This might have something to do with the non-kinky hair found in most Eurasians.

Some of these common Neanderthal alleles may have some effect on the central nervous system, but as usual, we have such a poor understanding of gene function that it’s hard to tell. A Neanderthal variant of TANC1 is common in Europeans, and that gene is thought to regulate dendritic spines and excitatory synapses.  Looking at the broader question, an unusual number of selected Neanderthal alleles were found that are associated with major depression. So maybe those alleles affected mood regulation. Perhaps depression is part of a strategy for dealing with long winters.

There are gene deserts in which you find very few Neanderthal alleles, presumably because those alleles didn’t work well in modern humans. There is a dearth of testes-associated gene,  not too surprising because they evolve particularly rapidly and are therefore more likely than average to be incompatible with a sister group that diverged some time ago.  The area around FOXP2 is such a desert:  Neanderthals were perhaps worse at speech, or any rate different in some way that didn’t mesh.

There are some signs of reproductive incompatibility with modern humans, but obviously not enough to prevent adaptive introgression. David Reich suggests that Neanderthals were “at the very edge of being biologically incompatible”.  I doubt that, for two reasons.  First, the known cases of species intersterility in primates all took longer to develop. Bonobos and chimps manage, and they’ve been separated something like 800,000 years. In addition, there is evidence that African hunter-gatherers (Bushmen and Pygmies)  picked up some genetic material from an unknown archaic group, one that split off considerably earlier than Neanderthals, something like 900,000 years.

Some Neanderthal haplotypes are risk alleles for various diseases. Chris Stringer said “Studies have also already been published which show that humans outside of Africa are more vulnerable to Type 2 Diabetes, and that is because we bred with Neanderthals, while those who stayed inside Africa didn’t.”  Of course that is not actually true. In the US, blacks have Type 2 diabetes rates that are about twice as high as whites.  Pima Indians have incredibly high rates, but they have almost exactly the same amount of Neanderthal ancestry as Europeans.   I would bet that the selective environment of the past few thousand years matters more than Neanderthal ancestry, or the lack of it.  That said, Neanderthal alleles can play a role in that selective process.

In our book, we suggested that the big bang of the Upper Paleolithic,  the dramatic increase in cultural complexity seen in Europe some 40,000 years ago, might have been triggered, at least in part, by an influx of adaptive Neanderthal alleles. Right now, from the evidence in these papers, I’m not seeing a strong case for that. Of course we only understand what half these genes are doing,  so the fat lady hasn’t finished singing, but  we may well be wrong.  Of course that dramatic increase in cultural complexity did happen, and for that matter, it is still true that average IQ scores are quite low in sub-Saharan Africa and its diaspora.  But IQ scores are also low in populations such as Australian Aborigines that have about the same amount of Neanderthal admixture as other people outside of Africa – so at minimum the story is  more complicated.

 

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95 Responses to Adaptive Neanderthal admixture

  1. Steve Sailer says:

    So, depression is good for sitting around the family cave all winter without getting too antsy and driving your loved ones crazy?

    • Tom says:

      Perhaps it’s associated with being less impulsive, more reflective, etc. You feel less like partying, so maybe you’re less likely to blow the reserve of meat that’s needed to last all winter in a giant feast.

      • Steve Sailer says:

        Indeed.

        I’ve always wondered about the dry seasons that are common in the tropics. Would they have similar fitness effects as winters in the north, or are they fundamentally different?

      • Sandgroper says:

        Steve: Dry tropics or humid tropics? If you live at the equator, there are no seasons.

        I live on the Tropic of Cancer – summers are wet, but getting enough UV exposure is not a problem because the sun is almost directly overhead. Winters are dry and sunny, so no problem still getting enough UV exposure.

        Same in northern Australia, although they are ‘dry tropics’ – they have a wet season (‘summer’) and a dry season (‘winter’) which is less hot but still hot, and sunny.

        At the equator, all days are of equal length (by ‘day’ I mean the time between sunrise and sunset). On the tropics, days in winter are shorter than days in summer, but the difference is a lot less than at much higher latitudes.

        People in the tropics don’t suffer from the seasonally induced depression that, say, Scandinavian and Russian people may be prone to – I suppose hence the noticeably lower per capita vodka consumption.

      • Sideways says:

        Overeating is a common symptom of depression.

      • citygray says:

        Not true Tom. I scored very low even though I’m African American 0.8 to be exact. I come from a family with a very high degree of admixture from the Blue Ridge Mountains, but on most Neand. friendly branches testable, I missed those donors. Grandmother(mother’s mother) tested at 2.0, and her father came from a N.A. and European background. Her mother on the other hand I’m pretty sure had not a thimble of admixture. Same thing happened on my father’s side. I always wondered how I could come out darker than my parents.

        My point is though that I’m probably the most conservative out of all my higher scoring relatives. I’m the one they come to for money when they squander the mortgage. An anomaly ? Maybe, but I think that it has more to do with culture and ideology when it comes to such things. Thrifty individuals tend to share that trait first and foremost or at least from my perspective which is pretty much constantly. Old Black women tend to squirrel away like no tomorrow and have no ACCULTURATION for bling bling other than to splurge on the occasional Sunday hat. I can understand why one might get that though so I’m not taking offense. Considering all of the high profile ignorance that the media and entertainment industry pay homage to, I might be inclined to believe so myself. I do worry where the culture is headed with such a stand out subculture seemingly leading it.

    • Sandgroper says:

      I’m not being (totally) flippant. Seasonally induced depression may have an adaptive advantage at high latitude where you can just shut down, crawl into a corner of the cave or whatever and sleep through the long cold winter nights, reducing your energy needs to a minimum.

      Modern societies don’t let people do that too much, so it seems like some people develop ‘coping’ strategies – guzzling vodka, scoffing pounds of chocolate or whatever. My buddy in Seattle tells me that coffee consumption is so high there because it never stops raining.

      English people living in the tropical colonies used to be noted for their gin and tonic consumption, but that was more to do with the heat being intolerable and the natives revolting, and the tonic contains quinine, which is obviously protective against malaria.

  2. dave chamberlin says:

    I respect your careful scientific approach, no conclusions drawn without proof. But I cannot find any other plausible reason for the enormous advantage given a small population (I am referring to the human bottleneck of approximately 70,000 years ago) or the poorly named “great leap forward” of 40,000 years ago other than the influx of advantageous alleles from neanderthals. Prior to proof that we are a small percentage neanderthal the prevailing theory for the bottleneck was we almost went extinct because of a super volcano and that the “great leap forward” was because of an incredibly advantageous mutation. Neither of these explanations ever passed the smell test with me. I fully understand your scientific approach that there is no strong case from the evidence yet, but I would give really good odds that admixture of anatomically modern man with neanderthals and the influx of their genes caused us to move from modern in appearance to NEARLY modern in inventiveness.

    This may seem to contradict Greg’s statement “I would bet that I would bet that the selective environment of the last few thousand years matters more than Neanderthal ancestry, or lack of it,” but it doesn’t. Evolution is on going and as John Hawks and Greg Cochran have pointed out to me accelerating because bigger populations cause more favorable mutations. I need to add that I’m just a dabbling diletante, not a serious scientist like Cochran or Harpending, so what do I know. Why the bottleneck occurred 70,000 years ago, the “great leap forward” 40,000 years ago, the agricultural revolution 10,000 years ago and the industrial revolution just 170 years ago gives support to the idea we are still a work in progress.

    • Sandgroper says:

      There’s a problem with looking at this in a eurocentric manner, given that all groups outside of sub-Saharan Africa got it, mostly before population divergence, and that East Asians got more of it (whatever it was) in a second pulse. Intuitively, it would seem more likely you could figure out what the adaptive advantages might have been if you look at all of the groups that got whatever it was.

      I’m kind of curious to know whether the EDAR gene variant carried by East Asians was derived from the second pulse they got, but I don’t have access to the full papers. And in which case, what the adaptive advantage that came with it actually was.

      • dave chamberlin says:

        When it comes to admixture of hominids from various continents the world becomes middle eastern centric. After all that is where the continents of Africa, Europe, and Asia join. And indeed that is where a small population of anatomically modern men and Neanderthals started their expansion to the rest of the world.

    • little spoon says:

      The Neandethals were out of africa for several hundred thousand years and they never made a great leap forward. The archeological evidence suggests that from day one when homo sapiens sapiens stepped out of Africa, we were at least on par with Neanderthals technologically. So, if we leaped forward because of genes from them, those same genes weren’t working for them in the way that they worked for us.

      Homo sapiens sapiens was out of africa for 60K years and we got to space exploration and smartphones. Neanderthals were out of africa for 10 times as long and they never got to a written language.

      I agree with agnostic below. If we owe anything to Neanderthals, it might be that they were real competition in a way that all the other significantly dumber animals weren’t. IQ 70 could hunt a mastodon. But IQ 70 needed to get a mental edge to beat a fellow hominid on his native turf.

      • gcochran9 says:

        I guess I will explain it again. Imagine a Russian T-34 tank, circa 1942. It was a good tank, in many ways better than any German tank [sloped armor, diesel engine, Christie suspension, wide tracks], but not better than German tanks in every way. For example, the T-34 had low mechanical reliability, low-quality optics, few Russian tanks had radios, and its two-man turret crew was inferior to the German three-man turret crews (commander, gunner, and loader)

        If you had taken the best features of the T-34 and the PZ-IV, you would have had a tank that was better than either.

        Hybridization allows for similar effects in nature. Even if Neanderthals were competitively inferior to anatomically modern humans, it is likely that they would have some strong points – at bare minimum, adaptation to local climate and disease. So, after some natural selection to throw out the Neanderthal alleles that didn’t work and magnify those that did, people could have ended up with the strengths of both populations.
        In principle, this is a way of acquiring a whole bunch of advantageous alleles very rapidly.

        Could this have given homo sap a boost in the qualities we are most interested in – personality and cognition? It could have, but we don’t have genetic evidence that it did.

      • TWS says:

        So I’m the bastard child of a T-34 and a German Tiger tank? Hell yeah!

      • little spoon says:

        “Could this have given homo sap a boost in the qualities we are most interested in – personality and cognition? It could have, but we don’t have genetic evidence that it did.”

        Generally, for cognitive traits, it seems like after one generation of interracial mixing, the average offspring is in the middle of the two groups. They may have gifts that tend to be prominent in either group, but they tend not to look vastly more advanced after one generation of mixing. Like you could be half black and half Japanese and have excellent spatial reasoning and great rhythm, but I would not expect a rare physics genius to emerge from that mix.

        In the case of Jews, we see being a mix of european and semetic leads to an intelligence and penchant for intellectual creativity that is on average greater than the average of either of those groups. Technically, in that case, both European and Semetic genes are contributing and essential to Ashkenazi Jews being smart the way they are now. But still, I would not call that mix a show of hybridization vigor, which to me implies that like an animal, the pure mixing of two different groups immediately leads to a stronger offspring. In the case of the Jews, a cultural context where Jews went through XYZ cultural selection pressures in recent history gradually fostered their greater intelligence. For Neanderthals-human mixes, in so much as Neanderthal genes contribute to a great leap forward, I would think that it is not because of pure hybridization vigor because whenever I see two human races mix, the offspring don’t seem to be immediately more intellectually advanced than the parent groups and are instead in the middle of their parents with a few niche talents here and there. I would guess that Neanderthal genes contribute to human intellectual creativity the way Semetic genes contributed to Jewish intelligence. The semetic genes are essential, but the cultural context and self concept of Jews over centuries is what encouraged the emergence of greater intellectual capacity than either of the founder groups.

      • gcochran9 says:

        You’re not getting the point. Hybrid vigor is a first-generation effect – that’s not what I’m talking about.

      • Sideways says:

        LS: suppose one group has giant brains and another has compact, efficient brains. They interbreed and the resulting people have large brains with some of the power per cc advantage of the smaller brained group. The traits aren’t on the same genes, so they could wind up having both.

      • little spoon says:

        “You’re not getting the point. Hybrid vigor is a first-generation effect – that’s not what I’m talking about.”

        My original statement was not that hybridization with an “inferior” group cannot lead to offspring that is better than either group. My original statement was the following-

        “So, if we leaped forward because of genes from them, those same genes weren’t working for them in the way that they worked for us. ”

        I am not claiming that the genes do something different in homo sapiens sapiens, just that their contribution produces a different overall effect. I believe that is what you are trying to tell me? Or no?

        But that is not my point. What I am trying to convey is the following- If you asked why European Jews are smart, the best answer would be that it was because they did cognitively demanding professions for a long period which favored intelligence (assuming that is true). You could also answer that the combination of genes from Semetic and European ethnicities allows for a bump in intelligence. That is a true answer, but I don’t think it’s the best answer. I think the best answer is the historical cultural explanation. I think Neanderthal human mixes may be similar. Technically, Neanderthal genes might have contributed to a leap in intellectual capacity, but saying that we received an influx of Neanderthal genes is not the best answer for why we advanced suddenly. Much like how saying Jews received an influx of European genes is not really a great answer for why Ashkenazi Jews became smarter.

        I agree with your statement-

        “I would bet that I would bet that the selective environment of the last few thousand years matters more than Neanderthal ancestry, or lack of it,”

      • gcochran9 says:

        Selection is limited by available genetic variation, so a lot depends on how much genetic variation is available. That is related to population size. Back in the days of old, human population sizes were small, and even if a particular mutation would have had a very positive effect, it still could take hundreds of thousands of years (on average) for that mutation to occur, become established, and rise to high frequency. Thus it was entirely possible that Neanderthals could have something valuable that anatomically modern humans didn’t…

        One reason that picking up a bunch of alleles from a closely related species isn’t a good explanation for the recent development of high Jewish intelligence is that we know it didn’t happen. On the other hand, it did happen 50,000 years ago, so it is a possible partial explanation for an apparent increase in cultural complexity around that time.

        And I give up.

      • little spoon says:

        “One reason that picking up a bunch of alleles from a closely related species isn’t a good explanation for the recent development of high Jewish intelligence is that we know it didn’t happen.”

        Srsly? It’s an analogy. No one sane would ever hypothesize that Jews picked up additional genes from a different specie in recent history. What I said was that Middle Eastern Jews picked up genes from a different sub race (Europeans). But merely saying that they picked those genes up isn’t by itself a complete explanation for why they got smarter.

        “Thus it was entirely possible that Neanderthals could have something valuable that anatomically modern humans didn’t… ”

        Where I said that it was impossible or even unlikely that Neanderthals had something valuable that humans didn’t is a mystery to me.

      • Dr. Gochran, could you please explain the phenomena of “regression to the mean” and “hybrid vigor”? Or refer us to a good source? Ideally one that shows the math?

      • melendwyr says:

        I think Dr. Cochran has better things to do than explain basic concepts which are adequately discussed in practically every textbook on the topic… or, for that matter, Wikipedia.
        If you want to be educated, take responsibility for it. Don’t expect other people to go over the basics for your benefit.

      • Sandgroper says:

        Regression to the mean is why, if you are a rich successful guy because you are smart, it’s a really bad idea to get a ‘trophy wife’ who looks like a million bucks but is as dumb as a brick.

      • gcochran9 says:

        In my salad days, most of the girls I was interested in were very smart. Doesn’t seem that this preference is terribly common.

      • Sandgroper says:

        My idea of the ‘perfect woman’ was blonde hair and big blue eyes, right up to the minute I bumped into a smart, capable, serious and responsible Chinese girl wearing thick spectacles, and made the mistake of actually talking to her. I didn’t notice any of my peer group having a similarly lucky accident.

      • Sandgroper says:

        Razib’s take on this is that you need a close match on the ‘big issues’. That accords with my experience.

  3. JayMan says:

    “Looking at the broader question, an unusual number of selected Neanderthal alleles were found that are associated with major depression. So maybe those alleles affected mood regulation. Perhaps depression is part of a strategy for dealing with long winters.”

    One would then imagine that the global distribution of depression would follow latitude. Anecdotally, that seems to be case. Finding any data on worldwide prevalence is tricky because diagnosis is likely to be highly unreliable and quite variable from one country to the next.

    Here are the reported suicide rates around the world.

    And here are unipolar depressive disorders worldwide. One can tease our a cold-weather connection, but not a definitive one.

    As for Arctic peoples, suicide does appear quite prevalent in the Inuit, but not so much so in the Sami, and I so far haven’t been able to dig up much on Siberian peoples.

    • IC says:

      Suicide rate is a good indication. But there are also correlation between suicide rate and IQ and latitude.

    • Sandgroper says:

      A problem with those maps is that they show national data, which is not too informative for countries which span a wide range of latitudes. I’m sure I’ve seen some more convincing data somewhere on seasonally induced depression at high latitudes – at least to the extent that in some countries it is noted as a problem, and in other countries the subject just never comes up. Stating the blindingly obvious, seasonally induced depression doesn’t get discussed in places so close to the equator that they don’t have seasons.

    • Gottlieb says:

      So, i have this genes but i’m a happy boy!!!
      Well, depression related with introvertion. We should to see what psychological or behavior traits of the subsaharians, us do not have or the inverse.
      The majority of subsaharians and derivatives are very extrovert, asians are very introvert, well, some ”pseudo-causation” here.

      • Gottlieb says:

        http://commons.wikimedia.org/wiki/File:Unipolar_depressive_disorders_world_map_-_DALY_-_WHO2004.svg

        Well, brazilian people are one of the people that make more self-diagnostics around the world. Is verbal-epidemic to say ”i’m depressive”, but in reality, is only the exaggeration of one common emotional state. The majority of brazilians seems happy so much. When you are recurrently extrovert or ”happy” and for some reason, become less happy or extrovert could happen this cause great impression to individual and he make bad use of this sensation how exaggerated the self diagnosis.
        Other possible explanation could be many ”environment” causes like ”extremely competition” in a inequal savage-capitalistic society or biological causes like ”exogamic” depression, people with ”strange” appearance and/or extreme behavior. But, in my opinion, the real unipolar depression which can cause suicide, generally happen in a bio-suscetible people even like good looking like some old actors.

      • Gottlieb says:

        I was seeing the (unfortunately only the summary) job of Arnold Ludwig ” http://www.amazon.com/The-Price-Greatness-Creativity-Controversy/dp/0898628393
        In a study of mixed race in american teens, find that the mixed-teens tend to have more behavior problems than asians and whites but not than blacks.
        The neanderthal could behave more like asians-and-some slavs today and the homo sapiens could be less ”behavior-selection R” like modern subsaharians (because this people have archaic introgression) but also less ” behavior-selection K” than neanderthal. Creative people (and specially genius) tend to have ”complex” personalities, combined creativity and high-risk behavior with hard working and perseverance. In theory, seems two different type of human personalities in internal conflict. Genius and creativity could be the result of hybridization of the first generation and the ”behavior problem” in american mixed teens is a degeneration of positive combination of traits between the two subspecies.

      • Sandgroper says:

        Sounds like psycho-babble. I can think of any number of confounds. ‘Black’ in this content is actually ‘mixed’ of varying proportions, mostly. Lumping Hawaiians, half-Filipino, half-Hmong, and half-Chinese together as ‘mixed Asian’ would be really dumb, but people lump ‘Asians’ together all the time as if they’re all genetically and culturally homogeneous. Peer group environment sounds like it could be fairly confounding.

  4. agnostic says:

    My hunch is that the creative explosion was a result of contact between us and Neanderthals, though not from picking up their genes or culture. Rather, encountering an almost-human group made us more conscious of who we were as a group. Where we came from, what made us different from them, what makes us better.

    It wouldn’t happen if the group were too different — like when humans encountered cats or dogs. But something in the “uncanny valley” is disturbing, and gives us something worth contrasting ourselves against. It heightens our group and cultural consciousness.

    Cultural products that serve as ethnic markers or membership badges begin to flourish as we become more proud of celebrating who we are, and to keep our group bound together in the face of competition from the almost-like-us group. The group the celebrates together, conquers together.

    The idea doesn’t apply so well to more utilitarian inventions. But cave paintings and things like that, sure.

    The explosion of Aborigine art in Australia would’ve come from occupying the same land as Denisovans for so long, and being their competitors.

    Ditto the ancient ancient art of sub-Saharan Africa — whoever that archaic species was that they had to come together against.

    Far outside of s-S Africa, Western Eurasia, and Sunda / Sahul, competition wouldn’t have been as fierce and enduring, hence human cultural identity less necessary to mark, hence less of all that fancy stuff. Indeed, South Asia, East Asia, and Siberia / New World don’t have cave / rock paintings / etc. going back nearly as far as the three main sites of human-archaic competition.

    This doesn’t explain everything, of course, but it does pretty well and has some theory to motivate it.

    • Sandgroper says:

      Where the art is painted on surface rock exposures as opposed to within caves, it weathers with time, and people need to keep going back and refreshing it – which is exactly what Aboriginal people did in a lot of cases. In some places they still do. If they had not done so, a lot of that art might no longer be there to find. It also gives a problem with dating, obviously (although pictures of sailing ships and people wearing European-style hats are a bit of a give-away, as maybe are depictions of animals which appear to be animals that are now extinct and have been since the Pleistocene). Surface rock exposures are a nice canvas to paint on, as inviting as the side of a building is for modern graffiti, and not too bad preservationally compared to lots of other media, but a lot less good than subsurface exposures protected from the weather.

      A possible confound might be that rock and cave art happened where there were suitable rock faces exposed to paint or carve on. Art in less preservationally favourable media might have happened, but it’s no longer there to find.

      Not saying it invalidates an interesting theory, necessarily, but the absence of evidence is not evidence of absence, and it’s maybe worth thinking about the media available for tagging and how durable it was over a time span of several tens of thousands of years.

  5. agnostic says:

    That idea was partly inspired by Julian Jaynes’ view of the proximate cause behind the breakdown of the bicameral mind and the dawn of self-awareness, introspection, etc. Namely, when two groups met that came from quite different ways of life, such as herders and nomads bumping up against settled farmers — not just here and there, but once that became a regular feature of life.

    That makes you naturally ask what is so different about them, that makes them them? They must have some inner, essential difference. But if they have a different essence, then we must have our own essence — state of mind, inclinations, tastes, hopes, fears, and all the rest, that make us us.

    Hunter-gathers who only encounter other hunter-gatherers aren’t going to raise that many questions about the inner workings of the human mind or spirit.

  6. jb says:

    I’ve always wondered about the hair. It does seem, more than anything else, to be the feature that distinguishes sub-Saharan Africans from the rest of the world (at least in appearance). It would be really interesting if it came from the Neanderthals.

    I also wonder whether the relatively high level of Denisovan admixture might not have had an effect on the appearance of the native peoples of Australian/New Guinea. To my eye they have a “primitive” look beyond even what you see in sub-Saharan Africa.

  7. Jim says:

    Depression maybe makes you less active so you burn up fewer calories. In the northern winter you need to conserve energy. Dancing like a Brazilian is all very well but it wastes a lot of energy.

  8. Jim says:

    Sandgroper – I lived in Guam which is well into the tropics when I was a kid. There is officially a dry season and a wet season but to me that wasn’t very noticeable, Ir rains a lot all year around. The seasonality of tropical cyclones is of course obvious. I remember noticing that summer was a little hotter than winter. This seasonal effect is small – the average high in June is 88.8 versus an average high of 86.3 in January. Despite this small difference I was aware of it. I was completely obllivious to the slight variation in the length of the day.

  9. panjoomby says:

    if we weren’t all friendly-like with neanderthals, but rather were in direct & fierce competition with ‘em – that might amp up natural selection… if the neanderthals had poor language skills they may have had better visual-spatial skills – which may have benefited us. it’s still too cloudy to see what was going on. & freakin’ “depression” research is so muddy it ain’t’ gonna clear anything up. eventually the clouds will part :)

  10. Greying Wanderer says:

    “I would say it was obvious, if that word meant anything.”

    I would say it meant that sometimes one or more of the steps in the logic chain seem so obvious they get missed out.

    .

    SAD = quasi-hibernation?

    this would require storing food in advance

    .

    “bigger populations cause more favorable mutations…the “great leap forward” 40,000 years ago”

    So any mutation around or before that time that led to higher populations could be the cause of a lot of other stuff that followed.

    Sudden random thought – could de-pigmentation among Neanderthals in northern latitudes (with the red hair and freckles gene etc) as a quick way to get more UV have caused more mutations (because of too much UV)?

    .

    “When it comes to admixture of hominids from various continents the world becomes middle eastern centric. After all that is where the continents of Africa, Europe, and Asia join. And indeed that is where a small population of anatomically modern men and Neanderthals started their expansion to the rest of the world.”

    Interesting thought – where would the prime contact zones be? For example if the Med was a border there’d be less contact so you’d have Middle-East? Himalayas? somewhere in East Asia?

    .

    “I’m kind of curious to know whether the EDAR gene variant carried by East Asians was derived from the second pulse they got”

    I wonder something similar as my current model is
    1) out of tropics
    2) out of Africa (khoisan looking)
    3) out of India (sub-tropical Indian looking?)
    so if (3) won the battle against (2) in most places and if East Asians got the epicanthic fold from (2) then they’d have needed a big extra advantage over (3) to win that regional contest.

    .

    Paradox of human raider populations is they eventually turn into their prey. Not sure if that’s relevant but it’s interesting.

  11. Greying Wanderer says:

    If you assume that humans adapted to different latitudinal climate zones in sequence and combine that with the idea that higher populations have a higher chance of beneficial mutations and then apply both to a surface area map (adjusted for presence of low density terrain like deserts).

    http://www.wallpaper.com/galleryimages/17050623/gallery/testuser5_oct2008_08_atlas_jp211008_62uNRQ_EVU8Kl.jpg

    Then you should be able to roughly guess at least the early parts of the sequence.

    Looking at the map for the region with the largest tropical surface area it’s clearly going to be either Africa or South America (and i wonder if the Americas had been isolated a lot longer maybe a second species would have developed in Brazil (interesting idea for a sci-fi novel)) but Africa seems to have won that first race. So spreading out of the African tropics into the global sub-tropics.

    Second stage – adapting to sub-tropics. Again looking at the surface area map for the next latitude band and adjusting for desert areas i’d give it to India with Arabia and Africa (or Africa/Arabia combined) maybe close behind. (This would imply CF as India and out of India diaspora with D as SE Asian derived variant, E as Arabia/Africa derived variant and F as the root for the rest.

    Third stage – adapting to mid-latitudes. Looking at surface area getting a bit harder to see any single clearly winning region. Candidates: North Africa and Southern Europe, Near and Middle East, Iran/Northern India, Southern China. Or all of them separately (GHIJK etc).

  12. On QI it was stated that the French used to ‘hibernate’ by which was meant a high degree of winter inactivity. Does anyone have any information on this? It seems like a strange claim but it feels worth following up to see the truth in it.

  13. Richard Sharpe says:

    OT, but if this turns out not to be a fake report of Underwater Pyramids from 20,000 years ago, I blame Phssthpok.

  14. >. In the US, blacks have Type 2 diabetes rates that are about twice as high as whites.
    Yes, but most US blacks have some European ancestry.

  15. TWS says:

    I went from living and working in a place that got decent UV and sunshine to a dim light-starved rainsoaked wasteland.

    The populations were not completely identical but numerically they were nearly identical. However, the differences in suicides and attempted suicides were huge. One suicide in around five years in the normal sun (no murders). Maybe three actual attempts out of @ 5,000 people.

    The rainsoaked place eight suicide attempts and five suicides. Three murders and one maybe murder counted as suicide.

    • The fourth doorman of the apocalypse says:

      to a dim light-starved rainsoaked wasteland.

      You shouldn’t talk about Seattle like that.

      • TWS says:

        Seattle gets about a third of the rain and far more sunny days. It’s practically Monacco by comparison. And Ballard formerly home to elderly, gloomy Scandinavians and their grandparents (a district in Seattle) was Las Vegas for rollicking good humor.

  16. Greying Wanderer says:

    @Little Spoon

    “So, if we leaped forward because of genes from them, those same genes weren’t working for them in the way that they worked for us.”

    Imagine an ugly model with a cute nose and a cute model with an ugly nose.

    The cute nose doesn’t do much for the ugly model but if the cute model gets the cute nose she gets a lot cuter.

    .

    The question is what was the cute nose. Has anyone ever tested if African type hair has a coolant effect on the same principle as a heat sink? Or if straight hair has a warming effect? (I can imagine someone doing a study into any difference in heat loss from hair vs bald at least.)

    http://www.bksautoindustries.com/images/heatsink5.jpg

    According to this

    http://www.livescience.com/34411-body-heat-loss-head.html

    we lose 7% of body heat through the head – unless everything else is wrapped up warm and only the head is exposed when the percentage is a lot higher – so if straight hair has a warming effect then might that be a difference of 1-2% in energy requirements?

    • little spoon says:

      “Imagine an ugly model with a cute nose and a cute model with an ugly nose.

      The cute nose doesn’t do much for the ugly model but if the cute model gets the cute nose she gets a lot cuter.”

      Why do people think I have a problem comprehending this? Can you read my post? I stated the exact same thing in an analogous example-

      “Like you could be half black and half Japanese and have excellent spatial reasoning and great rhythm”

      • Greying Wanderer says:

        Okay fair enough. I read

        “So, if we leaped forward because of genes from them, those same genes weren’t working for them in the way that they worked for us.”

        as you not getting how easy that is to be true.

        You’re saying it’s not the *best* answer.

        “Technically, Neanderthal genes might have contributed to a leap in intellectual capacity, but saying that we received an influx of Neanderthal genes is not the best answer for why we advanced suddenly.”

        I’d say it’s easily the best answer if it had anything to do with IQ and probably the best answer if it had anything to do with population growth but yes if its not related to either of those then yes there are probably lots of others that are plausible.

        How might it be to do with IQ?
        -skull size?
        -lighter skin synthesizing more of something useful for babies in breast milk?

        If so, just for example
        – hominid series A, average 60 IQ, in northern latitudes develops larger skull +5 points and something breast milk related +5 points, new total 70.
        – hominid series B, average 70 IQ, evenly matched by the A+ series hominids, over time pick up skull and breast milk enhancements +10 points, final score 80, bye bye Neanderthal.

        If it took Neanderthals 100 generations to develop those advantages but AMH got them in 10 then it would look like a sudden jump.

    • JayMan says:

      @G.W.:

      I have kinky African hair, and I shave it in the summer so my head doesn’t overheat.

      In the winter, the Afro makes a nice hat.

      • Greying Wanderer says:

        shame, i liked the heat sink idea

      • Sandgroper says:

        Don’t ditch it yet – it depends on whether JayMan spends all summer walking around under the merciless African sun with no hat on, and how cold the winter is.

        You could do empirical experiments on Afro length in varying climates to determine when the hair serves more as insulation to prevent heat escaping, and when as insulation to prevent excessive absorption from the sun.

        If I shave my head in summer, it means I’m cooler in the shade, but I definitely have to wear a hat out in the sun. In winter, if I don’t wear a hat outside, the heat loss from the head is really major.

  17. Philip Neal says:

    FOXP2: A lot surely depends on whether Neanderthals could make the same speech sounds as modern humans. It used to be said, on the basis of work by Philip Lieberman, that they were physically unable to form the full range of human vowel sounds within the ‘vowel triangle’ a-i-u, but I understand that more recently this has been challenged. If Lieberman is right, at the very least Neanderthals would have been unable to speak the languages of modern humans properly, and some have gone further, to claim that the whole hierarchical nature of human language derives from the hierarchical structure of the syllable, which in turn depends on the vowel system.

  18. Rum says:

    When the subject is genetics, the best first answer is, “This is complicated.” And it is, of course.
    On the other hand, the selection pressures unique to life in the North – cold weather, long dark winters, etc. were applied to Neanderthals for about 10 times as many generations as to any other human sub-species. The Inuits just got there from Africa, by comparison.
    Food for thought.

  19. little spoon says:

    The range of Neanderthal in Eurasians is about 1-4%, yes? What is the absolute upper and lower limit observed on those (for those with no recent sub saharan ancestry)

    Is there any chance- as in any chance above zero- that you could create comparison groups between people within the same ethnicity that had high Neanderthal ancestry vs. low and observe psychological differences? Like, if you looked at Lithuanians with 4% Neanderthal ancestry and a separate group of Lithuanians with .7% Neanderthal ancestry, could you do an extensive compilation of their mental profiles to see if there is any difference between the groups- like verbal reasoning, propensity to anxiety, opennes to experience etc. Then compare the differences (if there are any) in the Lithuanians to differences in high Neanderthal vs. low Neanderthal people in other completely different ethnicities. Is it possible that there would be a pattern of where the differences were once you did this for a sample of many nationalities? Like maybe people with high neanderthal mix would have higher spatial reasoning, greater propensity to agression etc. I can see that this study is pretty unlikely to work being that those with high vs. low Neanderthal ancestry from the same region have been under the same selection pressure for so many thousands of years, so maybe they have all developed compensating traits, but is it possible that this experiment could work at all?

    • gcochran9 says:

      How much total Neanderthal ancestry anyone has is not the point. The point is which particular alleles one has, and the effects of those alleles.

      • little spoon says:

        If we look at what we have of remains of people who lived 40,000 years ago, can we tell if they were also 1-4% Neanderthal? Or might some of them been 30% Neanderthal and others 0%? Did people then have more Neanderthal genes that we no longer have now which may have been useful at the time?

      • dave chamberlin says:

        Otzi the iceman was 5.5% neanderthal, before that lucky find of a man frozen in the ice there is a combination too few well preserved bones and too few David Reich competent scientists looking at what we have. We do have the bones and they definitely point to a higher percentage of neanderthal in at least some individuals which show marked neanderthal characteristics. Sandgroper has raised some interesting points about a second pulse of breeding with neanderthals with East Asians, sounds fascinating and I hope to encourage more threads by Cochran on this evidence as I know nothing about it.
        Readers might dismiss these discussions on how we evolved a higher intelligence as interesting but really just another ancient history discussion. It is a whole lot more than that because the big story of better brains, past, and present when sorted out will lead to mind blowing options for our near future.

    • Sandgroper says:

      Current estimate is 1-3% overall. This average includes regions where it is much higher, and indeed the majority (Majority of the %, not majority of the regions).
      The standard deviation in Neanderthal ancestry among individuals from within the same population is 0.06–0.10%, in line with theoretical expectation, showing that Neanderthal ancestry calculators that estimate differences on the order of a per cent are largely inferring statistical noise. (I’m quoting here, obviously) (so no 4% Lithuanians and 0.7% Lithuanians).
      Neanderthal ancestry is inferred to be as high as 62% in East Asian and 64% in European populations in specific regions.
      East Asians have 21% more overall than Europeans, which they received in a second pulse after divergence.
      (Now me extemporising): This suggests that it must be high in some regions for East Asians but low or absent in those regions in Europeans.
      This supports GC’s observation – the place to look is at the specific regions where it is high, and it may be particularly informative to compare these regions between Europeans and East Asians.
      It’s a no brainer that during at least two periods in the past, there were people who were 50%. Some were probably sterile, so looking at them would be uninformative.
      I think I’m right in saying the oldest modern human who has had full genome coverage so far is 24,000 years old.
      If the plan is to sample enough 40,000 year olds to determine distribution within a population, good luck with that.
      “Interbreeding of Neanderthals and modern humans introduced alleles onto the modern human genetic background that were not tolerated, which probably resulted in part from their contributing to male hybrid sterility. The resulting reduction in Neanderthal ancestry was quantitatively large.” IOW, anything that was mal-adaptive probably disappeared pretty quickly.
      Corrections welcomed.

      • Sandgroper says:

        Hair, skin, teeth, sweating and lactation might be likely looking candidates.

        Shovel shaped incisors are relatively more common in East Asians.

        The composition of European and Chinese breast milk is not the same. That has a kind of adaptive-ish ring to it.

      • little spoon says:

        “Neanderthal ancestry is inferred to be as high as 62% in East Asian and 64% in European populations in specific regions.”

        What?

      • Sandgroper says:

        Sankraraman et al. (2014): “The Neanderthal introgression map reveals locations where Neanderthal ancestry is inferred to be as high as 62% in east-Asian and 64% in European populations.”

      • dave chamberlin says:

        Certain LOCATIONS are inferred to be as high as 62% in East Asians and 64% in European populations. Just thought I’d emphasize that as it confused me at first and probably did little spoon as well.

      • Sandgroper says:

        Sorry, I should have said locations.

  20. Rum says:

    Little Spoon
    Humans with 50% Neanderthal genes once walked the Earth. I mean, if any N genes survived at all…

    • little spoon says:

      Yeah, it must be the case that once some people were 50% Neanderthal and others were 0. I am wondering what that distribution was 40K years ago. When did we get to 1-3% Neanderthal? Like 20K years ago, was it 1-10%?

      I think if we map every single Neanderthal gene we have now, that will actually tell us what genes were selected over the last few thousand years based on recent selection pressures (though of course they were also there before).

      40K years ago, if people had different Neanderthal genes, those may have been vital at the time. And at some point, there must have been human-Neanderthal pairs, maybe even some with long relationships. What if Neanderthals were like a minority that was useful for a few niche things in a tribe? Like how now a football team typically benefits from a white quarterback and a black running back. Maybe Neanderthals were dim but they could really thrust a spear through a thick hide, so it was useful to have one of them on your hunting team. So maybe even somehow the portion of people with Neanderthal genes was indicative of something useful at one time. Like it was best if 20% of the tribe had them, but not everyone. And that sort of thing would change over time as cultures and other things changed.

  21. Greying Wanderer says:

    @LS
    “Neanderthal ancestry is inferred to be as high as 62% in East Asian and 64% in European populations in specific regions.”

    “What?”

    62%-64% in regions of DNA for example some of the regions dealing with skin, some of the regions dealing with teeth, some of the regions dealing hair etc.

    If Neanderthals had had 100s of generation adapting to a colder environment then the specific regions of DNA connected to those adaptations might be the ones that had more benefit than cost.

    • Greying Wanderer says:

      “Hair, skin, teeth, sweating and lactation might be likely looking candidates.”

      Hadn’t thought of sweat glands in this context but yeah.

  22. Sandgroper says:

    The really irritating thing about bright people is that they say stuff that, after they’ve said it, seems like it should have been obvious.
    http://www.unz.com/gnxp/open-thread-222014/
    I suggest people don’t rush over there and wildly speculate, BTW – Razib is so damned good that I’ve been reading him continuously for 11 years, but he has a less relaxed policy on comments than Greg and Henry.

    Anyway, Razib’s point, which is obvious now that he’s said it, is that Neanderthal alleles are not ‘fixed’ at any specific loci in any population – the maximum frequency is 60+%, not 100%. So logically it should be possible to learn a lot from looking at phenotypic effects within populations.

    What seemed obvious to me is that there is also a surprisingly big difference in the means of two different and readily groupable geographic populations, the people from the west side and the people from the east side of a big land mass. So it should be possible to learn a lot from both within population variation and between population variation in phenotypic effects. A possible confound might be that Chinese people seem to have some very small amount of Denisovan ancestry as well, but maybe it’s so small it doesn’t matter too much, or you could just group it as ‘archaic’ or something. No idea.

    Quoting from the synopsis: “We have shown that interbreeding of Neanderthals and modern humans introduced alleles onto the modern human genetic background that were not tolerated, which probably resulted in part from their contributing to male hybrid sterility. The resulting reduction in Neanderthal ancestry was quantitatively large: in the fifth of the genome with highest B, Neanderthal ancestry is 1.5460.15 times the genome wide average 22. If we assume that this subset of the genome was unaffected by selection, this implies that the proportion of Neanderthal ancestry shortly after introgression must have been >3%rather than the approximately 2% seen today.”

    I’m struggling a bit with some of that because, in addition to being a biological idiot, I don’t have access to the full paper. But they obviously know that immediately after a hybridisation event (or ‘hooking up’ as some choose to call it) the proportion of Neanderthal ancestry of the product of that event was a lot more than >3%. They seem to be saying clearly that lots of it disappeared pretty quickly, but not all of the stuff that is missing now. It depends what they mean by ‘shortly’, but they seem to be saying that ‘shortly’ after introgression, the proportion of Neanderthal ancestry was somewhat higher than it is now. But not lots higher. So there was some stuff that stayed for a while, but was not sufficiently adaptive to be retained up to now. Given that the mean is now about 2%, saying “>3%” does not mean very much higher, it means a bit higher. ‘Shortly’ does not mean the very next generation, obviously; it means, in terms of the span of modern human existence, it was not that long after a hybridisation event that the proportion of Neanderthal ancestry in that population had reduced to something like 3+%. Not 30%. But it was not as low as it is now in any population, which is around 2%, plus or minus a %.

    The other interesting thing, it seems to me, is that the variation in mean total Neanderthal ancestry within any population is not that much. But at any specific locus, the maximum frequency is only 60+%. That must mean, that within a population, everyone has roughly similar total amounts of Neanderthal ancestry, but at specific loci, some people have it and some don’t, within the same population. It seems to suggest that at any specific locus, the alleles were not so advantageous that they have gone to fixity – not yet. It was not some “hammer blow of selection” like lactose tolerance, which happened much more recently, but is near fixity in north west Europeans.

    • Greying Wanderer says:

      “It seems to suggest that at any specific locus, the alleles were not so advantageous that they have gone to fixity – not yet. It was not some “hammer blow of selection”

      Is it possible to tell if some of these alleles went to fixity and back i.e. if the Neanderthal alleles were a quick beneficial fix but came with negative side-effects, so in some cases improved versions of these alleles have developed since which have been gradually over-writing the Neanderthal stuff?

      • Sandgroper says:

        I don’t know. Razib calls this a “big surprise” (that the maximum frequency at any location is only 60+%). It is.

      • Sandgroper says:

        I think the thing to get is that the loci are varying within populations, but the standard deviations are not that big on the total within populations. That’s what I find the most mind-bending.

      • dave chamberlin says:

        Reading Razib Khan’s blog over the years has been an enlightening as well as humbling experience for me. If readers like West Hunter I reccomend the blogs of John Hawks and Razib Khan whom are good friends of Greg Cochran. I make admittedly snide comments about the normal folks but I have also come to realize there are those individuals out there way smarter than me whom have worked hard for decades on becoming experts in a particular area. A wise person admits how little they know. There is a wonderful saying in China regarding staying humble, “If you are one in a million there are still 1300 just like you.” That is wierd that the maximum frequency of neanderthal alleles at any location is +60%. As I understand it genes that are advantageous ever so slowly climb to 15% than move rather quickly depending how advatageous they are to 80%, than move slowly again towards 100%. So advantageous genes introduced from Neanderthals stuck at 60% is a mystery.

  23. Sandgroper says:

    Depends on what you take as a population, I guess.

    • Sandgroper says:

      “Regions that harbour a high frequency of Neanderthal alleles are enriched for genes affecting keratin filaments, suggesting that Neanderthal alleles may have helped modern humans to adapt to non-African environments.”

      But those environments varied, both temporally and spatially. People have hardly been static geographically since the times the hybridisation events occurred – on the contrary. Plus climate variation with time. Something that might have been adaptive could become less adaptive, for different people moving into different areas at different times.

      So it seems to me that what you are suggesting could be possible. If you take a north-western European, move him to East Asia and mix him with East Asians, lactose tolerance is not going to remain at fixity in subsequent generations – some will have it, some won’t.

  24. RS says:

    > It seems to suggest that at any specific locus, the alleles were not so advantageous that they have gone to fixity – not yet.

    Heterozygote advantage is one possible reason. Frequency-dependent selection can be another, but intuitively doesn’t really light my fire in this context.

    That said I share your puzzlement. It seems like some alleles should just be straight-up better and fix pretty soon.

    • Sandgroper says:

      Heterozygote advantage reads to me like a possible, but my biological illiteracy is giving me trouble. I think it’s worth listening to this BBC interview that someone posted on Zeeb’s blog – it gives the researchers’ take on what was advantageous or maybe mildly disadvantageous, as far as they are willing to commit at this point. They’re being cautious, obviously. There’s also some irrelevant but cool stuff on Bubonic Plague. http://downloads.bbc.co.uk/podcasts/radio4/inscience/inscience_20140130-1700a.mp3

  25. Greying Wanderer says:

    “So advantageous genes introduced from Neanderthals stuck at 60% is a mystery.”

    If you assume all Neanderthal DNA had a negative effect on fertility due to being diverged but some specific pieces also had a substantially positive effect on fitness in one specific area would you expect eventual fixation or some kind of balance between the two effects?

    (just wondering)

  26. Greying Wanderer says:

    “Regions that harbour a high frequency of Neanderthal alleles are enriched for genes affecting keratin filaments, suggesting that Neanderthal alleles may have helped modern humans to adapt to non-African environments.”

    @Sandgroper
    “But those environments varied, both temporally and spatially.”

    The alleles that spread may have been different at different times depending on the contact zone i.e. some early ones in mid-latitudes relevant to mid-latitudes, some later ones only when the contact zone moved into northern latitudes. For example say AMH got straight hair and partial albinism from Neanderthals in Northern India but the albinism was strongly selected against and never spread while the straight did (for some reason). Then later the now straight-haired AMH move further north and the same alleles are passed over but this time the partial albinism is not selected against and spreads.

  27. Gottlieb says:

    ”Sounds like psycho-babble. I can think of any number of confounds. ‘Black’ in this content is actually ‘mixed’ of varying proportions, mostly. Lumping Hawaiians, half-Filipino, half-Hmong, and half-Chinese together as ‘mixed Asian’ would be really dumb, but people lump ‘Asians’ together all the time as if they’re all genetically and culturally homogeneous. Peer group environment sounds like it could be fairly confounding.”

    In ”America”, the majority of black population aren’t much more mixed, there a difference between ”10-20% mixed” and ”40-60%”. mixed. Minority of them are ‘mulattos”. East asians and sout east asians once for all aren’t exactly the same thing. Think in the second group like middle eastern to europeans (caucasoid branch).
    When i talk about ”asians”, ”blacks” and ”whites”, i talk exactly of people which second its research define yourself according their owns self-ethnoperceptions, only.
    Yes, majority of american blacks are slightly mixed but they continue predominantly blacks in behavior and self community-identification. I learn when two people with different subspecies or geographical isolated populations mate, the ”archaic” traits of this two groups emerge.
    I’m only suggesting that many psychological traits overwhelming presents in eurasians like introversion and hard work could be part of ”neanderthal psiquè”. Mental disorders and your respective (advantageous) degrees could be the result of this mate between homo sapiens e neanderthal, if this mate really related directly with increase of brain and intelligence since the mutations related to autism and other conditions related to ”development and increase” of brain.

  28. RS says:

    > If you assume all Neanderthal DNA had a negative effect on fertility due to being diverged but some specific pieces also had a substantially positive effect on fitness in one specific area would you expect eventual fixation or some kind of balance between the two effects?

    Eventually the good part should become isolated from the rest in some individual. Who should then kick * and take names.

    Because genomes break up and remix. During meiosis to produce sperm/ova, you get some recombinations of chromosomes.

    I’ll assume you’re male and use ‘you’ for ease of style. In each sperm-precursor cell, as in every other cell of the body, you have one chromosome-6 from your mother, and one chromosome-6 from your father. And likewise for chromosome-8 ; chromo-6 is just an arbitrary example.

    But the two chromo-6’s will often exchange portions during meiosis, so that very roughly half of the sperm cells have a recombinant (‘hybrid’) chromosome-6, derived partly from your mother and partly from your father. The other sperm cells have either the maternal chromo-6 or the paternal one, unaltered. (But chromo-6 never trades pieces of itself with chromo-8 in this way — actually, I think it does sometimes happen erroneously, but is an utter disaster in 99.999999% of cases.)

    For this reason, if I’m not messing this up, one is “50% genetically identical” to siblings (and “25% identical” to grandparents) only on average. The real value is prolly gonna be 0.486 or 0.502, so its not materially different from 0.5000 . . . just a curio.

    With your /parents/, assuming you treat the X and Y as equal (if you are male), it /is/ exactly 0.50000.

    Each sperm or egg carries about 25 recombinations on average, in man, IIRC.

    Analyzing this stuff is the way — the primary way, that I ever heard of — that guys like Cochran estimate the recentness and rapidity of selection of a new allele. (Without adjunct use of info from fossil DNA, which can surely yield a fuller picture of things.) Lactase persistence arose very recently, and very rapidly. So there has not been time for it to become broken off from very much of the millions(?) of bases found on either side of it when it first occurred. So all lactophages, or most of us, have a very long bloc of DNA containing the small number of important fitness-enhancing bases. Some of the bases/ sequences of bases found in that bloc might be slightly harmful ; prolly most are neutral or epsilon. If you check back in 150,000 years, there probably won’t be much of a bloc there anymore because the above-explained recombination will gradually whittle it down, which is called linkage disequilibrium decay. In a million years, the bloc will be smaller yet.

    • RS says:

      Assuming that’s pertinent to what you had in mind. I’m a little out of it at the mo.

      • Greying Wanderer says:

        My thought was that highly divergent DNA might effect miscarriages for similar reasons to organ transplants being rejected so there might be strong selection to get rid of all of it for that reason only balanced or overmatched in specific areas if there were very strong advantages in those areas. If so you wouldn’t expect it to get to fixation but to some balance point.

    • Dan says:

      There is a good chance that Neanderthal genes have been reduced since the advent of grain and dairy consumption. Those genes may have been more useful while humans were still hunter gatherers. We are probably not quite the same humans our ancestors were 12,000 years ago. One funny anecdote is the Venus Von Willendorf as a near ubiquitous figurine over much of Eurasia. A big fat boobs and butts hand held sculpture. With settled life we see Egyptian type standardized torso and profile. The brain hardwiring changed some time between the chubby Venus and the lithe walking Egyptian. Has DNA with trace Neanderthal DNA been extracted from 12,000 year old samples? 5,000 year old samples and cross checked with agricultural practices?

  29. Dan says:

    Jumping in here.

    Is abstract reasoning something we have proof of either humans in pre OOA East African populations or Neanderthals?

  30. Dan says:

    My understanding of the Out of Africa event is that a very small number of humans either swam or rafted across from Djibouti to Aden. Maybe 200 quite closely related individuals. Can one assume that they were a clan or small tribe? Is it possible that they were immediately interbred with a few of the Neanderthals they encountered once they landed? Or does the evidence suggest it happens later in Europe or in Central Asia?

    My instinct is that the intrepid swimming/rafting group were organized and either running away or deliberate colonists. What sort of group would risk the 8-11 mile sea voyage? perhaps they were already distinctive in some way from the locals that they were moving away from. They were not followed by anyone either if the DNA evidence is reliable. Then they interbred with Neanderthals!

    I think they were already an isolate population of some sort before they crossed.

  31. Rum says:

    I was born with green eyes and red hair. My ankle and knee joints are unusually thick. Not for me was there ever a “turned ankle”. The attachment points for tendons are weirdly extended past the joints. This produced a greater mechanical advantage at the expense of fine co-ordination. I was a demon wrestler in college. (the real kind, not the TV kind). 4%.
    There was, back in the late 60s,a British folk band called “Pentangle”.
    Neanderthals had music. You can hear what it sounded like on U tube.

  32. Gottlieb says:

    I think some of you are confused. If it is likely that Neanderthals were not much better than the homo sapiens, this is not the main issue. What matters here are not the traits of Neanderthals, but the combination of these traits with the traits of Homo sapiens, because we are talking specially adapted hybrids. If depression is actually part of Neanderthal heritage in us, then there exists rather a beneficial relationship, since it relates considerably with creativity. If Neanderthals were actually on the verge of speciation during the period of racial mixing with sapiens, then a relatively rare event and only could have happened. For a species to be very close to speciation, she must have suffered previously with the maturing of their genes, making them fixed. If Neanderthals had larger than the current average human brains and actually had produced sapiens similar to the technology, so there seems to be very prickly deduce that in fact, some important cognitive advantage this combination should have caused to result in huge disparity in cognitive abilities differences between the groups with the largest presence of visible legacies and their genetic and SSA.
    I believe the theory, autism and Neanderthal, may be partially correct and that most neurological problems and mental disorders, are some of the results of this hybridization. I mean, it could be a hypothesis as always, far from being correct, but anyway, that if Neanderthals were much bigger than ours and that of homo sapiens, so when the two mingled , one result of this hybridization was the manifestation of autism spectrum (and more broadly, introversion). Larger brains, more neurons behave and this can result in lower socialization. Recently, if I understand right, it was shown that one of the explanations for the inability of full socialization of the autistic population would take place because of excess neurons. It is assumed that a lower capacity for socialization result in less development of complex language. Asians may have inherited this part of neanderthal heritage, large brains, modest socialization and development of a simpler language.
    The idea that a species will also enter into a long process of speciation, also seems wrong, only if Neanderthals were all genetically similar. But if there were several types of them, so I believe that some types could be more distant from speciation in relation to others, the natural internal variability that occurs in all races. Some are more psychologically archaic, others are more physically modern, anyway.
    I believe that creative people tend to be genetically different, at least in relation to their behavioral phenotypes. One result of hybrid vigor may be a combination of disparate traits, I mean, you have a race where the average person is introverted, and another race where the average personality is extroverted. When these two are mixed breeds you have, as we know, several phenotypes resulting from this mix, entitled In the expression of a phenotype in which there shall be no predominance of personality or an internally conflicted personality. Creative people are generally so they are both introverted and extroverted.
    I start from the idea that people tend to migrate to other countries, tend to be more extroverted or at least, more high risk than people who do not migrate. More introverted birds tend to explore less territory than the more extroverted birds. Homo sapiens high risk (adhd?) Parted from the rest, or even, even there was a real separation because they could not be historically related, and were exploring new territory. Neanderthals, who tend to be more introverted then mated with sapiens. You have a race with mature psychological traits, mingling with a population with greater socialization.
    It is also important to consider what were the social and psychological effects of hybridiization for this groups. Rape or discocaverntec??

  33. Pingback: linkfest – 02/17/14 | hbd* chick

  34. Doug Hensley says:

    It’s a beautiful analogy about the T34 and the PzKW MkIV, but one little point is got backwards. The T34 had better mechanical reliability than did the German tanks of the time. Think about it: the T34 didn’t have many iterations and it remained in production as pretty nearly the same tank the whole way through the war. The Germans, by contrast, were constantly introducing new models. As with new car models, there’s teething troubles. As an avid history buff and historical wargamer, I can report that essentially all sources agree on this point. The T34 was simple and rugged.

    But yes, not having radios in all the tanks really hurts. It’s one of those intangible force multipliers that so often makes all the difference. For all its merits as a tank, Soviet tank losses in the big tank shoot-out of the war (Kursk) ran something like 8 to 1 higher than German losses. Not that this was good enough to win the battle for the Germans. T34’s were cheap and were rolling off the lines in mass quantities.

    • gcochran9 says:

      Not in the beginning. ” it was not uncommon for early T-34s to enter combat carrying a spare transmission on the engine deck.” They also had lousy air filters. Things got better.
      After Kursk it was obviously time for a better gun, hence the T-34-85

  35. Pingback: Predictions on the Worldwide Distribution of Personality | JayMan's Blog

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