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Guide to Patagonia's Monsters & Mysterious beings

I have written a book on this intriguing subject which has just been published.
In this blog I will post excerpts and other interesting texts on this fascinating subject.

Austin Whittall


Sunday, December 27, 2015

SLITRK1 and the peopling of America


I was reading a recent and yet unfinished paper (K H Ko, 2015 [1]) about the admixting history of humans (H. sapiens, Neandertal and Denisovans) with a rather different point of view to what one usually finds in this kind of paper. One thing that caught my eye was the following sentence: "Genetic studies have shown that the ADSL, GLDC, and SLITRK1 genes, which are linked to hyperactivity and aggressive behavior in modern humans, are not found in Neanderthals (Castellano et al., 2014)" [1].


Of course, I checked Castellano et al. (link) and found that they had actually written the following, regarding those three genes: "Thus, it is possible that the mutations in these genes may have affected some component of behavior unique to modern humans. However, we note that even if they did, the way in which they occurred is unknown. For example, if they affected activity or aggression levels, it is unclear whether they increased or decreased such traits. In any event, these changes clearly warrant further investigation."


So maybe the Neanderthals were the violent ones and we were - are the peaceful ones.


But I decided to check the global frequency of this SLITRK1 gene which is linked to Gilles de la Tourette syndrome (GTS), a neuropsychiatric disease which causes involuntary and repetitive movements and vocalizations (i.e. "tics").


And I came across a paper by Speed et al., (2008) [2] which describes a section of this gene and its different haplotypes. They found twelve haplotypes all of which derive from an ancestral haplotype which they inferred from genotyping non-human primates. However this ancestral form was not seen in any population. They found that the existing ones can be arranged into two separate branches from the ancestral one and they show in Fig. 1 in [2], the frequency of the most common haplotypes among different populations:



Fig 1 and Fig 2 in [2] SLITRK1 haplotypes

The interesting thing in that figure is the high frequency of Haplotype #3 among South Americans, Pacific Islanders and North Americans. Obviously these are Native people. In black, above. These are found at much lower frequencies elsewhere. Among South Americans Haplotype #1 which has the highest global frequencies of all Halpotypes, is lowest.

Now Haplo. #1 is in the same branch as Haplotypes #8, 12, 9, 4, 5 and 10. And is highest in Africa and Europe. While Haplotype #3 (more frequent among Amerindians and Pacific Islanders) is on the other branch with Haplos. 6, 7, 2 and 11.


Haplo 4 is most common in Africa and absent in the other regions. It is also 4 mutations away from the Ancestral type. Haplo 6 is highest in Africa and found at similar frequencies in the Americas. It is only 1 mutation away from the Ancestral form. And Haplo 3 is derived from #6 by one mutation. So it is 2 mutations away from the Ancestral type. Placing it at the same distance as haplos #12 (very rare) and the most prevalent #1.


Once again we have an unusual American frequency distribution. And including a type (#3) close to the ancestral one... does this imply it is an "old" type?. It is also on the same branch as #6 (from which it derives), found mainly in Africa and... the Americas. Could this imply some archaic population? Common to Africa and the Americas?


One could argue with the typical "Bottleneck" explanation that America was peopled by people carrying those specific haplos. and that they then diverged and expanded due to this founder effect beyond the original frequencies. But note how East Asians and Pacific Islanders have even less diversity than Amerindians! (3 haplotypes vs. 4 among Americans).


Haplo. #7 is two mutations away from #6 (so it is further away - ergo younger- than Haplo #3) and found at very low frequencies in Africa but... it is highest in SW Asia, followed by Europe and N.E. Siberia.


We could surmise that #3 is the oldest variant (the equivalent one, #8 on the other branch, is found at very low frequencies so it does not appear in Fig. 1), and it follows the migration of H. erectus out of Africa, and survived among Africans and Amerindians, lost elsewhere. The next branch of the tree #7 derives from #6 (Neanderthals) follows their distribution Europe, SW Asia and, the backflow into Africa; followed by N.E. Asia. #3 also derives from #6 and may reflect the Denisovans? found among Pacific Islanders and Amerindians and, to a lesser degree in the other human populations (maybe via Neanderthal admixture?).


The other variants are on the "other" branch which represent "modern" H. sapiens and their late migration out of Africa (Haplo #1).


So we see a high frequency of an "old" (Haplo 3- in black) and a lower proportion (hence more recent admixture) of Haplo. #1 among Americans.


Sources
[1] K.H. Ko, (2015). Evolution of Intelligence and History of Interbreeding, researchgate.net
[2] William C. Speed, Brian J. O’Roak, Zsanett Ta' rnok, Csaba Barta, Andrew J. Pakstis, Matthew W. State and Kenneth K. Kidd, (2008). Haplotype Evolution of SLITRK1, a Candidate Gene for Gilles de la Tourette Syndrome, American Journal of Medical Genetics Part B (Neuropsychiatric Genetics) 147B:463–466



Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2015 by Austin Whittall © 

3 comments:

  1. Austin,
    Happy holidays,
    Your comment on the link to aggression struck a cord with me, concerning Neanderthal behavior.
    In the past, while reading a paper on the evidence of injuries in Neanderthal remains, I noticed that many of the catalogued injuries, could have been inter personal injuries. Broken cheek bones, fractured eye sockets, broken hands and arms, all the kinds of injuries one might get from fighting.
    There is solid evidence in the literature that the shape of our hands was as much driven by fighting as it was by manipulation of objects. Our faces have also evolved along with our fists to protect the eyes.
    Brow ridges in primates are also shown to have social purposes, scowling is a distinctive primate way of showing displeasure or a tool of intimidation.
    All of that being said, I firmly believe that there were social constructs that led to our displacing the other homonins we shared the landscape with.
    Neanderthal never lived in large groups, might it have been because they had a social system where interpersonal violence was prominent. Males had to fight for the right to mate, with younger males being driven from the group to start new groups, as we see in many mammal species. This kind of social behavior could lead to small groups where inbreeding was common.
    In contrast maybe us moderns had taken a more social approach to breeding and group building allowing us overtake the other archaic groups, with our cooperative breeding and ability to live in larger groups.

    ReplyDelete
  2. "Genetic studies have shown that the ADSL, GLDC, and SLITRK1 genes, which are linked to hyperactivity and aggressive behavior in modern humans, are not found in Neanderthals (Castellano et al., 2014)" [1].

    Those genes are not found in Neanderthals, so the related aggression is not Neanderthal, it is "modern" human. Neanderthals lived in the north, so they were likely less aggressive for more pleasant and bountiful territory. Maybe, they were more like Gorillas and humans are more like Chimpanzees. More accurate dating puts the extinction of Neanderthals further back. Anyway, smaller groups might only indicate the condition of their final days and injuries on the fossils might not be from infighting and we do not need fossils to prove that humans can be quite violent.

    ReplyDelete
  3. The word mutation was left out in the language editing process. Mutations in genes ADSL, GLDC and SLITRK1 linked to hyperactivity and aggressive behavior. The authors stated that it is hard to conclude whether this particular mutation relating to aggressiveness and hyperactivity would have increased or decreased such behavior. Nonetheless, from fossil evidence that shows massacre among homo sapiens 10,000 years ago, attack of Homo sapiens on Neanderthals, and the demise of Neanderthals began with the spread of homo sapiens. From evidence relating to homo sapiens and Neanderthal violence, Homo Sapiens would have been more violent one.

    http://www.sciencemag.org/news/2016/01/10000-year-old-massacre-suggests-hunter-gatherers-went-war

    Churchill, S. E., Franciscus, R. G., McKean-Peraza, H. A., Daniel, J. A., & Warren, B. R. (2009). Shanidar 3 Neanderthal rib puncture wound and Paleolithic weaponry. Journal of human evolution, 57(2), 163-178.
    The study indicates attack of Homo sapiens on Neanderthals
    Zollikofer, C. P., de León, M. S. P., Vandermeersch, B., & Lévêque, F. (2002). Evidence for interpersonal violence in the St. Césaire Neanderthal. Proceedings of the National Academy of Sciences, 99(9), 6444-6448.
    It was true that this showed interpersonal violence between Neanderthals, but the bone analysis indicated that the injury was not fatal. (Unlike attacks that happened between homo sapiens)

    ReplyDelete

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