I was reading a recent and yet unfinished paper (K H Ko, 2015 ) 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)" .
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)  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 , the frequency of the most common haplotypes among different populations:
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.
 K.H. Ko, (2015). Evolution of Intelligence and History of Interbreeding, researchgate.net
 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 ©