tag:blogger.com,1999:blog-7785493.post3145534337208560855..comments2024-01-04T04:11:55.717+02:00Comments on Dienekes’ Anthropology Blog: Archaic human ancestry in East Asia (Skoglund and Jakobsson 2011)Dienekeshttp://www.blogger.com/profile/02082684850093948970noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-7785493.post-6152106029124684592011-11-02T11:51:43.191+02:002011-11-02T11:51:43.191+02:00I agree with Terry, here. As I posted elsewhere, ...I agree with Terry, here. As I posted elsewhere, the data seem to support the notion that the admixture event was pre-Toba. Following that, the admixed population became isolated in the extreme SE and would later become Papuan and Australian and part Oceanian. The remainder in South China and surrouindings, now reduced, simply saw their admixture diluted by continuing migrations East from the subcontinent - both along the coast (preserving more admixture all the way to Beringia and the Americas) and inland (Myanmar/adjacent China, and Southern Siberia - no admixture).<br /><br /><i>the more derived alleles the population shows the more modern it is</i><br /><br />The paper shows that in regions where modern humans have variation, and Denisovans carry the derived (non-Neanderthal, non-Chimpanzee) allele, we have about a 50% percent chance to also carry that allele - with extremely little variation across the globe. This indicates to me that modern humans split off the line (very roughly) about the same time when Denisovans and Neanderthal split (and subsequent mutations and admixture play a much smaller role).eurologisthttps://www.blogger.com/profile/03440019181278830033noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-91122419443818251802011-11-02T05:17:55.996+02:002011-11-02T05:17:55.996+02:00"Well IMO there are 2 possible scenarios"..."Well IMO there are 2 possible scenarios" <br /><br />Thetre is a third possibility: that the admixture actually occurred near where the Denisovan humans lived. The connecting link between that region and the islands beyond SE Asia has since been broken by the expansion of a non-Denisonva-admixed population. <br /><br />"This study reaffirms the fact of peculiar proximity of Amerindians to Neanderthals. On Fig. 1B one Amerindian sample is way out in the Neanderthal direction compared with the other populations. Table S3 shows that Amerindian populations (Colombian, Karitiana) rank right after Papuan, Melanesian and Yizu and ahead of many other East Asians in terms of frequencies of derived Denisovan alleles". <br /><br />Because, presumably, an element of the American population passed through the region of the Denisovans. But Native Americans also consist in part of non-admixed Northeast Asian populations.terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-85416696049324549722011-11-01T15:08:00.101+02:002011-11-01T15:08:00.101+02:00How to reconcile "population differentiation,...How to reconcile "population differentiation, genetic di- versity, and frequencies of derived alleles correlate with distance from Africa (1, 3, 34, 35), which is in line with anatomically modern human expansion out from Africa (3, 21)" with the data in Fig. 1B that shows that Africans are closer to chimpanzees, while non-Africans are closer to Denisovans and Neanderthals. Chimpanzees are less "modern" that Denisovans and Neanderthals, plus the more derived alleles the population shows the more modern it is.<br /><br />"East Asian (two-sided t test: P < 10−6) and Native American (P < 10−8) populations were found to be more similar to archaic hominins compared with European and Central/South Asian populations"<br /><br />This study reaffirms the fact of peculiar proximity of Amerindians to Neanderthals. On Fig. 1B one Amerindian sample is way out in the Neanderthal direction compared with the other populations. Table S3 shows that Amerindian populations (Colombian, Karitiana) rank right after Papuan, Melanesian and Yizu and ahead of many other East Asians in terms of frequencies of derived Denisovan alleles.<br /><br />This is a systemic phenomenon: basal X chromosome haplotype B006 detected in Neanderthals is most frequent in Amerindians, among modern human populations; Amerindians are high on blood group O and this is the blood group identified in two Neanderthal individuals; the genetically driven odontological feature, such as shovel-shaped incisors, are most frequent in Amerindians and they are highly frequent in Neanderthals and Asian Homo erectus.<br /><br />This is especially surprising because there're no archaic hominins in America, hence if the intensity of admixture is proportionate to the frequency of those shared alleles (as it's supposed to be), then we would expect to find the highest frequencies in Europe and East Asia, not in America and Oceania. Since America and Oceania harbor the greatest linguistic diversity on the planet - languages being the defining feature of behavioral modernity - these associations between "easternmost" non-Africans (Amerindians and Oceanians) and archaic hominins start looking like traces of common descent and not admixture. Africans, on the other hand, may have developed their close proximity to the chimps from homoplasies and through admixture with yet-to-be-identified local pre-modern hominins.German Dziebelhttps://www.blogger.com/profile/10703679732205862495noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-42838351924097504202011-11-01T13:54:21.771+02:002011-11-01T13:54:21.771+02:00Very interesting. Have a 'feeling' that i...Very interesting. Have a 'feeling' that in future further research will expand the 'universe' farther still and more genetic indicators will be found in our makeup from groups who survived the last glacial cycle 'out of Africa'.Pascvakshttps://www.blogger.com/profile/08311382875179534062noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-25524556236871796822011-11-01T04:40:21.564+02:002011-11-01T04:40:21.564+02:00This comment has been removed by the author.lkdjfhttps://www.blogger.com/profile/03514846090932680966noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-72262780959415338492011-11-01T01:22:52.375+02:002011-11-01T01:22:52.375+02:00Well IMO there are 2 possible scenarios:
1. The a...Well IMO there are 2 possible scenarios:<br /><br />1. The admixture event occurred in Island South East Asia, and admixed individuals are found principally there, with some also in surrounding areas via dispersal to Australia, the Philippines and parts of South East Asia mainland.<br /><br />2. The admixture event occurred in East Asia, and the present East Asian population arrived there more recently - like from the Americas, Beringia or Northern Asia someplace.pconroyhttps://www.blogger.com/profile/10312469574812832771noreply@blogger.com