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"Lola" reconstructed from birch "gum", blue eyes and dark skin.
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[QUOTE]Originally posted by the lioness,: [QB] [IMG]https://farm1.static.flickr.com/28/359663597_e295116dec_o.jpg[/IMG] ______________________________________________ https://arxiv.org/ftp/arxiv/papers/1512/1512.09115.pdf [b]Expanded Distance-based Phylogenetic Analyses ofFossilHomoSkull Shape Evolution[/b] Peter J. Waddell1 . [b]There is the interesting pattern for both the Gravettian and the pre-Gravettian skulls thatthe female skulls tend to fall very close to, or even within, the diversity marked out by the two Khoisan skulls. [/b] [b]Trinkaus (2007) argues persuasively that the European forms show features that could have been derived from Neanderthals,[/b] while some recent sequence data suggests that in at least one case, this is confirmed (on an Oase specimen, Fuet al. 2015). Here, the extent to which archaic interbreeding might have altered the general form of the skulls from these populations is further assessed. Also assessed for the first time with a quantitative evolutionary model will be the relative extent of archaic genes in these four distinct populations, and a discussion of what might have happened later, potential via the agencies of natural selection. Discussion The current analyses provide strong support for the results of Waddell et al. (2014). Forexample, the enigmatic Iwo Eleru skull is seen to with 100% confidence to locate in a part of the tree well outside the range of modern human variation, and with one exception (UC1), amongst a range of middle Pleistocene African archaic forms. One exception to reinforcing the results in Waddell (2014) is a local rearrangement of the position of Iwo Eleru. However, while Iwo Eleru now locates most often sister to LH18, the hypothesis that it represents a preceding lineage cannot be excluded. Schwartz and Tattersall (2005) give a very useful summary of the morphological forms(morphs) at different sites and times. For the African forms at about 2 to 1.5 mya they describe multiple distinct forms which cross the traditional Homo habillis/Homo erectus/Homo ergaster lines. Represented here are the 3733 and a 3883/3732 morphs, which are described as quite distinct on discrete morphological features. Here, the shape of the major sutures and boundaries of the skull cap are compared. [b]The difference between these two morphs in terms of shape of the skull cap is quite comparable in magnitude to the difference seen between two Neanderthals or between two modern Khoisan, for example.[/b] In this sense they do not strongly contrast. However,in terms of shape distance-based phylogenetic analyses, this is not that unusual, in that much ofthe material of this period and often lumped (Lordkipanidze et al. 2013) under the title Homo erectus from all around the world has broadly similar shape, despite some appreciable size differences (e.g. brain size varying by a factor of two), as well as huge geographical and temporal differences. To this, Schwartz and Tattersall (2005) would argue also major differences indiscrete qualitative morphological features. Indeed there is quite a controversy based largely on interpretations of non-evolutionary shape analyses (e.g., Schwartz et al. 2013, Spoor 2013,Bermúdez de Castro et al. 2014, Waddell 2014). Taken together, this suggests some conservatism of basic skull cap shape for this diverse assemblage, and a correspondingly worse signal to noise ratio in the data. This conservatism in overall skull cap shape change accelerated with the middle Pleistocene and accelerated again with the African lineage leading to Homo sapiens(Waddell2014). It may also explain why non-evolutionary assessments of 3D geometric morphometric upper skull shape data are failing to identify distinct assemblages in a huge range of Homospecimens.The sister group relationship of Petralona and SH5 is surprisingly strong in the analyses presented here, and is not predicted by the lists of morphological features considered by Schwartz and Tattersall (2005). However, they do conclude that what they consider an endemic European lineage ofSH5, Neanderthals and allies is probably linked to some of the forms commonly called Homo heidelbergensis. Perhaps is is no coincidence that of all the Homo heidelbergensis-like things in this analysis, SH5 and Petralona, the only two European forms, are bracketed by Neanderthals, and at the more extreme values of q with P also adjusted, they form a clade with Dali, the other Eurasian “Homoheidelbergensis” within a large group of Neanderthals. This is on marked contrast to the two mostprominently cited proposed African Homo heidelbergensis skull caps, Kabwe and Saldahna, which consistently fall well away from Neanderthals. Indeed, the positions of these two taxa on the tree is in contrast both with the Eurasian Homo heidelbergensis specimens and between themselves. That is,always deepest diverging on the tree, for Kabwe, and always near the root of the African lineage persisting after the divergence of Neanderthals and heading to modern humans, for Saldahna. The residual resampling results supporting such distinct positions was nearly always 100%. This is all more evidence that Homo heidelbergensis is probably not a clade, but has members scattered on at least three and possibly four major lineages in the tree ofHomo (the last being achieved with the data used here when LH18 is described as a member of Homo heidelbergensis, Magori and Day 1983).[b]In these all analyses, the first well defined anatomically modern human, Qafzeh 9,consistently falls within the diversity marked out by the male and female Khoisan skulls.[/b] Thus giving it the title of the “Skull of Eve” is less of stretch than calling the ancestor of our mitochondrial DNA Waddell (2015). Expanded Phylogenetic Analyses of 3D Homo Skull Evolution Page 17 “Eve” (e.g., Penny et al. 1995, Waddell and Penny 1996). While Qafzeh9 is very modern in overall cranial shape, it does exhibit some characteristics that suggest it too may be part of a hybrid population (between modern or near modern humans and Middle Eastern Neanderthals). This includes a planum alveolare on the mandible, which is a pleisiomorphic trait which Trinkaus (2007) sees as introgressed from Neanderthals into early europeans also. Importantly, the fully modern shape of the upper skull of Qafzeh 9, as well as of many early Europeans, would seem to convincingly deflate the often heard argument that earlier modern humans only look more archaic due to life style or climate(at least as regards upper skull shape). It seems the favored hypothesis now must be that if a skull looks decidedly archaic, then archaic genetic factors are the leading explanation.These phylogenetic analyses also reveal a trend for large brained males in probable hybrid populations including pre-Gravettians, Gravettians, the Upper Cave and Qafzeh/Skhul specimens to show markedly more archaic skull shapes. This may simply be a sex assignment bias, but more interestingly, it might also be due to how archaic X chromosomes in a hybrid context are imprinted and guide brain development (e.g., Lepage et al. 2013). This trend is not seen in Neanderthals or in recent modern human populations, making its biological reality seem more likely. The overall result of these analyses is to suggest that the extent of archaic genes was Gravettian, pre-Gravettian,Qafzeh/Skhul and Upper Cave China, in order of increasing archaic content.There has been much discussion of how much and what archaic genes in modern humans means for the biology Homo sapiens(e.g. Krause et al. 2010, Reich et al. 2010, Waddell et al. 2011,Waddell 2013 Fu et al. 2015). To date analyses only reveal a few percent of archaic genes in the bulk of modern humans, with some small and localized populations such as Papuans and Australian Aborigines showing perhaps 10% of such genes across the genome from multiple sources (Reich etal. 2011, Waddell et al. 2011, 2013). However qualitative results such as those of Trinkaus (2007) and now the quantitative evolutionary analyses of this article show that early populations of near anatomically modern and even behaviorally fully modern humans appear to have incorporated a markedly higher percentage of archaic genes. Despite occupying vast areas such as Europe and China,most of this archaic genetic contribution appears to have died out, just as the archaics themselves did(or were died out). The ultimate reason for that remains unknown, although the mechanism in large areas such as Europe and China includes the wholesale replacement of earlier populations by agriculturalists. The question then becomes, why did these later highly successful populations not incorporate high percentages of archaic genes when the original modern occupants of the land had them in greater abundance? A leading hypothesis must be that the same coordinated gene complexes that made the ancestors of the crown group Homo sapiens such an irresistible force may well have again asserted themselves in the processes leading to the rise of the first really successful post hunter gather societies. How much of a role natural selection might have played in these contexts remains to be seen, yet the role for natural selection weeding out much of the legacy of archaic interbreeding cannot be dismissed. [/QB][/QUOTE]
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