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[QUOTE]Originally posted by DD'eDeN: [QB] Rapid Evolution of Lighter Skin Pigmentation in Southern Africa BRENNA M. HENN1 , MENG LIN1 , ALICIA R. MARTIN2 and REBECCA SIFORD1 1 Ecology and Evolution, Stony Brook University, 2 Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston Skin pigmentation is under strong directional selection for reduced melanin density in northern European and Asian populations. Conversely, dark pigmentation is thought to be under stabilizing selection in equatorial populations exposed to intense ultraviolet radiation. We high-throughput sequenced pigmentation genes in over 400 indi- viduals from South Africa and demonstrate that a canonical skin pigmentation gene, SLC24A5, experienced recent adaptive evolution in the KhoeSan populations of far southern Africa. The functionally caustive allele lightens basal skin pigmentation by 4 melanin units, explaining 11.9% variance in pigmentation in these popu- lations. Haplotype analysis and demographic models indicate that the allele was introduced into the KhoeSan only within the past 3,000 years likely by eastern African pastoralists. The most common haplotype is shared among the KhoeSan, eastern Africans and Europeans but has risen to a frequency of 25%, far greater than expected given initial gene flow. The SLC24A5 locus is a rare example of strong, ongoing adap- tation in very recent human history. The complicated genetic landscape of skin color in India FLORIN MIRCEA ILIESCU1 , GEORGE CHAPLIN2 , NIRAJ RAI3 , GUY JACOBS1 , CHANDANA BASU MALLICK4,5, ANSHUMAN MISHRA3 , RIE GOTO1 , RAKESH TAMANG3 , GYANESHWER CHAUBEY4 , IRENE GALLEGO ROMERO6 , FEDERICA CRIVELLARO7 , RAMASAMY PITCHAPPAN8 , LALJI SINGH3 , MARTA MIRAZON-LAHR7 , MAIT METSPALU4,5, KUMARASAMY THANGARAJ3 , TOOMAS KIVISILD1,4,5 and NINA G. JABLONSKI2 1 Archaeology and Anthropology, University of Cambridge, 2 Anthropology, The Pennsylvania State University, 3 CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 4 Estonian Biocentre, Tartu, 5 Department of Evolutionary Biology, University of Tartu, 6 School of Biological Sciences, Nanyang Technological University, 7 Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, 8 Chettinad Academy of Research and Education, Chettinad Health City Human skin color represents a classic example of a quantitative trait that is highly polymorphic in humans. Models based on natural selection suggest that pigmentation variation has accu- mulated in response to human dispersals and colonization of diverse environments, primarily due to differences in the damaging versus vitamin D synthesis-related effects of UV radiation (UVR) at different latitudes. Indian populations, despite being spread across a relatively narrow latitudinal range, show a high level of variation in skin color phenotype. Using recorded Melanin Index (MI) data from populations throughout the subcon- tinent we previously suggested the presence of phenotypic “overprinting” due to successive popu- lation migrations and the action of both natural and sexual selection forces. We now show that, in the context of pronounced endogamy, the role of the SLC24A5 functional polymorphism on skin color variation in India is variable on a popula- tion dependent basis. The presence of epistasis between skin color genes in studied popula- tions leads to some individuals homozygous for the SLC24A5 European allele having highly melanized skin; hence, the skin lightening effect of the rs1426654-A allele is overridden by the action of novel variants within skin color genes. Finally, considering the migration patterns and the variable social selection forces at play across India, we tested the correlation between the skin color dimorphism observed within some Indian populations and genetic variation patterns. These results thus further illustrate the complex genetic landscape of skin color around the world and warrant caution when predicting color pheno- types from ancient DNA studies. --- Can Small be All? The Limited Commonalities of Mata Menge and Liang Bua Hominins on Flores MACIEJ HENNEBERG1 , ADAM J. KUPERAVAGE2 , SAKDAPONG CHAVANAVES3 and ROBERT B. ECKHARDT3 1 Adelaie Medical School, The University of Adelaide, 2 Department of Public and Allied Health Sciences, Delaware State University, 3 Laboratory for the Comparative Study of Morphology, Mechanics, and Molecules Department of Kinesiology, Pennsylvania State University The original diagnosis of “Homo floresiensis” from the Liang Bua skeletal remains listed among numerous others these defining elements: Small- bodied; endocranial volume similar to, or smaller than, Australopithecus africanus; lacks masti- catory adaptations present in Australopithecus and Paranthropus; first and second molar teeth of similar size; mandibular coronoid process higher than condyle; mandible without chin. We already have shown in 2015 that these and many additional defining elements largely are those of the LB1 individual, since most LB specimens are represented by only one or two bones each. Even some of the few duplicated elements differ: The LB6 mandibular ramus is shorter than that of LB1 and lacks a coronoid higher than condyloid process. Statures originally were under-estimated and are matched in regional extant small bodied humans, as are small, chinless mandibles. The Mata Menge (0.7 Ma) gnathic specimens include a fragment of mandibular corpus (SOA-MM 4) plus six teeth. These establish little other than small size within the already known human range. For example, SOA-MM1 shows uncor- rected dimensions of 9.7 mm MD x 8.9 mm BL, close to Klasies River Mouth KRM14624 (9.3x8.8) and KRM43110 (10.2x9.1). Given the extremely limited Flores skeletal evidence, and the known unreliable correlations of body and brain size with tooth sizes, it is premature to suggest that the Mata Menge gnathic fragments establish any more than previously known archaeological evidence: the existence of hominins of as yet indeterminable taxonomic status on an island where Homo sapiens is known to have a living and archeological presence. DD ~ David ~ Da'ud ~ Diode ~ ∆^¥°∆ [/QB][/QUOTE]
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