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A new study in the journal Molecular Biology & Evolution analyzed the genomes of nearly 200 Inuits, looking particularly at TBX15/WARS2 alleles that affect body fat distribution. They compared these alleles to other people, as well as prehistoric populations like the Neanderthals and one Denisovan.

haplotypes-of-tbx15wars2

Figure 6. Network of archaic haplotypes and 20 most common present-day human haplotypes from the 1000 Genomes Project in the TBX15/WARS2 introgressed region as inferred by the HMM. Each pie chart is a haplotype, and the dots along each line represent the number of differences between each haplotype. The size of each pie chart is proportional to the log base 2 of the number of individuals in which that haplotype appears, and the colors refer to the proportion of those individuals that come from different continental populations. AFR: Africans. AMR: Americans. EAS: East Asians. EUR: Europeans. SAS: South Asians.

Their comparative analysis identified unique alleles within these loci that allows Inuits to have more brown fat, which burns and produces heat, unlike white fat. The particular forms of these genes are nearly unknown in Africa and relatively rare throughout Eurasia, but are very common in Inuits and other Native Americans.

The Denisovan analyzed had this gene variation too. Was this person the source of this change? Probably not since we only know of one Denisovan at this time. But it is an interesting find nonetheless because previous research strongly suggests humanity’s Denisovan inheritance includes a boosted immune system and alterations in skin color. The most dramatic example before now was the EPAS1 gene, which enables Tibetans to function at high altitudes and appears to have originated in our hominid cousins.

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