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The impact of Neanderthal ancestry on human phenotypes
December 7, 2018 @ 12:00 pm - 1:00 pm PST
Graduate Research Fellow, University of California Los Angeles
Dec. 7, 12PM – 1PM
While multiple instances of admixture between archaic and modern humans have
now been documented, the biological consequences of these admixture events on
modern humans are not fully understood. We analyzed about 80,000 introgressed
Neanderthal alleles across 107 distinct phenotypes measured in up to 495,000
people of European ancestry in the UK Biobank dataset, taking advantage of more
than 6,000 single nucleotide polymorphisms (SNPs) that we specifically added to
the UK Biobank array prior to genotyping to study the impact of these Neanderthal
alleles. We discovered 1158 independent associations of introgressed Neanderthal
alleles with 75 phenotypes. We developed rigorous methodology to assess whether
Neanderthal ancestry is over- or underrepresented in modulating phenotypes
compared to random genetic variation, appropriately controlling for the frequencies
and allelic age distribution of such variants. We find that the contribution of
Neanderthal alleles to phenotypic variation is significantly depleted in the great
majority of the phenotypes examined which we show is consistent with the
observation that in general, Neanderthal mutations are on average older and that
natural selection has acted to remove Neanderthal mutations since introgression.
However, Neanderthal alleles were significantly overrepresented in contribution to
a handful of traits including male balding, chronotype, wheat intake, lung capacity,
and eye-related phenotypes. Most notably, we document directional selection for
Neanderthal-derived mutations that affect a number of traits including propensity
for baldness, later age of female puberty, high lung capacity, number of children,
alertness in the morning, and neuroticism. These analyses highlight aspects of
modern human biology that have been influenced by Neanderthal introgression
during the last fifty thousand years of non-African history when evidence for
symbolic behavior and innovation become evident in the archaeological record.
All are welcome.