The lingering effects of Neanderthal introgression on human complex traits
- Cornell University, United States
- University of California, Los Angeles, United States
- Broad Institute, United States
- Harvard University, United States
- University of Southern California, United States
Abstract
The genetic variants introduced into the ancestors of modern humans from interbreeding with Neanderthals have been suggested to contribute an unexpected extent to complex human traits. However, testing this hypothesis has been challenging due to the idiosyncratic population genetic properties of introgressed variants. We developed rigorous methods to assess the contribution of introgressed Neanderthal variants to heritable trait variation relative to that of modern human variants. We applied these methods to analyze 235,592 introgressed Neanderthal variants and 96 distinct phenotypes measured in about 300,000 unrelated white British individuals in the UK Biobank. Introgressed Neanderthal variants have a significant contribution to trait variation consistent with the polygenic architecture of complex phenotypes (contributing 0.12% of heritable variation averaged across phenotypes). However, the contribution of introgressed variants tends to be significantly depleted relative to modern human variants matched for allele frequency and linkage disequilibrium (about 59% depletion on average), consistent with purifying selection on introgressed variants. Different from previous studies (McArthur 2021), we find no evidence for elevated heritability across the phenotypes examined. We identified 348 independent significant associations of introgressed Neanderthal variants with 64 phenotypes . Previous work (Skov 2020) has suggested that a majority of such associations are likely driven by statistical association with nearby modern human variants that are the true causal variants. We therefore developed a customized statistical fine-mapping methodology for introgressed variants that led us to identify 112 regions (at a false discovery proportion of 16%) across 47 phenotypes containing 4,303 unique genetic variants where introgressed variants are highly likely to have a phenotypic effect. Examination of these variants reveal their substantial impact on genes that are important for the immune system, development, and metabolism. Our results provide the first rigorous basis for understanding how Neanderthal introgression modulates complex trait variation in present-day humans.
Data availability
New software is deposited on GitHub: https://github.com/alipazokit/RHEmc-coeffData for figures (and supplement data) are deposited on GitHub: https://github.com/AprilWei001/NIM
Article and author information
Author details
Christopher R Robles
Sriram Sankararaman
Funding
National Institutes of Health (GM100233)
- David Reich
Alfred P. Sloan Foundation
- Sriram Sankararaman
Okawa Foundation
- Sriram Sankararaman
Burroughs Wellcome Fund
- Po-Ru Loh
Next Generation Fund at the Broad Institute of MIT and Harvard
- Po-Ru Loh
National Science Foundation (BCS1032255)
- David Reich
National Institutes of Health (HG006399)
- David Reich
Paul G. Allen Frontiers Group (Allen Discovery Center Grant on Brain Evolution)
- David Reich
John Templeton Foundation (61220)
- David Reich
Howard Hughes Medical Institute
- David Reich
National Institutes of Health (R35GM125055)
- Sriram Sankararaman
National Science Foundation (III1705121)
- Sriram Sankararaman
National Science Foundation (CAREER1943497)
- Sriram Sankararaman
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Wei et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 11,363
- views
-
- 863
- downloads
-
- 14
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
The lingering effects of Neanderthal introgression on human complex traits
eLife 12:e80757.
https://doi.org/10.7554/eLife.80757
Further reading
-
- Evolutionary Biology
- Genetics and Genomics
The evolutionary origins of Bilateria remain enigmatic. One of the more enduring proposals highlights similarities between a cnidarian-like planula larva and simple acoel-like flatworms. This idea is based in part on the view of the Xenacoelomorpha as an outgroup to all other bilaterians which are themselves designated the Nephrozoa (protostomes and deuterostomes). Genome data can provide important comparative data and help understand the evolution and biology of enigmatic species better. Here, we assemble and analyze the genome of the simple, marine xenacoelomorph Xenoturbella bocki, a key species for our understanding of early bilaterian evolution. Our highly contiguous genome assembly of X. bocki has a size of ~111 Mbp in 18 chromosome-like scaffolds, with repeat content and intron, exon, and intergenic space comparable to other bilaterian invertebrates. We find X. bocki to have a similar number of genes to other bilaterians and to have retained ancestral metazoan synteny. Key bilaterian signaling pathways are also largely complete and most bilaterian miRNAs are present. Overall, we conclude that X. bocki has a complex genome typical of bilaterians, which does not reflect the apparent simplicity of its body plan that has been so important to proposals that the Xenacoelomorpha are the simple sister group of the rest of the Bilateria.
-
- Evolutionary Biology
- Neuroscience
The diversity of cognitive skills across primates remains both a fascinating and a controversial issue. Recent comparative studies provided conflicting results regarding the contribution of social vs ecological constraints to the evolution of cognition. Here, we used an interdisciplinary approach combining comparative cognitive neurosciences and behavioral ecology. Using brain imaging data from 16 primate species, we measured the size of two prefrontal brain regions, the frontal pole (FP) and the dorso-lateral prefrontal cortex (DLPFC), respectively, involved in metacognition and working memory, and examined their relation to a combination of socio-ecological variables. The size of these prefrontal regions, as well as the whole brain, was best explained by three variables: body mass, daily traveled distance (an index of ecological constraints), and population density (an index of social constraints). The strong influence of ecological constraints on FP and DLPFC volumes suggests that both metacognition and working memory are critical for foraging in primates. Interestingly, FP volume was much more sensitive to social constraints than DLPFC volume, in line with laboratory studies showing an implication of FP in complex social interactions. Thus, our data highlights the relative weight of social vs ecological constraints on the evolution of specific prefrontal brain regions and their associated cognitive operations in primates.
