A tale of agriculturalists and hunter-gatherers: Exploring the thrifty genotype hypothesis in native South Americans.

Objectives: To determine genetic differences between agriculturalist and hunter-gatherer southern Native American populations for selected metabolism-related markers and to test whether Neel's thrifty genotype hypothesis (TGH) could explain the genetic patterns observed in these populations.
Materials and Methods: 375 Native South American individuals from 17 populations were genotyped using six markers (APOE rs429358 and rs7412; APOA2 rs5082; CD36 rs3211883; TCF7L2 rs11196205; and IGF2BP2 rs11705701). Additionally, APOE genotypes from 39 individuals were obtained from the literature. AMOVA, main effects, and gene-gene interaction tests were performed.
Results: We observed differences in allele distribution patterns between agriculturalists and hunter-gatherers for some markers. For instance, between-groups component of genetic variance (F _CT ) for APOE rs429358 showed strong differences in allelic distributions between hunter-gatherers and agriculturalists (p = 0.00196). Gene-gene interaction analysis indicated that the APOE E4/CD36 TT and APOE E4/IGF2BP2 A carrier combinations occur at a higher frequency in hunter-gatherers, but this combination is not replicated in archaic (Neanderthal and Denisovan) and ancient (Anzick, Saqqaq, Ust-Ishim, Mal'ta) hunter-gatherer individuals.
Discussion: A complex scenario explains the observed frequencies of the tested markers in hunter-gatherers. Different factors, such as pleotropic alleles, rainforest selective pressures, and population dynamics, may be collectively shaping the observed genetic patterns. We conclude that although TGH seems a plausible hypothesis to explain part of the data, other factors may be important in our tested populations.
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