人类长期以来一直受定向选择塑造，但过去的方法受限于古DNA样本稀少且常受损，以及随机漂变和群体混合等因素的混杂，难以在时序上区分适应性变异与非适应性扩散。哈佛大学的 Ali Akbari 与 David Reich 团队建立了统计工具箱，通过古DNA样本之间的成对比较识别定向选择特征。
该工具应用于 15,836 名西亚欧血缘古代个体和 6,438 名现代人，时间跨度覆盖 18,000 年，并加入 10,016 个新古基因组；这使全球古DNA样本池翻倍，并较以往自然选择研究提高了 14 倍样本规模。此前在同一 11,000 年窗口仅记录到 21 例定向选择，而新研究识别出 479 个高度可能由自然选择驱动的基因变体，显示近期西亚欧地区定向选择并不罕见。
研究发现一个与病原识别相关且现今约每五人一人出现的遗传信号，在约 4,000 年前以前几乎缺失，说明其出现未必由早于此的农业扩展直接驱动；与囊性纤维化风险相关、曾被假设因霍乱耐受而受益的基因，在霍乱曾流行的时期未见选择证据。研究还识别出 44 个跨基因组群体的定向选择信号，并显示与2型糖尿病、精神分裂症和双相障碍相关基因总体受负向选择，且这种选择强度在约 11,700 年前始于全新世后明显增强。
Humans have long been shaped by directional selection, but historical methods were limited by small, often degraded ancient-DNA samples and confounding drift or migration effects, making it difficult to separate adaptive change from nonadaptive spread. A team at Harvard led by Ali Akbari and David Reich built a statistical toolkit that detects directional-selection signatures via pairwise comparisons across ancient-DNA collections.
They applied it to 15,836 ancient individuals of West Eurasian ancestry plus 6,438 modern humans, spanning 18,000 years and adding 10,016 new ancient genomes; this doubled global ancient-DNA resources and increased sample size 14-fold over prior selection studies. Over the same 11,000-year window, earlier work reported only 21 directional-selection cases, while the new analysis found 479 variants highly likely to have been selected, indicating selection was far more widespread in recent millennia.
One pathogen-recognition-associated variant now found in roughly one in five modern samples was nearly absent before about 4,000 years ago, arguing against a simple link to much earlier agricultural expansion. Variants once hypothesized to rise because of cholera resistance in cystic fibrosis carriers showed no selection signal during West Eurasian cholera endemic periods, while 44 broader gene-group signatures were found, including negative selection on genes tied to type 2 diabetes, schizophrenia, and bipolar disorder, with intensity strengthening sharply from about 11,700 years ago in the Holocene.
Source: How natural selection really shaped humanity
Subtitle: Adaptation in response to evolutionary pressure is surprisingly commo
Dateline: 4月 16, 2026 05:31 上午