Bioinformatics Research Centre, Aarhus University, Aarhus C, Denmark.
Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
Nat Commun. 2021 Sep 7;12(1):5317. doi: 10.1038/s41467-021-25524-4.
After the main Out-of-Africa event, humans interbred with Neanderthals leaving 1-2% of Neanderthal DNA scattered in small fragments in all non-African genomes today. Here we investigate what can be learned about human demographic processes from the size distribution of these fragments. We observe differences in fragment length across Eurasia with 12% longer fragments in East Asians than West Eurasians. Comparisons between extant populations with ancient samples show that these differences are caused by different rates of decay in length by recombination since the Neanderthal admixture. In concordance, we observe a strong correlation between the average fragment length and the mutation accumulation, similar to what is expected by changing the ages at reproduction as estimated from trio studies. Altogether, our results suggest differences in the generation interval across Eurasia, by up 10-20%, over the past 40,000 years. We use sex-specific mutation signatures to infer whether these changes were driven by shifts in either male or female age at reproduction, or both. We also find that previously reported variation in the mutational spectrum may be largely explained by changes to the generation interval. We conclude that Neanderthal fragment lengths provide unique insight into differences among human populations over recent history.
主要的非洲走出事件之后，人类与尼安德特人杂交，导致今天所有非非洲人类基因组中都散布着 1-2%的尼安德特人 DNA 小片段。在这里，我们研究了从这些片段的大小分布中可以了解到哪些关于人类人口过程的信息。我们观察到欧亚大陆的片段长度存在差异，东亚人的片段比西欧亚人的长 12%。与现存人群与古代样本的比较表明，这些差异是由于自尼安德特人混合以来，重组导致的长度衰减率不同造成的。一致地，我们观察到平均片段长度与突变积累之间存在很强的相关性，类似于从三人研究中估计的生育年龄变化所预期的那样。总的来说，我们的结果表明，在过去的 4 万年中，欧亚大陆的生育间隔存在差异，最多可达 10-20%。我们使用性别特异性突变特征来推断这些变化是由生育年龄的男性或女性变化驱动的，还是两者都有。我们还发现，先前报道的突变谱的变化可能在很大程度上可以用生育间隔的变化来解释。我们得出结论，尼安德特人片段长度为我们提供了对人类种群在最近历史中的差异的独特见解。
