Institut de Biologia Evolutiva (CSIC-UPF), Department de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain.
Mol Biol Evol. 2011 Feb;28(2):1099-110. doi: 10.1093/molbev/msq294. Epub 2010 Nov 1.
Pygmy populations are among the few hunter-gatherers currently living in sub-Saharan Africa and are mainly represented by two groups, Eastern and Western, according to their current geographical distribution. They are scattered across the Central African belt and surrounded by Bantu-speaking farmers, with whom they have complex social and economic interactions. To investigate the demographic history of Pygmy groups, a population approach was applied to the analysis of 205 complete mitochondrial DNA (mtDNA) sequences from ten central African populations. No sharing of maternal lineages was observed between the two Pygmy groups, with haplogroup L1c being characteristic of the Western group but most of Eastern Pygmy lineages falling into subclades of L0a, L2a, and L5. Demographic inferences based on Bayesian coalescent simulations point to an early split among the maternal ancestors of Pygmies and those of Bantu-speaking farmers (∼ 70,000 years ago [ya]). Evidence for population growth in the ancestors of Bantu-speaking farmers has been observed, starting ∼ 65,000 ya, well before the diffusion of Bantu languages. Subsequently, the effective population size of the ancestors of Pygmies remained constant over time and ∼ 27,000 ya, coincident with the Last Glacial Maximum, Eastern and Western Pygmies diverged, with evidence of subsequent migration only among the Western group and the Bantu-speaking farmers. Western Pygmies show signs of a recent bottleneck 4,000-650 ya, coincident with the diffusion of Bantu languages, whereas Eastern Pygmies seem to have experienced a more ancient decrease in population size (20,000-4,000 ya). In conclusion, the results of this first attempt at analyzing complete mtDNA sequences at the population level in sub-Saharan Africa not only support previous findings but also offer new insights into the demographic history of Pygmy populations, shedding new light on the ancient peopling of the African continent.
俾格米人群体是目前生活在撒哈拉以南非洲的少数狩猎采集者之一，根据他们目前的地理位置，主要分为东部和西部两个群体。他们分布在中非地带，周围是说班图语的农民，与他们有着复杂的社会和经济互动。为了研究俾格米人群体的人口历史，采用群体方法对来自中非十个群体的 205 个完整线粒体 DNA（mtDNA）序列进行了分析。两个俾格米群体之间没有母系谱系的共享，西部群体的特征是单倍群 L1c，而大多数东部俾格米谱系则属于 L0a、L2a 和 L5 的亚群。基于贝叶斯凝聚模拟的人口推断表明，俾格米人和说班图语的农民的母系祖先在早期就已经分开（约 7 万年前）。在班图语扩散之前，已经观察到说班图语的农民的祖先出现了人口增长的证据，开始于约 6.5 万年前。随后，说班图语的农民的祖先的有效人口规模保持不变，直到约 2.7 万年前，与末次冰期最大值相吻合，此时东部和西部俾格米人开始分化，只有西部俾格米人和说班图语的农民之间有随后的迁移证据。西部俾格米人在 4000-6500 年前有近期瓶颈的迹象，与班图语的扩散相吻合，而东部俾格米人似乎经历了更古老的人口减少（2 万-4 千年前）。总之，这是首次在撒哈拉以南非洲进行的群体水平上分析完整 mtDNA 序列的尝试，不仅支持了先前的发现，还为俾格米人群体的人口历史提供了新的见解，为非洲大陆的古老人口迁徙提供了新的线索。
