A comprehensive scan of the human genome finds that hundreds of our genes have undergone positive natural selection during the past 10,000 years of human evolution.

    Genes are the instructions organisms use to make proteins. They are encoded in genetic material, usually DNA, and some come in different versions, called “alleles." Positive natural selection occurs when one allele is favored over another due to changes in the environment.

    Researchers from the University of Chicago analyzed the genomes of 209 unrelated individuals from three distinct human populations: East Asians, Europeans and Yorubans from Nigeria. Each population contained roughly 250 positively selected genes; however, most of the affected genes differed depending on the group.

    “This study addresses the question 'Are humans still evolving?', and the answer is 'Absolutely,'" study team member Benjamin Voight said.

    The new study links genetic changes to major events in the history of our species.

    “There have been a lot of recent changes—the advent of agriculture, shifts in diet, new habitats, climatic changes—over the past 10,000 years," said Jonathan Pritchard, a human geneticist at the University of Chicago who led the study.

    The researchers also found positive selection in four pigment genes important for lighter skin in Europeans that were not known before. Scientists think humans evolved lighter skin in Europe as an adaptation to less sunlight.

    And in East Asians, they found strong evidence of positive selection in genes involved in the production of alcohol dehydrogenase (ADH), a protein necessary for breaking down alcohol. Many East Asians can't metabolize alcohol because they carry a mutation that prevents them from making ADH. The new finding suggests that the mutation may confer some currently unknown additional benefit.

    The study, which used data collected by the International HapMap Project, is detailed in the March 7 issue of the journal Public Library of Science-Biology.

    一次针对人类基因组的全面扫描显示：在过去的一万年中，人类体内上百组基因仍在经历积极的自然选择。

    基因是制造蛋白质的指导性有机体。它们藏于遗传物质中，一般在脱氧核糖核酸中，也有的在等位基因中。当一个等位基因比其他的更能适应环境时，积极的自然选择就会发生作用。

    芝加哥大学的研究人员从东亚人、欧洲人和尼日利亚的约鲁巴人这三种截然不同的人种身上提取基因并进行分析。每种人体内都含有大约250组被积极选择的基因；但是每种人基因进化的具体情况又是不同的。

    研究人员本杰明·沃埃特说：“这项研究让我们思考一个问题：人类还在进化吗？答案是：绝对在进化。”

    这项新研究让我们联想到人类历史上发生的重大事件。

    主研究员、芝加哥大学的人类遗传学专家乔纳森·皮查德说：“人类最近有很多进化现象：在过去一万年中，农业、饮食、栖息地、和气候都有很大变化。”

    研究人员还首次发现四种色素基因的进化对欧洲人至关重要。科学家认为欧洲人的肤色很浅的原因正是为了避免吸入过多的阳光。

    科学家在中东人体内的乙醇脱氢酶中也发现了积极选择的证据。这种酶能够快速瓦解酒精。很多中东人都有基因突变现象，导致不能产生乙醇脱氢酶。科学家相信这种突变也一定是为了适应某种环境而发生的。

    此项研究根据国际人类基因组单体型图计划提供的数据撰写而成，刊登在3月7日的生物科学公共图书馆杂志中。