科研人员此前已发现，现代人基因组中的少量基因来自尼安德特人。然而，9月12日刊登在美国新一期《国家科学院学报》（PNAS）上的一项研究表明，二者之间的基因交换并不常见。
尼安德特人是远古分布在欧洲大陆的最主要古人类，是与现代人在进化学上最近的亲族。迄今，有关尼安德特人的最早遗迹出现在距今约40万年前，其分布遍及欧洲和西亚。距今约3万年前，尼安德特人逐渐灭绝，进而被现代人的祖先取而代之。
瑞士日内瓦大学和伯尔尼大学的研究人员利用计算机模型，模拟了现代人自5万年前从非洲东北部扩张以来同尼安德特人之间的可能联系。通过比对现代法国人和中国人的DNA样本，他们发现在大多数情况下，尼安德特人和现代人祖先之间杂交繁殖的成功率很可能不到2%，因此基因交换也非常有限。
研究人员说：“由于这种杂交后代的健康状况非常差……两个物种之间的基因交流存在极强的障碍。”
一个国际研究人员团队去年5月曾在美国《科学》杂志上报告说，尼安德特人的基因组测序工作已经完成，他们将测序结果与来自世界5个地区的现代人基因组比较后发现，现代人的祖先与尼安德特人非常可能在小范围内发生过杂交。
英文原文摘要：
trong reproductive isolation between humans and Neanderthals inferred from observed patterns of introgression
Currat, Mathias; Excoffier, Laurent
Recent studies have revealed that 2–3% of the genome of non-Africans might come from Neanderthals, suggesting a more complex scenario of modern human evolution than previously anticipated. In this paper, we use a model of admixture during a spatial expansion to study the hybridization of Neanderthals with modern humans during their spread out of Africa. We find that observed low levels of Neanderthal ancestry in Eurasians are compatible with a very low rate of interbreeding (<2%), potentially attributable to a very strong avoidance of interspecific matings, a low fitness of hybrids, or both. These results suggesting the presence of very effective barriers to gene flow between the two species are robust to uncertainties about the exact demography of the Paleolithic populations, and they are also found to be compatible with the observed lack of mtDNA introgression. Our model additionally suggests that similarly low levels of introgression in Europe and Asia may result from distinct admixture events having occurred beyond the Middle East, after the split of Europeans and Asians. This hypothesis could be tested because it predicts that different components of Neanderthal ancestry should be present in Europeans and in Asians.
