DNA差异研究显示，在人类的历史长河里，少数的男性似乎比其他人在基因池里有着更多的遗传表现。
由亚利桑那大学人口遗传学家Michael Hammer领导的一个研究小组，对分属6组的90人进行了DNA测序，这些人分别为：美拉尼西亚人（Melanesians），巴斯克人（Basques），汉族人，三组非洲居民——Mandenka，Biaka和San 。结果发现，X染色体上有较多的基因差异，如果人类历史中相同数量的男性和女性组成配偶的话，X染色体的差异不会有那么大。Hammer说，“大多数社会实现某种形式一夫多妻或一妻多夫”。即使现代西方的男性只有一个妻子，但他们仍然想和更多女性生孩子，这种愿望比女性至于男性强烈的多。研究显示，现代的一夫一妻制甚至还没有在我们基因中留下标记。Hamme说，“我不知道一夫一妻制实施了多久，但从进化上看不是很突出。”
论文发表在开放获取杂志《公共科学图书馆·遗传学》（PLoS Genetics）上。（生物谷Bioon.com）
生物谷推荐原始出处：
PLoS Genetics，4(9): e1000202. doi:10.1371/journal.pgen.1000202，Michael F. Hammer, Jeffrey D. Wall
Sex-Biased Evolutionary Forces Shape Genomic Patterns of Human Diversity
Michael F. Hammer1,2*, Fernando L. Mendez2, Murray P. Cox1, August E. Woerner1, Jeffrey D. Wall3
Comparisons of levels of variability on the autosomes and X chromosome can be used to test hypotheses about factors influencing patterns of genomic variation. While a tremendous amount of nucleotide sequence data from across the genome is now available for multiple human populations, there has been no systematic effort to examine relative levels of neutral polymorphism on the X chromosome versus autosomes. We analyzed ~210 kb of DNA sequencing data representing 40 independent noncoding regions on the autosomes and X chromosome from each of 90 humans from six geographically diverse populations. We correct for differences in mutation rates between males and females by considering the ratio of within-human diversity to human-orangutan divergence. We find that relative levels of genetic variation are higher than expected on the X chromosome in all six human populations. We test a number of alternative hypotheses to explain the excess polymorphism on the X chromosome, including models of background selection, changes in population size, and sex-specific migration in a structured population. While each of these processes may have a small effect on the relative ratio of X-linked to autosomal diversity, our results point to a systematic difference between the sexes in the variance in reproductive success; namely, the widespread effects of polygyny in human populations. We conclude that factors leading to a lower male versus female effective population size must be considered as important demographic variables in efforts to construct models of human demographic history and for understanding the forces shaping patterns of human genomic variability.
