科学家们通过最新的DNA片段发现，在人类的历史上同灵长类动物黑猩猩一样，男性的阴茎是有“刺”的。但是随着人类的不断进化，为了更好的促进大脑的发育，以及更长时间的性交，男性阴茎上的“刺”逐渐消失了。科学家们表示，这也有助于人类一夫一妻制的形成。

为了更精确的知晓人类的进化史，斯坦福桥大学的大卫-金斯利博士和他的团队一直致力于人类基因学的研究。在同其他灵长类动物进行对比后，他们发现了导致男性阴茎中的“刺”消失的基因片段。

金斯利博士说道：“很多人都会非常惊讶为什么其他雄性动物的阴茎中竟然长有刺，但实际上人类在进化中也是有的，不过部分基因的消失，使得人类的这些特征逐渐消失。”这项研究发表在《自然》杂志上，意在说明基因在控制物种的进化中扮演者极其重要的角色。

金斯利博士研究后发现与其他的灵长类动物想比，人类缺失了大约510种基因片段，其中这些基因片段包含控制大脑发育的基因和雄性激素分泌的基因。金斯利博士说道：“这些被删除的基因很多是为了更好的促进大脑的发展，而其中有部分基因就是关于‘刺’的，它的消失可以有助于人类进行更长时间的性交。”

“从某种程度上讲，阴茎中‘刺’的消失都是有助于人类进化的。水乳交融的性交能够产生更优质的后代，大脑也更为发达。”金斯利博士说道。不过，金斯利博士也发现了并不是所有基因的消失都是有利的，比如有些基因消失后人类更容易患上各种疾病，比如关节炎、癌症、疟疾、帕金森综合症等。他说道：“我们会逐渐揭开这些谜题。”

原文出处：

Nature   doi:10.1038/nature09774

Human-specific loss of regulatory DNA and the evolution of human-specific traits

Cory Y. McLean,1, 4 Philip L. Reno,2, 3, 4, 5 Alex A. Pollen,2, 4 Abraham I. Bassan,2 Terence D. Capellini,2 Catherine Guenther,2, 3 Vahan B. Indjeian,2, 3 Xinhong Lim,2 Douglas B. Menke,2, 3, 5 Bruce T. Schaar,2 Aaron M. Wenger,1 Gill Bejerano1, 2 & David M. Kingsley2, 3

Humans differ from other animals in many aspects of anatomy, physiology, and behaviour; however, the genotypic basis of most human-specific traits remains unknown1. Recent whole-genome comparisons have made it possible to identify genes with elevated rates of amino acid change or divergent expression in humans, and non-coding sequences with accelerated base pair changes2, 3, 4, 5. Regulatory alterations may be particularly likely to produce phenotypic effects while preserving viability, and are known to underlie interesting evolutionary differences in other species6, 7, 8. Here we identify molecular events particularly likely to produce significant regulatory changes in humans: complete deletion of sequences otherwise highly conserved between chimpanzees and other mammals. We confirm 510 such deletions in humans, which fall almost exclusively in non-coding regions and are enriched near genes involved in steroid hormone signalling and neural function. One deletion removes a sensory vibrissae and penile spine enhancer from the human androgen receptor (AR) gene, a molecular change correlated with anatomical loss of androgen-dependent sensory vibrissae and penile spines in the human lineage9, 10. Another deletion removes a forebrain subventricular zone enhancer near the tumour suppressor gene growth arrest and DNA-damage-inducible, gamma (GADD45G)11, 12, a loss correlated with expansion of specific brain regions in humans. Deletions of tissue-specific enhancers may thus accompany both loss and gain traits in the human lineage, and provide specific examples of the kinds of regulatory alterations6, 7, 8 and inactivation events13 long proposed to have an important role in human evolutionary divergence.