The Scent of a Man



If you have ever been attracted by a person's scent, it may be their genes you smell. Researchers believe that women can identify men based on differences as small as a single gene.



In the most recent issue of Nature Genetics scientists look at the link between women's preference for the odors men give off and a group of genes called the Major Histocompatibility Complex (MHC) - which are an important part of the body's immune response.

闻味识男人



如果你曾经被某人的气味所吸引，实际上你闻到的是他们的基因。研究人员认为，女人能在一个单基因的基础上辨别男人之间的差别。 女人根据小到单基因的差别就能辨别男人的不同。



在最新出版的一期《自然遗传学》杂志上，科学家阐述了女性对男性发出气味的喜爱与主要组织相容性复合体（MHC）这组基因之间的关系。MHC是人体免疫系统反应的重要组成部分。



A group of 49 women were asked to smell 10 boxes which contained pieces of T-shirts that had either been worn by men or contained a familiar household odor such as bleach or clove.

The men who had worn the T-shirts were selected based on their MHC genes, and were told to sleep in the shirt for two consecutive nights while avoiding other scents entirely, such as colognes and even contact with other people.



The women were then asked to rate each scent based on their familiarity, intensity, pleasantness, and spiciness, as well as choose the one odor which they would choose if they had to smell it all the time.

让受试组的49位女士闻装有男人穿过的衬衫或含有家常气味如剂味或丁香味的10个盒子。





提供自己穿过衬衫的男子是按他们MHC基因选出来的，他们连续两夜都穿着这件衬衫睡觉，其间完全避开其它气味，如古隆香水，甚至不与其它人接触。



然后，要求女士们依据自己熟悉、强烈、愉悦和馨香的感受，将闻过的气味分类，并从中挑一种她们终身都能够接受的气味。



"A clear pattern emerged," said Dr. Carole Ober, co-author of the study and a geneticist at the University of Chicago. "The women did not choose scents of men with genes totally similar to their own, or totally dissimilar to their own. They chose men with an intermediate level of difference."



"The real surprising thing is that there was something special about paternally from one's father inherited genes," said Wayne Potts, an expert in the area of MHC research at the University of Utah.



Moreover, the women showed no preference for odors from men with the same gene types as their mothers, but did show a preference for odors from men who shared genes they inherited from their fathers.

"一种清晰的分类模式出现了，"该项研究的合作者，芝加哥大学的遗传学家Carole Ober博士说。他说："受试女士没有选择基因完全与自己相似或相异男人的气味，而是选择了有适度差别的男人气味。"

犹他大学专门研究MHC的专家Wayne Potts说："真正令人惊奇的是该研究结果与父系遗传基因有特殊关系。"



受试女士不喜欢与自己母亲有相同基因类型的男士气味，但却偏爱具有与她们从父亲身上遗传而得基因的男人气味。



Experts believe there are two major reasons for preferring a mate with different genes than your own. The first is that parents with more diverse MHC genes will give rise to offspring with better immune systems, and the second is that by avoiding mates who have very similar MHC types, you also avoid inbreeding.

In fact, previous studies have shown that married people tend to have different types of genes than their spouse.



At the same time, however, the propensity to choose someone with slightly similar genes can also avoid the problem of outbreeding - the mixing of genes that are too different.

专家认为，人类爱选与自己基因相异的人为配偶的主要原因有两点，一是具有较大差异MHC基因的父母生出的后代具有较好的免疫系统，其次是避免配偶有非常相似的MHC基因型，这样可以避免近亲繁殖。

事实上，以前的研究也表明已婚的人趋向于与配偶有不同的基因。



　



然而，与此同时，选择稍微相似基因的人为配偶也能避免远系繁殖___差异太大的基因组合问题。



"The best is in the middle range and no one knew that before," said Martha McClintock, co-author of the study and a professor of psychology at the University of Chicago，"Everybody always says different is better, well you get different, different, different, and then it becomes a point where it's no longer better."

Potts cautions that choosing an odor from within a box may not represent what actually happens in the real world when women are attracted to their mates.



"It's the wrong emphasis to say that this means that they're going to prefer MHC similar males when it comes to mating," said Potts. "There is other social context."

该项研究的合作者，芝加哥大学的心理学教授Martha McClintock说："适度遗传差异是最好的，以前没有人知道这个道理。人人都说有差异比较好，你可能得到这样那样的遗传差异，然后，差异大到某一程度时就不再好了。

Potts提醒说，从盒子中选闻气味不能代表现实生活中女性被男子身上散发气味所吸引的实际过程。



Potts说："以此证明女性喜欢选择MHC基因相似的男人做配偶是错的，因为选择配偶还有其它的社会内容。"



"That is one of the molecular missing links," said Potts. "We don't know exactly what the odorants are."

Potts explains that one hypothesis is linked to the ability of MHC molecules to stick to very specific pieces of protein in cells. These MHC molecules and the proteins stuck to them are what is believed to be detected as an odor.



Whatever the mechanism, this study disproves the assumption that humans have a poorly developed sense of smell. ABCNEWS

Potts说: "这儿有一个分子连接错位，但我们不知道专管发出味道的遗传基因的确切位置。"

Potts解释说，一种假设是与MHC分子粘到细胞内特定蛋白质的能力有关，据称，就是这些MHC分子和粘在上面的蛋白质发出了可闻到的味道。



无论该研究的机理如何，该研究至少推翻了有关人类嗅觉发育不良的假设。美国广播
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