生儿子的副作用

生儿子的副作用 千百年来一直在抱怨儿子会让自己操心死的母亲们也许是对的——发在 《科学》杂志上的一篇论文显示生男孩会缩短妇女的寿命。土尔库(芬兰西南部 港市)大学的进化生物学家萨缪尔?赫勒和他的同事们发现，平均每生一个儿子 会使女人短寿34个星期。另一方面，生女孩会延长女人的寿命，不过幅度非常 小。赫勒和他的同事研究了1640至1870年间拉普人的婚姻及生育记录。他们写 道:“我们的研究结果表明，跟生养女儿相比，生儿子会给母亲带来较高的相对 长期存活成本。”这里面也可能有生物学上的原因。研究表明生儿子在生理上有 更大的难度——他们在子宫里长得更大也更快，一些研究显示妇女生了儿子以后 再次怀孕所需的时间要比生女儿以后长。(男性)胎儿产生的睾丸激素会抑制母 亲的免疫系统，这可能会使她更容易感染疾病。赫勒说，与其芬兰和瑞典邻居都 大不相同的拉普人族群本身可能有遗传上或是社会文化上的差别。但他并不这样 看。“没有理由认为只有拉普人当中才有这种效应，”他说。“一般来说，到处 乱跑的男孩更让母亲操心，而女孩更愿意帮助母亲。” Those Boys Really Will Be the Death of You, Mom Mothers who have complained through the centuries that their sons will be the death of them may be right ?nbsp;a study published in the journal Science shows having boys shortens a woman's life span. Each son takes an average of 34 weeks off a woman's life span, evolutionary biologist Samuli Helle and colleagues at the University of Turku found. On the other hand, having daughters adds, but only very slightly, to a woman's life span. Helle and colleagues looked at birth and marriage records of Sami* people from 1640 to 1870. "Our results suggest that giving birth to sons had a higher relative long-term survival cost for mothers than giving birth to and raising daughters," they wrote. There could be biological reasons for this. Studies show boys are physiologically more demanding to produce ---they grow bigger and faster in the womb, and some studies show it takes a woman longer to get pregnant again after having a son than after having a daughter. Testosterone produced by the fetus could suppress the mother's immune system and perhaps make her more susceptible to disease. There could be genetic or social differences among the Sami, who are distinct from their Finnish and Swedish neighbors, Helle said. But he does not think so. "There is no reason to believe that this effect would be only visible in Sami people," he said. "Generally, boys get on their mothers'nerves more than girls because they are running around, and girls are more willing to help their mothers." * Sami:拉普人(Lapp)的别称，指居住在北欧拉普兰地区(Lapland)的人。 Remarks:“遂令天下父母心，不重生男重生女。”