首页 > 英语听力

美联英语怎么样:男性生物钟

2015-02-06 13:58   类别:听力   来源:   责编:Dong

本期美联英语给大家带来男性生物钟,欢迎阅读!

There's a common belief that men can sire children until they die, but that women need to be relatively young to conceive healthy children. But the father's age affects the child's health too. Psychiatrist Dolores Malaspina and her team found that the risk of schizophrenia triples for babies born to fathers over 50, compared with fathers under 25. Other diseases appearing more in offspring of older fathers are achondroplasia, or dwarfism, and some prostate cancers.

Despite the publicity given to women's biological clocks, medical geneticists recently have found that sperm are more likely than eggs to have genetic mutations. Here's why. By age 40, a man's sperm cells have divided over 600 times. That's over 600 chances for mistakes in copying genes. A woman's eggs, on the other hand, don't go through that process of division, so there are fewer chances for mistakes in gene replication. When there is a genetic problem in an egg, though, it's often with a whole chromosome, instead of a single gene. Down syndrome, for example, occurs when there's an extra copy of chromosome 21. Most babies with older fathers, as with older mothers, are healthy. Still, biological clocks are real, and not just for women. His biological clock is ticking too!

更多精彩内容尽在绍兴美联英语:http://sx.enguo.com

赞一下( ) 收藏
适合人群:
难度:
标签:听力  
上一篇:无 下一篇:美联英语怎么样:快速减肥法
我要参与
验证码:   看不清楚,换张图片
精彩活动