For men hunting for a partner, testosterone’s a good thing. It boosts competitive behavior, and increases men's attractiveness to women. But the hormone has its ___1___. Men with more of it have more marital problems and divorces. One study even suggested that guys with high testosterone have less sympathy for crying infants.

But there’s good news. Because having a kid appears to cut testosterone levels—essentially ___2___ men to be better dads. So says a study in the Proceedings of the National Academy of Sciences. [Lee Gettler et al., "Longitudinal evidence that fatherhood decreases testosterone in human males," PNAS 2011]

The researchers sampled testosterone levels of over 600 21-year-olds in 2005, and again in 2009. And they quizzed them on their relationships in the interim.

Single guys with high testosterone had better luck finding mates by the study’s end, and were more likely to have become fathers. But their testosterone ___3___, compared to peers who stayed single. And the more hours a day they spent with their kids, the lower their testosterone levels fell.

Which suggests that being a nurturing dad may have ancient evolutionary roots—and that men are biologically ___4___ to shift from alpha-male to tender caregiver when bringing up baby.
【视听版科学小组荣誉出品】
drawbacks priming plunged wired
睾丸激素在男性追求女性时起到重要作用，它不仅使男性在恋爱竞争中提高恋爱技巧，而且更能提升男性对女性的诱惑力。当然，男性在婚姻上的诸多问题和离婚率都和激素分泌过多息息相关。一项研究表明，激素分泌量多的男性缺少对婴儿的关爱。 现在我们有了好的新发现——小孩子会使男性的睾丸激素分泌降低，而且性格好的男性更容易成为温柔的父亲。国家科学学术中心正在进行的一项长期研究也表明，以为人父的男性比单身男性的睾丸激素分泌量减少。 在2005年，研究人员对600名21岁的年轻进行睾丸激素分泌量记录，2009年又记录一次，期间对600名也进行过取样测试。 调查结果显示，激素分泌量多的单身男性在追求配偶时更有优势，也更容易成为父亲，当然相比任然单身的男性，他们的激素分泌量最后会降低。 这项研究让大家明白，在养育孩子的过程中，男性会从简单的男人变为懂得给予、温柔的父亲；也许，男性天生就具备这种过程的改变能力。