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.
【視聽版科學(xué)小組榮譽(yù)出品】
drawbacks priming plunged wired
睪丸激素在男性追求女性時(shí)起到重要作用，它不僅使男性在戀愛競爭中提高戀愛技巧，而且更能提升男性對(duì)女性的誘惑力。當(dāng)然，男性在婚姻上的諸多問題和離婚率都和激素分泌過多息息相關(guān)。一項(xiàng)研究表明，激素分泌量多的男性缺少對(duì)嬰兒的關(guān)愛。 現(xiàn)在我們有了好的新發(fā)現(xiàn)——小孩子會(huì)使男性的睪丸激素分泌降低，而且性格好的男性更容易成為溫柔的父親。國家科學(xué)學(xué)術(shù)中心正在進(jìn)行的一項(xiàng)長期研究也表明，以為人父的男性比單身男性的睪丸激素分泌量減少。 在2005年，研究人員對(duì)600名21歲的年輕進(jìn)行睪丸激素分泌量記錄，2009年又記錄一次，期間對(duì)600名也進(jìn)行過取樣測試。 調(diào)查結(jié)果顯示，激素分泌量多的單身男性在追求配偶時(shí)更有優(yōu)勢，也更容易成為父親，當(dāng)然相比任然單身的男性，他們的激素分泌量最后會(huì)降低。 這項(xiàng)研究讓大家明白，在養(yǎng)育孩子的過程中，男性會(huì)從簡單的男人變?yōu)槎媒o予、溫柔的父親；也許，男性天生就具備這種過程的改變能力。