Some people like to think there's something fated about who we fall in love with. It's that perfect mix of attraction, compatibility, and of course timing. But in some cases, fate may be taking its cues from birth control pills.

    First, let's go over a woman's cycle and how that affects attraction. When women are ovulating, their features change in ways that men unconsciously pick up. So men are particularly attracted to women when they're fertile. And it works the other way, too. When a woman is fertile, she's more attracted to men with more traditionally masculine features and who are genetically dissimilar to her, or more compatible in terms of procreating.

    Of course oral contraception changes a woman's hormonal cycles. Her body thinks it's pregnant and doesn't go through ovulation-induced changes. And in a study published this month in the journal Trends in Ecology and Evolution, researchers say that women on the pill do not show the ovulation-induced attraction to genetically dissimilar partners. So they might be choosing men who are more genetically similar-which could lead to some of the problems with conception that have become increasingly common. Because attraction isn't fate. It's chemistry.

    很多人傾向于認為愛由天注定，需要一系列的相互吸引和共同語言，當然還有恰當的時機。但，在某些情況下，避孕藥就能搞亂所謂的命中注定。

    首先，讓我們來看看女性的生理周期是如何影響她們的魅力的。當女性處于排卵期，男性在不知不覺中就能捕捉到她們體征上的一些變化，并為之吸引。反過來，當一位女性處于排卵期時，她也更容易被那些具有陽剛特征的男性所吸引，這主要是基于生育后代的考量，那些與自身基因具有較大差異的異性更受歡迎。

    眾所周知，口服避孕藥能改變女性的內分泌。當服用過避孕藥，藥物中的孕激素使得女性卵巢停止排卵，也就不能發生上訴的效應。在本月出版的《生態學與進化動向》期刊上的一份研究報告里，研究者們聲稱，服用避孕藥的女性并未對與自身基因具有較大差異的男性顯示出特別的吸引力。類似的，這些服用避孕藥的女性在擇偶時也就不那么具有優勢生殖的判斷力了。由此導致的結果也越來越為人所知，也就是人種的退化。看來，愛情這東西，才不是什么緣分天定，而是一道化學分子式。