微博上闹得沸沸扬扬的“且行且珍惜”不知你关注了没有？在爱情里，哪里有什么输赢，但或许从科学上我们可以解释一下“出轨”这件事。在人类学家 Helen Fisher 的 TED 演讲中，她阐述了自己认为决定爱的三大脑组织：欲望、浪漫的爱情和依赖感。而出轨这件事，可以这样解释：

【演讲内容节选】

But these three brain systems: lust, romantic love and attachment, aren't always connected to each other.
这三个大脑组织：欲望、浪漫的爱情和依赖，并不总是彼此相关。

You can feel deep attachment to a long-term partner while you feel intense romantic love for somebody else, while you feel the sex drive for people unrelated to these other partners.
你可以对一个长期的伴侣有深深的依赖感，同时与另一个人享受浪漫的爱情，并且还能同时对一个不相关的第三人产生性欲。

In short, we're capable of loving more than one person at a time. In fact, you can lie in bed at night and swing from deep feelings of attachment for one person to deep feelings of romantic love for somebody else.
简单来说，我们可以同时与不止一个人相爱。事实上，你晚上躺在床上可以一会儿想想那个你对他有依赖感的人，一会儿想想那个跟你有浪漫爱情的另一个人。

It's as if there's a committee meeting going on in your head as you are trying to decide what to do. So I don't think, honestly, we're an animal that was built to be happy; we are an animal that was built to reproduce.
你的大脑就像在开代表大会似的，你在思考下一步要做什么。所以说实话，我觉得我们是以繁殖为目的的物种，而不是以幸福为目的。

I think the happiness we find, we make. And I think, however, we can make good relationships with each other.
幸福，是我们发现和创造的。我认为，我们可以与每个人建立美好的关系。

【主讲人介绍】

Anthropologist Helen Fisher studies gender differences and the evolution of human emotions. She's best known as an expert on romantic love, and her beautifully penned books — including Anatomy of Love and Why We Love — lay bare the mysteries of our most treasured emotion.
人类学家 Helen Fisher 致力于研究性别差异与人类情绪的进化。她是研究爱情的专家，出版的著作有《爱的解析》和《爱的原因》，书中她为我们揭示了情绪的奥秘。