It all started with that first look.

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Smelling Good and Looking Back

You're a single lady at a crowded party, and you've just locked eyes with a man who meets with all of your mental criteria. He's made his way over, and the three-minute clock that Helen Fisher wrote about has started. If he had body odor, that would be a deal breaker, but is it possible that you can sniff out whether he's a good match in other ways?

On the last page, we talked about being attracted to people who are the same to us, looks-wise. But remember, we learned how we're also all subconsciously evaluating the genetic card this person has to play for our potential offspring. The risk of falling in love with someone too much like you is that you might be related, and inbred offspring don't have a very good chance of survival. Some researchers think that while we're sizing up how nice another person looks, we're also somehow sniffing out their genes. One famous study found that women who sniffed sweaty shirts and ranked them in terms of attractiveness tended to rank shirts that belonged to the most genetically different men the highest [source: The Economist]. And in one study of fruit flies, researchers found that one meeting was all it took for the female fruit flies to figure out which males were their best genetic match [source: Moskowitz]. While humans aren't fruit flies, the researchers posit that we possess some similar search mechanism.

Perhaps you're seeing how difficult it can be to fall in love at first sight -- the person in question has to posses the right genes and look like someone we could be with, according to our mental love maps. But just as important as finding a person who looks LIKE us, though, is finding a person who looks AT us. In a study published in the Proceedings of the Royal Society, one researcher likened love at first sight to narcissism, because it turns out what we're most attracted to is someone who happens to be looking at us. Again, this has evolutionary roots, as we shouldn't spend time chasing a mate who's not interested, but it's narcissistic because the person we tend to look at, of course, looks like us. It's like falling in love with your own image in the mirror.

And just to make it more complicated, it might all come down to what time of the month you spy a lovely lady or a handsome gent. There's evidence that women become more attuned to certain traits in men during the most fertile times in their menstrual cycles; specifically, women tend to respond more strongly to potential suitors when they're ovulating, and men, in turn, tend to find women more attractive during the same period, even when the men don't know the lady's cycle. One interesting study even found that exotic dancers tended to receive much higher tips at their most fertile points of the month [source: Canning].

Want to learn more about love? We've got plenty of links on the next page to get you started.