Love at First Sight Might Be Genetic

By Clara Moskowitz
Love at first sight could be real, at least when it comes to genetics, a new study suggests.

In research done with fruit flies (but which may have implications for humans) scientists found that females are biologically primed to sense which males are more genetically compatible with them, and to make more eggs after mating with good matches than they do with less compatible matches. The findings suggest that females can somehow judge a potential mate upon first meeting and biologically react to boost the chances of producing successful offspring.

The researchers mated female fruit flies with males from the same strain, and from a different strain, and noted differences in reproductive attributes and behavior soon after mating. When females mated with males that were not of the same strain, they seemed to be able to tell that they were more genetically compatible, perhaps because their progeny would be less inbred, and produced more eggs and more offspring.

It appears the females can sense which males are closely related to them — a factor that can lead to genetic defects — and respond better to males that are expected to produce healthier offspring.

"You could call it love at first encounter. That might be the most accurate, because we don’t really know what about this encounter is driving this response," said study co-author Andrew Clark of Cornell University, explaining that it wasn't just sight, but perhaps smell or sound or some other sense that alerted a female her biological match was near.

The scientists discovered that the females seemed to be in a primed state even before meeting the males, with the chemicals and proteins needed for their response already in place, without the need for new genes to be activated, as the researchers expected.