Ladies, how much influence do your (male) mates have over you? If people are anything like insects, it might be more than you realize.
Thankfully, humans aren’t quite insects. In the fruit fly (Drosophila melanogaster), males have a considerable amount of control over their mates. And they keep exerting their control long after they’ve moved on from a female, through proteins in their semen.
Seminal proteins tell the female to make more eggs, lay more eggs, eat more, store sperm, and use that sperm to fertilize their eggs. These things are necessary for reproduction to occur and don’t quite constitute a battle.
But the male can affect the female in more insidious ways. Some of those proteins kill her libido: she won’t mate with another male for a long time. Other proteins kill her, literally: she will have a lower lifespan because of mating. And all because of those pesky proteins.
Fortunately, females can fight back. This “arms race” between the sexes is known as sexual conflict. But to fight back, females first need to alter their own proteins, the ones that the male proteins are communicating to her through. A recent study from Cornell University has shown that female fruit flies have genetic variation for the rate of re-mating, among other traits. They’re building up their arsenal. Males also have genetic variation for the rate of female re-mating. The battle rages on! You can read more about this research here.
So, what about us? Unfortunately, we barely know what the proteins in fruit fly semen are doing in (to?) the female. We know next to nothing about the proteins in human semen. And who understands human relationships anyway?
Want to know more about conflict (and cooperation) between the sexes in Drosophila? Check out this article by Mariana Wolfner, a professor in Molecular Biology and Genetics at Cornell.