Researchers from China have discovered that male mice who are either bred without serotonin or whose bodies just aren’t receptive to serotonin have zero interest in mating with female mice.
Known as the ‘happiness hormone,’ serotonin seems to function as a “mating call” for male mice. Those whose brains cannot process it, or those who don’t have the tryptophan hydroxylase 2 gene (which produces serotonin), therefore don’t get the desire to mate, or at least not with females.
What’s interesting is that when such mice are placed among both male and female mice, they are indifferent to both types. However, when a serotonin deprived male is left alone with another male, he’ll proceed to “mount the male and emit a mating call.
This sudden preference for other males can be reverted, however, by injecting serotonin into the mouse’s brain.
Note that this study is very inconclusive, in that it cannot be used to explain human sexuality.
“Any potential links between serotonin and human sexual preferences must be considered somewhat tenuous,” Professor Keith Kendrick said.
The results do show, however, that neurotransmitters play some sort of role in regard to sexual preference—or at least with animals.