BBC News – Sexual preference chemical found in mice
As the story points out, going from this to human brains requires a whole bunch of speculative leaps (including the obvious one) that a serotonin-free brain is functioning normally at all. Without checking the rats on a wide range of other cognitive tasks, you’re pretty much picking the one bit of weird behavior in their brains that might make headlines.
(On the other hand, there’s lots of evidence of SSRIs leading to sexual dysfunction and messing with libido, so at least this result is in the same solar system.)
