Human Libido = Mouse Libido?

(crossposted from The Naive Observer)

No! Right? Maybe some sociobiologists would argue that they obey the same basic rules, but no, not the same. Not so fast though – anyone who has had to defend their mouse research against doubts about its relevance will tell you (a little too earnestly) that there is around 90% similarity between the mouse and human genomes. So in all your faces, non-mouse geneticists.

Many of us use mice and rats as model organisms to study things from a genetic point of view with reasonable hope that info gleaned from rodents will inform our knowledge of human biology and direct “less invasive” research on humans. But there’s no denying that humans and rodents are very different. So where do we draw the line when inferring from rodent studies? This problem is especially relevant in neuroscience, where we are caught trying to bridge the gap between the physical, cellular, genetically influenced brain and the less tangible, socially conditioned mind. What better way to give air to this issue than by juxtaposing the genetics and neural correlates of mouse and human libido?

Last year I reviewed a study that discovered that male mice release a small aphrodesiac molecule (ie pheromone) in their tears. This small molecule, called ESP1, makes female mice more receptive to males’ sexual advances. In other words, female mice are turned on by the smell of tears in their man’s eyes.

So, er… “a friend of a friend” read that study, was thoroughly convinced and, armed with the knowledge that mice and humans are genetically quite similar, took his tears to the bedroom, hoping to turn over a new leaf. Unfortunately he neglected to look at what seemed to be a follow up study in humans in the new year. Turns out female human tears contain a substance that does the exact opposite, decreasing male arousal when the men sniffed paper soaked in tears collected from women. (Is sniffing tears not creepy? What ethics committee approved that?) True enough, the authors only looked at female tears, so maybe there is a human analogue of the male mouse tear aphrodisiac. So, in the interest of being fully honest, guys, if you want to run the risk, you can still have a go at crying. However, it turns out that the friend of a friend shouldn’t have risked it; last I heard he’s lonely and writing a blog or something.

The point is that humans and mice are similar in some instances, and opposites in others. So there is no point. Rest assured that rodents will continue to provide a popular and invaluable model organism well into the future. That means when you see something in the paper to the tune of “Now-Famous Scientists Show Such and Such Will Make Someone Special Horny” or not, before hitting the streets in search of Such and Such, figure out what species the research was done on and make your own tentative judgment.

Reference

Gelstein S, Yeshurun Y, Rozenkrantz L, Shushan S, Frumin I, et al. 2011. Human Tears Contain a Chemosignal. Science 331: 226-30