Asked by: Andrea R, Dublin
All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing whether sexual pleasure ever actually tips over into orgasm is hard.
Female chimps, macaque monkeys and cows have all been stimulated in the lab to the point of experiencing vaginal and uterine contractions, which does suggest that other female animals are at least capable of orgasm. Whether they regularly have them during normal copulation is much less certain; most animal sex is very brief and often quite violent.
Beyond mammals, the case for a female orgasm is more tenuous. Reptiles have penetrative sex and presumably would benefit from orgasms just as much as mammals, but I don’t think anyone has ever tried to detect the female orgasm in a crocodile or a snake. Most other vertebrates use external fertilisation; the female deposits her eggs and the male squirts them with sperm. It’s hard to see how this would trigger an orgasm in even the most excitable female. Those invertebrates that practise internal fertilisation don’t have enough of a nervous system for pleasure and orgasm to be meaningful labels.