Pandas are cuddly, but not to each other. They muster about as much enthusiasm for sex as a human does for a root canal.

In part because of those lousy libidos, the world’s giant panda population is disturbingly small. A sign at the Chengdu Research Base of Giant Panda Breeding in Sichuan Province says that “saving the giant panda from extinction is of the utmost urgency” — but the urgency isn’t felt by the pandas.

Why are they so un-frisky? Chinese scientists have been studying that question for decades, with an eye toward fomenting fornication. (China owns all of the world’s pandas, including the few that have been born abroad to parents lent out for hefty fees to foreign zoos.)

Panda biology is part of the problem. Females enter estrus only once a year, for a very short time in the spring. They are receptive and fertile for just 24 to 72 hours. A male panda needs to make his move then, or wait for another whole year. “There is perhaps no mammal that is less often in the mood for sex than the female giant panda,” Scientific American said in a 2012 article.