Imagine giving birth to a baby and not being able to tell for weeks whether it's a boy or a girl. That's pretty much how life rolls for pandas — a species that, we've pointed out here before, are already saddled with incredibly complicated sex lives.
On Friday, there was a baby panda born at the Smithsonian National Zoo in Washington D.C., but we don't yet know what sex the cub is. That's because male panda genitalia — both the penis and testicles — doesn't descend until after birth. It could take weeks, or months, before you can tell the cub's sex, just by looking. In the meantime, zoo staff have taken a DNA sample that will reveal the secret in 2-3 weeks.
What's particularly interesting about this, though, is that the tendency to look sort of mannequin-y at birth isn't all that rare among bear species. The sloth bears and spectacled bears have the same issue. Meanwhile, it can be hard to determine the sex of even full-grown polar bears, because their penis is retractable and their genital region (on both sexes) is so furry. Presumably, the bears have an easier time with this question than humans do.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.