I've received quite a few emails about the following story, presumably because it seems like something lifted from Monty Python's Ministry of Silly Walks. A family in Turkey contains five siblings who have apparently never learned how to walk on their feet. They still walk on all fours, with the weight of their upper bodies supported by their wrists (wrist walking, as opposed to knuckle walking, which is what apes do). You can check out a video of one of these wrist walkers
on the website of Turkish researcher Uner Tan.
The case of these wrist walkers is far too widely reported to be a hoax. Apparently there's even a BBC documentary about them in the works. Scientific interest in them stems from the light they might shed on a long-standing debate about how humans evolved the ability to walk upright. Were humans knuckle walkers (like other primates) or wrist walkers before they started walking on two feet?
There's also debate about whether these Turkish siblings are merely suffering from a form of brain damage and never learned how to walk upright (this theory is argued by a team of British researchers
... their paper is at the top of the list of articles), or are the siblings a case of reverse evolution (the Turkish researcher Uner Tan is arguing this). Whatever the case may be, none of it seems to be a hoax.
World Science has a couple of informative articles about the controversy (article 1
, article 2