I've been suspicious of the reports of a family walking on their wrists having "evolved backward" ever since I first heard it, and I'm glad that Carl Zimmer is having some of the same concerns I have:
I can't tell from what I've read whether any of these scientists is really claiming that these people have a genetic mutation reverting them to our quadrupedal past. If they are, they're nuts. Locomotion is a fantastically complex feature, and any particular kind of locomotion is made possible by the size and shape of bones, muscles, and tendons, along with neural pathways to control them. It's not controlled by some single gene that can switch back to an ancestral state in a single family. The evolution of bipedalism took millions of years. The earliest hominids show some hints of bipedalism six million years ago, but hominids didn't walk efficiently upright like we do for another four million years. In that time, a lot of changes, both subtle and dramatic, occurred.
On the other hand, it is certainly true that unusual families can help scientists learn a lot about our origins. As I explain in my new book on human evolution, a family in London carries a mutation to a gene called FOXP2 that looks to have played a major role in the evolution of language. But it was not enough for scientists to identify a mutation in this gene in a family who had trouble talking. They needed to show that it has precise effects on language-processing regions of the brain and that it shows signs of having undergone intense natural selection. Somehow, I don't get the sense that the scientists involved with this new family are going to take that kind of care. Instead, it looks like it's turning into a televised freak show.
John Hawks, where are you?
Update March 11th: Carl Zimmer has deleted the entire discussion of wrist-walkers from his post, as it also contained what some took to be accusations of "ethical and financial hanky-panky". However, the part quoted above isn't affected by that, so I'll leave it up unless Zimmer specifically asks me to remove it.