So, despite voicing concerns that the Carnival of Evolution is in a slump, it was posted on time yesterday, and contains 26 posts. Which is in the lower end (hmm, I'm considering generating some stats on this now), but still more than enough for a blog carnival - if you compare to many other carnivals, e.g. on BlogCarnival, you'll see 26 isn't so bad after all.
This is the hand of Australopithecus sediba [wiki], a 2 million year old fossil. What was the use of this hand? It has been suggested that it was used to handle tools, and thus that this was the reason it came to look like this. And by inference, that our hands evolved for tool use. But is there evidence for this explanation, that there was selection for hands that could handle tools? Ken Weiss argues that there is not, and that an equally good explanation is that they evolved for masturbation.
However, as hypotheses, I still think we can differentiate. Ken admits his hypothesis may appear silly, but explains that there really isn't evidence for either one. So okay, I can also come up with a hypothesis that is even sillier (I surmise that hands evolved as adaptations for sign language*), but some hypotheses are more equal than others, I'd say. Tool used may be a "tired old idea", but it's still a viable one.
* Wait, that may not be so incredibly silly after all...