A new PLoS paper by Okanoya et al claims to show rats engaging in significant tool use. As you might expect, the paper is pretty extensive and convincing, clearly demonstrating that rats can not only use tools, but differentiate between different categories of tools in different contexts. This is another piece of evidence against the idea that only humans can use tools and that tool use is the product of some sort of higher cognitive function. Already tool use has been observed in a wide range of species, from chimpanzees to birds.
I had the pleasure of sitting next to Okanoya at dinner during Evolang. He was a lovely guy and he whipped out his laptop and showed us some of the videos in this paper. He said the paper had only really been done to prove that even rats could use tools. His team certainly wasn’t making a comment about rats in particular. As he says in the paper, this is just more evidence that “tool use is not a specific faculty resulting from higher intelligence, but is a specific combination of more general cognitive faculties”. It is important to bear in mind though that these rats were trained to use tools and we don’t have any evidence yet of natural tool use.