Sean Carroll at Preposterous Universe:
The study of cognition and sentience would be greatly abetted by the discovery of intelligent alien beings, who presumably developed independently of life here on Earth. But we do have more than one data point to consider: certain vertebrates (including humans) are quite intelligent, but so are certain cephalopods (including octopuses), even though the last common ancestor of the two groups was a simple organism hundreds of millions of years ago that didn’t have much of a nervous system at all. Peter Godfrey-Smith has put a great amount of effort into trying to figure out what we can learn about the nature of thinking by studying how it is done in these animals with very different brains and nervous systems.
More here.