Emily Hale has an ongoing series on her blog, "What makes man different from animals," (not linkable, alas, but you can search her blog for it) quoting philosophers on this question. Sometimes I am sorry when the answer amounts to either "nothing worth noting," or "their ability to agree with my political convictions." The other day though, I heard "The Animal Song," a treacly Savage Garden song from the '90s, on the radio (primarily memorable because it sounds like they're singing, "I want to live like cannibals!", which is only slightly more preposterous than the correct lyrics), and recalled that it contains the following profound contribution to Emily's catalog:
"Animals and children tell the truth, they never lie Which one is more human There's a thought, now you decide"
There's a thought indeed. This is why we appreciate that thought proceeds in other spheres, even if its results are sometimes not much better than pop music lyrics.