Having proved men and brutes bodies on one type: almost superfluous to consider minds. Almost but not quite:
He who understands baboon would do more towards metaphysics than Locke. What, then, to make of the 'new, scientific' study of morality by the likes of Marc Hauser, which may point to something like this:
the science [sic] of morality may bring into doubt some of our most deeply ingrained cultural perceptions about right and wrong. We’ll have new, richer opportunities to examine our actions in the presence of consequences. We probably won’t like what we see. [But] those awkward realizations may be the greatest value of moral science. How far are we here from:
No man can ever attain to anywhere near a true conception of the subconscious of man who does not know primates under natural conditions. Carlo Fausto  quotes Friedrich Nietzsche:
Our body is, after all, only a society constructed out of many souls.and Mia Couto:
In Lua-do-Chão, there is no word to say “poor.” One says “orphan.” This is true misery: to have no kin.
1. Charles Darwin, Notebooks on transmutations of species.
2. Darwin, 1838 notebook.
3. Reinventing Morality, a review of Moral Minds (2006).
4. Eugène Marais, in a letter from 1935, republished in an introduction to the The Soul of the Ape by Robert Ardrey. Ardrey was an advocate of the now unfashionable 'killer ape' hypothesis. More popular these days may be the 'kind ape' hypothesis. ('Twilight souls' is a term used by Marais to describe the Chacma baboons of the Waterberg. There is evidence that Australopithecus africanus and, later, Homo erectus lived in the Waterberg.)
5. Feasting on People: Eating Animals and Humans in Amazonia, 2007. DOI: 10.1086/518298