What is twain's claim in the lowest animal?

I have been scientifically studying the traits and dispositions of the "lower animals" (so-called), and contrasting them with the traits and dispositions of man. I find the result humiliating to me. For it obliges me to renounce my allegiance to the Darwinian theory of the Ascent of Man from the Lower Animals; since it now seems plain to me that the theory ought to be vacated in favor of a new and truer one, this new and truer one to be named the Descent of Man from the Higher Animals.