Embryonic Recapitulation

By considering the embryological structure of man - the homologies which he presents with the lower animals - the rudiments which he retains - and the reversions to which he is liable, we can partly recall in imagination the former condition of our early progenitors; and we can approximately place them in their proper position in the zoological series. We thus learnt that man is descended from a hairy quadruped, furnished with a tail and pointed ears, probably arboreal in its habit, and an in...

 The Term "Higher Animals"

So glibly do the phrases 'higher animals' and 'lower animals' trip off our tongues that it comes as a shock to realize that, far from effortlessly slotting into evolutionary thinking as one might suppose, they were - and are - deeply antithetical to it. We think we know that chimpanzees are higher animals and earthworms are lower, we think we've always known what that means, and we think evolution makes it even clearer. But it doesn't. It is by no means clear that it means anything at all. Or...