Big fleas have little fleas,
Upon their backs to bite 'em,
And little fleas have lesser fleas,
and so, ad infinitum.
And the great fleas, themselves, in turn
Have greater fleas to go on;
While these again have greater still,
And greater still, and so on.
Humans are simply parasites higher up the food chain. Unlike most parasites though, they haven't learned how not to destroy their hosts. So one might say they're the dumbest parasites that ever drew breath.