Many of our legal and ethical principles depend on the separation between Homo sapiens and all other species. Of the people who regard abortion as a sin, including the minority who go to the lengths of assassinating doctors and blowing up abortion clinics, many are unthinking meat-eaters, and have no worries about chimpanzees being imprisoned in zoos and sacrificed in laboratories. Would they think again, if we could lay out a living continuum of intermediates like the California salamanders? Surely they would. Yet it is the merest accident that the intermediates all happen to be dead. It is only because of this accident that we can comfortably and easily imagine a gulf between our two species - or between any two species, for that matter.
— Richard Dawkins, The Ancestor’s Tale
Children of Agent Orange