The human race has the capacity to render itself extinct unless alternatives are found to the patterns of intraspecific warfare that have dominated civilized history. Ours has long been a predatory species. Living, for humans, depends upon the ability to kill as clearly as it does for lions or wolves. But lions and wolves, like almost all predatory species, normally limit their killing to prey animals, and they are equipped with elaborate ritual precautions to prevent the destruction of their own kind. Humans appear to be unique among predators in their enthusiasm to destroy members of their own species. Perhaps this unusual behavior can be attributed to some genetic deficiency which may lead humans ultimately to join the rest of nature's failures in the biological graveyard of extinction. Or perhaps our willingness to kill ourselves, like so many of our other problems, is something we have devised by misusing our enlarged brains.