Humans are animals. Biologists have come up with a clear set of requirements that ensure cooperative and altruistic behavior among all animals, including humans (“On Reciprocal Altruism,” February 12, 2015). Such behavior applies only in tight-knit and stable communities of several hundred animals. All evidence suggests that humans have evolved in communities of this character. The gradual dissolution of tight-knit and stable communities has started with the current interglacial period, which has ushered the agricultural revolution about ten-thousand years ago. The onset of the industrial revolution around two-hundred years ago has contributed to the further growth of human communities. Cooperative and altruistic behavior is incompatible with communities of several billion humans in existence today. The only hope for its return is the return to tight-knit and stable communities of yesteryear due to climate change followed by the onset of the next glaciation. Over several interglacial periods, the human species may evolve to the point where cooperative and altruistic behavior is conceivable even in large communities of several million animals, assuming that such behavioral patterns will ensure better adaptation of the species to its natural environment. When it comes to ethics, biologists are real pros. All the other scientists are only dabbling in the subject, not to mention philosophers or theologians.