Humans throughout history and across cultures have disposed of dead bodies without just abandoning them. Frequently, these disposals have involved specific ritualized actions. In the majority. of cases the disposal of corpses involves religious ritualized actions. In this thesis, I argue that the strong tendency and perhaps even compulsion to dispose of dead bodies in ritualized ways generally, and religious ritualized ways specifically, occurs as a consequence of the evolved cognitive architecture ofhuman minds. By examining the archival records on the paleontological, archaeological, ethnographic and historical evidence of early disposal behavior by humans, as well as looking closely at early Indian Buddhist practices, and paying attention to modem Buddhist mortuary rites, I attempt to make the case, from the perspective of cognitive and evolutionary psychology, that several mental systems seem to be activated by dead bodies and that the aCtivation of the cognitive systems leads to humans perfonning religiously ritualized behaviors cross-culturally. These same mental systems, moreover, constrain the variation of mortuary rituals seen in various cultures. In pursuit of a scientific explanation ofwhy it is that humans dispose of dead bodies in the various ways that they do, I have gone beyond examining textual evide.nce by devising instruments to measure individual responses to dead bodies, and to theorize that specific cognitive systems are activated by such stimuli. I examine closely the data generated by the experimental studies and suggest a way of modeling the systems involved.