Closing lecture presented by Dr. James E. Deacon on May 17, 1974 for the University of Nevada, Las Vegas (UNLV) Environmental Studies course "Man and the Environment." Deacon presents his students with a question of what makes "man" unique among all the creatures of the Earth and suggests that it begins with the ratio of brain to brawn. He reminds them that the course was considered as much a social science as a natural science because of the questions it had posed them, and mentions the involvement of UNLV history professor Dr. Scott Locicero. The remainder of the lecture delves more deeply into how humans learned to exploit their environment and control against hunger, predation, and disease, but without consideration for the limits of that exploitation. He closes by suggesting that the modern world may prove to be a "DIY extinction event" if humankind fails to modify its actions.