How has evolution shaped human behavior? Richard Alexander's contribution to an important question

Richard Alexander has been a major contributor to the development of theory concerning the evolution of human sociality. His most important contributions include (1) a theory of the evolution of morality as a form of indirect reciprocity that aids in intergroup competition, (2) a theory of the relationship between biological evolution and culture, (3) an elaboration of Humphrey's theory of the human intellect as a social tool, (4) theories about human parental investment and nepotism, and (5) theories about scenario building, consciousness, and human communication. He also has offered a hypotheses on a large range of other human traits. He is a biologist and has also made major contributions to theories of speciation, communication, eusociality, and social organization in nonhuman animals and has contributed extensively to the study of a number of specific taxa other than the human species: crickets, katydids, cicadas, naked mole rats, and horses. His contribution to the study of nonhuman animals and evolutionary theory, in general, are sufficient to earn him a reputation as an outstanding leader in biology without reference to his work on humans. The same can be said for his contribution to the understanding of human sociality taken alone.