and behavior, both as individuals and socially. Most fundamental are the advanced intellectual faculties, which allow humans to categorize (see individual objects as members of general classes), think in the abstract and form images of realities that are not present (and, thus, anticipate future events and planning future actions), and reason. Other distinctive functional features are self-awareness and death awareness; symbolic (creative) language; tool making and technology; complex and extremely variable forms of cooperation and social organization; legal codes and political institutions; science, literature, and art; and ethics and religion (Cela-Conde and Ayala, 2007).
Humans live in groups that are socially organized, and so do other primates. But primate societies do not approach the complexity of human social organization. A distinctive human social trait is culture, which may be understood here as the set of non-strictly biological human activities and creations. Culture in this sense includes social and political institutions, ways of doing things, religious and ethical traditions, language, common sense and scientific knowledge, art and literature, technology, and in general all of the creations of the human mind. Culture “is a pool of technological and social innovations that people accumulate to help them live their lives” (Pinker, 2002, p. 65). The advent of culture has brought with it cultural evolution, a superorganic mode of evolution superimposed on the organic mode, which has, in the last few millennia, become the dominant mode of human evolution. Cultural evolution has come about because of cultural change and inheritance, a distinctively human mode of achieving adaptation to the environment and transmitting it through the generations (Cela-Conde and Ayala, 2007; Varki et al., 2008; Cosmides et al., Chapter 15, this volume; Deacon, Chapter 14, this volume; Pinker, Chapter 13, this volume; Richerson et al., Chapter 12, this volume).
I will define moral behavior for the present purposes as the actions of a person who takes into account in a sympathetic way the impact the actions have on others. A similar definition is advanced, for example, by David Copp in The Oxford Handbook of Ethical Theory (2006, p. 4): “[W]e can take a person’s moral beliefs to be the beliefs she has about how to live her life when she takes into account in a sympathetic way the impact of her life and decisions on others.” Altruism may be defined in a similar way as, for example, “unselfish regard for or devotion to the welfare of others” (Mish, 1998). Altruism, however, is usually taken to imply some cost to the altruist for the benefit of others, and this is the sense in which I will use “altruism” here. Moreover, “altruism” is often predicated on the