In The Descent of Man, and Selection in Relation to Sex, published in 1871, Charles Darwin wrote: "I fully ... subscribe to the judgment of those writers who maintain that of all the differences between man and the lower animals the moral sense or conscience is by far the most important." I raise the question of whether morality is biologically or culturally determined. The question of whether the moral sense is biologically determined may refer either to the capacity for ethics (i.e., the proclivity to judge human actions as either right or wrong), or to the moral norms accepted by human beings for guiding their actions. I propose that the capacity for ethics is a necessary attribute of human nature, whereas moral codes are products of cultural evolution. Humans have a moral sense because their biological makeup determines the presence of three necessary conditions for ethical behavior: (i) the ability to anticipate the consequences of one's own actions; (ii) the ability to make value judgments; and (iii) the ability to choose between alternative courses of action. Ethical behavior came about in evolution not because it is adaptive in itself but as a necessary consequence of man's eminent intellectual abilities, which are an attribute directly promoted by natural selection. That is, morality evolved as an exaptation, not as an adaptation. Moral codes, however, are outcomes of cultural evolution, which accounts for the diversity of cultural norms among populations and for their evolution through time.

The time of origin of the animal phyla is controversial. Abundant fossils from the major animal phyla are found in the Cambrian, starting 544 million years ago. Many paleontologists hold that these phyla originated in the late Neoproterozoic, during the 160 million years preceding the Cambrian fossil explosion. We have analyzed 18 protein-coding gene loci and estimated that protostomes (arthropods, annelids, and mollusks) diverged from deuterostomes (echinoderms and chordates) about 670 million years ago, and chordates from echinoderms about 600 million years ago. Both estimates are consistent with paleontological estimates. A published analysis of seven gene loci that concludes that the corresponding divergence times are 1,200 and 1,000 million years ago is shown to be flawed because it extrapolates from slow-evolving vertebrate rates to faster-evolving invertebrate rates, as well as in other ways.

Biodiversity—the genetic variety of life—is an exuberant product of the evolutionary past, a vast human-supportive resource (aesthetic, intellectual, and material) of the present, and a rich legacy to cherish and preserve for the future. Two urgent challenges, and opportunities, for 21st-century science are to gain deeper insights into the evolutionary processes that foster biotic diversity, and to translate that understanding into workable solutions for the regional and global crises that biodiversity currently faces. A grasp of evolutionary principles and processes is important in other societal arenas as well, such as education, medicine, sociology, and other applied fields including agriculture, pharmacology, and biotechnology. The ramifications of evolutionary thought also extend into learned realms traditionally reserved for philosophy and religion.

Values are a universal attribute of humankind. All humans have moral values; that is, they accept standards according to which their conduct is judged right or wrong, good or evil. People have also other sorts of values: economic, aesthetic, gastronomic, and so on. Where do moral values come from? Some moral values are widespread and perhaps universal, like not to kill, not to steal, and to honor one’s parents. But the moral values by which people judge their behavior vary at present from culture to culture and have changed in important ways through historical times. Different ethnic groups, different nationalities, different tribes, and even different individuals exhibit different moral values and different norms by which they evaluate their actions. Think of the difference between a modern American and an Islamic fundamentalist with respect to the rights of women, or between most modern Americans and the official doctrine of the current Russian government concerning homosexuality.2 Darwin expressed horror at the burning of widows by Hindus and thought absurd the proscription of Muslim women to expose their faces.