Biological science is deepening our understanding of life at a brisk rate, but interdisciplinary discourse is not keeping pace. This essay offers an account of themes from evolutionary biology that can enrich appreciation of the complexities of human behavior. Because this topic touches fields with different and more traditional perspectives, frictions and misunderstandings exist, and I have employed examples from a single source in order to clarify the science. In her critique of evolutionary psychology published in her book Scandalous Knowledge, the social theorist Barbara Herrnstein Smith has set forth views that are not in harmony with either evolutionary biology or cognitive neuroscience. She asserts that specialized features of mental processing postulated by evolutionary psychologists are without empirical justification; further, she dismisses the concept as embracing “non-physical mental organs.” There exist, however, numerous examples of how brains process information in specific, functional ways, frequently characteristic of the species. Furthermore, the charge of “non-physical mental organs” is not only wrong; it reveals a failure to recognize that biology has two complementary modes of explanation. One is historical and addresses cause in terms of the historical course of evolution and the process of natural selection. The other is proximate and includes many levels of analysis from molecular to social. Because brains have evolutionary histories, the ‘function’ of a particular aspect of mental processing can have a hypothetical explanation in terms of adaptive advantage that is independent of any knowledge of the underlying neural circuitry. A computational model of the brain and representational processing of sensory information, however, are both compatible with observed properties of neurons in the retina and visual cortex as well as with evolutionary processes. Finally, study of the mental processes of non-human primates provides insight into the evolution of our own minds.