McGuire & Troisi build a case for Darwinian Psychiatry as a science of human behavior, then offer evolutionary models of mental conditions including depression, personality disorders, schizophrenia, phobias, anorexia nervosa, suicide and others. The thesis that psychiatry can achieve the status of a science has its basis in a theory of behavior which has structured protocols and agreed upon methods for testing hypotheses. At the same time the attempted program is as complex and far reaching as the human subject itself, integrating genetics, physiology, ethology, behavioral sciences, psychology and sociology into an understanding of human behavior and mental conditions. Darwinian psychiatry differs from psychiatry’s prevailing models in that the Darwinian model is based on a theory of behavior that applies concepts from evolutionary biology including: ultimate causes, biological motivations-goals, sexual selection, traits and trait variation, and the social environment. At least four ultimately caused (selectively influenced) behavior patterns or systems are thought to apply to "Homo sapiens": survival, reproductive, kin assistance and reciprocation systems. A person’s mental health will be, in part, determined by how well he or she functions to achieve their often predetermined goals in each of these areas. The primary goal of therapy designed in an evolutionary context is to improve the individual’s capabilities to achieve these short-term biological goals. The following are examples of evolutionary analysis applied to specific disorders:   McGuire & Troisi address selected objections to the use and utility of evolutionary concepts to psychiatry. "Objection": Evolutionary theory is a reductionist discipline that seeks to understand behavior and mental states as a function and process of genes. Such an approach is too limited and too unsupported with scientific data to be useful. "Response": Darwinian Psychiatry is not a highly reductionist theory of behavior. In fact, Darwinian Psychiatry makes a strong case for the importance of learning, culture and social context on development and behavioral outcomes. "Objection": Some theorists argue that the last period of intense selection for many of the present day traits of "Homo sapiens" occurred during a period of time between 100,000 and 10,000 years ago, called the environment of evolutionary adaptation or EEA. "Homo sapiens" has largely ceased to evolve genetically, morphologically or physiologically following that time period. Psychological capacities for mediating behavior rather than behaviors per se were the traits favored by selection during EEA and the selection favoring psychological capacities most parsimoniously accounts for human behavioral plasticity. "Response": There is the possibility that "Homo sapiens" is still undergoing genetic change.