This essay will critically evaluate biological and behaviorist psychological perspectives. A psychological perspective is a theory that attempts to explain human behaviors and motivations. The biological approach, introduced around 1880, argues that human behavior is determined by the anatomical structure of the brain. Including the chemicals it produces and how they interact with each other. This approach is deterministic: it holds that all human behavior is determined solely by our genetics, brain mechanisms, and neurochemicals such as hormones. The Dunedin longitudinal study will be evaluated from this perspective. The humanistic perspective has its origins in existential philosophy. He argues that the world is ultimately meaningless and that people are free to choose their own worthwhile personal destiny (Maslow, 1943). The “Cindy” case study will then be evaluated from a humanistic point of view. Finally, humanistic therapy – person-centered therapy – will be evaluated. The essay will then attempt to reach some conclusions about which approach best explains human behavior. Francis Galton, Darwin's half-cousin, was a key early propagator of this approach. He argued that talent is passed down through family lineage; that is, geniuses (those geniuses are born, not made). Galton, however, recognizes the benefit of education and social influences in “developing the active powers of the mind” (Galton, 1869, p. 14). Noam Chomsky argued that humans are born with the basis for understanding language and that this genetic ability was independent of cultural or social differences (Lyons, 1978, p. 7). This idea supports prepared learning theory; the idea that certain behaviors are genetically coded to facilitate learning. Some of the most common human phobias are; snakes, spiders, deep water and