The pre-Darwinian history of the comparative method, 1555-1855.

The comparative method, closely identified with Darwinian evolutionary biology, also has a long pre-Darwinian history. The method derives its scientific power from its ability to interpret comparative observations with reference to a theory of relatedness among the entities being compared (the comparates). Such scientifically powerful strong comparison is distinguished from weak comparison, which lacks such theoretical grounding.

Synthesis and separation in the history of "nature" and "nurture".

For much of the 20th century scientific psychology treated the relative contributions of nature and nurture to the development of phenotypes as the result of two quite separate sources of influence. One, nature, was linked to biological perspectives, often manifest as "instinct", while the other, nurture, was taken to reflect psychological influences. We argue that this separation was contingent on historical circumstance.

Three pioneers of comparative psychology in America, 1843-1890: Lewis H. Morgan, John Bascom, and Joseph LeConte.

Scientific comparative psychology in America dates from the mid-1890s, but there is a body of earlier literature on the topic, written during a period of theistic debates over Darwinian evolution. The anthropologist Lewis H. Morgan rejected instinct as an explanation of animal behavior in 1843 and defended the mental similarities between animals and humans, although he was not an evolutionist.

An early manuscript in the history of American comparative psychology: Lewis Henry Morgan's "Animal Psychology" (1857).

Lewis Henry Morgan (1818-1881) is best known as the 1st ethnographer of Native American culture, but he also wrote on animal psychology, beginning in 1843, some 50 years before the founding of comparative psychology as a scientific discipline. Although not an evolutionist, Morgan argued that animals possess many human mental abilities, such as reason and moral judgment, and he rejected the scientific utility of the concept of instinct, a view that did not gain much currency in psychology until the rise of behaviorism in the 1920s. This 1857 manuscript, which is in the Lewis Henry Morgan Papers at the University of Rochester in Rochester, New York, formed the basis for the last chapter of his 1868 monograph on the American beaver but gives additional information on his sources and an expanded criticism of the concept of instinct.

Genes, interactions, and the development of behavior.

Explaining how genes influence behavior is important to many branches of psychology, including development, behavior genetics, and evolutionary psychology. Presented here is a developmental model linking the immediate consequence of gene activity (transcription of messenger RNA molecules from DNA sequences) to behavior through multiple molecular, cellular, and physiological levels. The model provides a level of detail appropriate to theories of behavioral development that recognizes the molecular level of gene action, dispensing with the metaphorical use of such terms as blueprints, plans, or constraints that has obscured much previous discussion.