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. John Bascom's textbook Comparative Psychology (1878) is the earliest American work to use that title, and its theistic approach anticipates some arguments found in much later evolutionary works. Beginning in 1860, the geologist Joseph LeConte, who is well known for defending the compatibility of evolution and religion, wrote several articles in which he outlined a comparative evolutionary approach to psychological problems. However, these writers did not establish a coherent research tradition and were ignored by the "New Psychologists" of the 1880s.