Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Leonard J. Beuving

Second Advisor

Dr. Jack Wood

Third Advisor

Dr. Ronald Hutchinson

Access Setting

Masters Thesis-Open Access



It is now well established that androgens and estrogens are intricately involved in influencing the sexual differentiation of the brain, as well as male and female differences of aggressiveness. Evidence is accumulating which indicates that these steroid hormones influence the pattern of nervous connection and organization developing in utero and in the early postnatal period.

To more completely link testosterone's involvement with aggressive behavior, one must examine the voluminous literature which links testosterone with developing neonatal correlates of aggression as well as with adult capacity to display aggressive behavior. In most species the male is more aggressive than the female (Thomson, 1967; Seward, 1945; Ulrich, 1938), Unlike the female of most mammalian species, the male requires androgenization neonatally for a characteristically male type morphological, sexual and aggressive behavioral development. Castrating male mice reduces their aggressiveness and testosterone replacement will restore that aggression (Edwards, 1970; Sigg et al., 1966; Bevan et al., 1958), Castration performed during the first two days after birth effectively blocks aggression in adulthood. As the time of castration advances from birth, testosterone replacement in adulthood becomes progressively more effective in restoring aggression (Peter et al., 1972; Edwards, 1969).

Included in

Biology Commons