Nature vs. Nurture: the Genetics of Behavior

Although today there is a wide acceptance that both genetics and environmental experiences define an animal’s behavior, at one time it was thought that perhaps environmental experience alone determined an animal’s behavior. Some of the first definitive work, published by Tryon in the 1940's, supported the genetic basis of behavior. Tryon studied rats and their ability to complete a maze. He grouped the rats that made the fewest errors and completed the maze the most quickly (maze-bright) and he grouped the rats that made the largest number of errors and took the longest to complete the maze (maze-dull). He bred maze-bright to maze-bright and maze-dull to maze-dull. Within seven generations he obtained a statistically significant difference in completion of the maze between the maze-bright rats and maze-dull rats. These rats were raised in identical environmental conditions. Subsequent to this first work, multiple studies have been published regarding the ability of genetics to influence multiple different behaviors in multiple different species.