Delbert Duane Thiessen is an American psychology professor emeritus whose research focused on evolutionary mechanisms of reproduction and social communication.
At the University of Texas he taught Comparative Psychology and investigated animal communication and human biology and behavior.
He continues his investigations of human deviant behaviors, writes fiction and non-fiction, and publishes a weekly blog: www.darksideofthebrain.com.
His hobbies include exploring history and literature, playing blues harmonica, and enjoying billiards.
In 1994 he was one of 52 signatories on "Mainstream Science on Intelligence,[2]" an editorial written by Linda Gottfredson and published in The Wall Street Journal, which declared the consensus of the signing scholars on issues related to intelligence research following the publication of the book The Bell Curve.