Penis
Domestic cats have barbed penises, with about 120–150 one millimeter long backwards-pointing spines. Upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for ovulation. Lions also have barbed penises. Male felids urinate backwards by curving the tip of the glans penis backward. When male cheetahs urine-mark their territories, they stand one meter away from a tree or rock surface with the tail raised, pointing the penis either horizontally backward or 60° upward.
Scientific racism
In Morton's "Crania Americana", his claims were based on Craniometry data, that the Caucasians had the biggest brains, averaging 87 cubic inches, Native Americans were in the middle with an average of 82 cubic inches and Negroes had the smallest brains with an average of 78 cubic inches.