It's too simplistic to basically say, 'Oh well, our closest primate relatives have these genital swellings
and therefore men are reacting to red coloring'," said study researcher Sarah Johns, anthropologist at the University of Kent.
At the indifferent stage, the external genitalia consist of the genital tubercle, genital fold, and genital swellings (Figure 4-12).
These changes bring the genital swellings closer together to form the scrotum.
Two genital swellings
known as labioscrota separate, in the female, to become the labia majora, and in the male unite to form the scrotum.