March 21 (UPI) -- Scientists believe wild animals, including cats, wolves and pigs, became more promiscuous as their population densities increased near human settlements. And according to researchers at the University of Liverpool, this shift in reproductive behavior paved the way for domestication.
"As population density increased, males encountered mating opportunities more frequently, and the benefits of pursuing these likely outweighed the costs of attempting to defend exclusive access to females," biologist Paula Stockley said in a news release. "Polyandrous mating therefore often increased with high population density."