Two of a Kind.

During a late night at the Yale lab, Monk mentioned this to a heterosexual colleague, biologist Max Lambert. Paul Vasey, a sex researcher at Canada's University of Lethbridge, has spent three decades studying female Japanese macaques, or snow monkeys, who often enjoy short-term sexual "consortships" with one another. Max was distraught. "I remain unconvinced", says Vasey, who believes that Monk and Lambert's argument "assumes an evolutionary similarity among same-sex sexual behavior across the animal kingdom.". [Extracted from the article]