Biologists have puzzled, therefore, over what factors might have caused the human penis to become so large. They diversify earlier than other physical traits, with a wide variation in size and shape across the animal kingdom that can reveal a species’ evolutionary pressures. The finding suggests that women’s preferences could have fuelled the evolution of the human male penis, which is longer and thicker than that of any other primate. Researchers report today that penis size does matter to women - though within limits.
