With all the talk that the Y chromosome is fading at an incredible rate, one would think a selective process is weeding out males and their unique chromosome. X and Y ChromosomesBut a new study examines the two-sex model to show that selection favors survival for as long as men reproduce,

“Male fertility can only result from matings with fertile females, and we present a range of data showing that males much older than 50 yrs have substantial realized fertility through matings with younger females, a pattern that was likely typical among early humans. Thus old-age male fertility provides a selective force against autosomal deleterious mutations at ages far past female menopause with no sharp upper age limit, eliminating the wall of death.

Our findings illustrate the evolutionary importance of males and mating preferences, and show that one-sex demographic models are insufficient to describe the forces that shape human senescence.”

Read more the rest of the article, “Why Men Matter: Mating Patterns Drive Evolution of Human Lifespan,” over at PLOS One.