Can more sex make up for less life?

Does an extra dose of testosterone pay long-term dividends? A higher level of the hormone increases sex drive and attractiveness of males, leading to more offspring and increased evolutionary fitness; it also weakens the immune system, amplifies stress, and encourages recklessness, increasing the risk of departing the gene pool altogether. Looking at songbirds, Wendy Reed, a physiological ecologist at North Dakota State University, set out to determine whether, evolutionarily speaking, a little extra machismo is really worth it. And since testosterone has pretty much the same effect across all species, her results probably extend to humans as well.