3 forming a mathematical complement. sine and cosine are complementary functions. 4 (Maths, logic) (of a pair of sets, functions, etc.) mutually exclusive and exhaustive, each being the complement of the other. 5 (of genes) producing an effect in association with other genes. 6 involving or using the treatments and techniques of complementary medicine.
We know that fertility does decline. We know that after the age of 30, there is a drop in testosterone of 1 percent a year. Testosterone is the energy, the hormone that you need to make good-quality sperm.
Men make estrogen from testosterone, and women do, too, Finkelstein said. So when men age and testosterone levels naturally decline, men also experience a drop in levels of estrogen circulating in their blood. The new results suggest that when estrogen levels drop, men experience some of the same consequences that women do after menopause: They have more bone loss, their libido declines, and they gain more fat around their midsection. [Macho Man: 10 Wild Facts About the Male Body]