The Myth of Male Power, by Warren Farrell, Phd. Testosterone is more than a hard-on on call. Most of its benefits include greater muscle repair, anti-depression, cardiovasular benefits, and many types of repair services we don't want to lose. The erection power alone also requires growth hormone, estrogen, HCG, muscle tone, good circulation, a balanced nervous system and an available imagination. All of these can get messed up as we age.
Hormones work together in a web-like design of chemical balance between our brain and body.
They are how thought turns into body chemistry. The hormones are difficult to understand, but if you make the effort, potential benefits to your health and happiness are enormous. They are in steep decline for too many reasons. Both sexes need testosterone for libido, healthy hearts, and muscle tone. A common age-related decline in testosterone is observed to be a straight line down from the late 20's and early 30's, until whenever death takes us.