Not very long ago sex was driven by reproductive needs. Because life was often cut short by illness or poor nutrition, sex had to be fast and frequent. In modern times, sex is less about reproduction and more about relationships and communication. What’s more, as people live longer, couples have the opportunity to engage in sex for many more years than their ancestors. But the ability of a man to achieve and maintain erections diminishes with age. Erectile dysfunction, once called "impotence", is the technical term for any problem achieving or maintaining an erection, and, with people living longer, erectile dysfunction is a concern for growing numbers of men and their partners.

What happens during an erection?
    An erection is basically about blood flow. When an erection occurs, blood enters the flaccid penis when a neurological signal from the brain via the spinal cord releases a chemical neuro-transmitter. Dilation of arteries follows, and blood is trapped in the erect penis, maintaining an erection. This complex process, called veno-occlusion, relies on a healthy valve effect. A faulty "valve" (called "venous leakage") allows blood to leave the penis too early.