Man looking at a woman

In some cases, men may be shortening their own lives by competing for a significant other.

A new study suggests that when men reach their maturity sexually, when far exceeding the female population, men experience an average lifespan three months shorter than males from areas when the gender ration (man to woman) is more equal.

Other studies have observed this theory in animals, but this is the first time humans are being evaluated based on this concept.

While three months may seem insignificant at first, researchers compare it to taking an aspirin each day or moderately exercising. They explain a man who is 65 years old is generally expected to live about 15 more years. Taking away three months from that time is much more noticeable than first thought.

For the purposes of this study, researchers analyzed individuals who graduated from high schools in Wisconsin in 1957. Calculated were the gender ratios of each graduating class as well as the life span of each graduate.

As of 2007, men from classes with more males than females had a shorter overall lifespan than those from classes experiencing a less male-favorable gender balance. The difference in the life spans for men, age 65, was 1.6 percent.

Researchers failed to analyze additional reasons for these findings, but explained many factors could affect this outcome. Stress of finding a significant other may be stressful, and a known cause of many health problems is stress.