'Polygamy is secret to longevity'

LONDON: Forget long walks and calorie-controlled diets, the sure shot way to live a longer life is: get a second wife.

That's the conclusion of a new research, which has suggested that men from polygamous cultures outlive those from monogamous ones.

After accounting for socioeconomic differences, men aged over 60 from 140 countries that practice polygamy to varying degrees lived on average 12% longer than men from 49 mostly monogamous nations, says Virpi Lummaa, an ecologist at the University of Sheffield, UK.

The latest research might solve a long-standing puzzle in human biology: Why do men live so long? This question only makes sense after asking the same for women, who - unlike nearly all other animals - live long past the menopause.

One answer seems to be a phenomenon called the grandmother effect. For every 10 years a woman survives past the menopause, she gains two additional grandchildren, Lummaa says.

It seems that doting on and spoiling grandchildren aids their survival, as well as furthering some of their grandmother's genes. Men, by contrast, can reproduce well into their 60s and even 70s and 80s, and most researchers assumed this explained their longevity.

But Lummaa and colleague Andy Russell wondered whether other factors explained the long lifespan of men, such as a grandfather effect. To test this possibility, the team analysed church-gathered records for 25,000 Finns from the 18th and 19th centuries.

But the grandfather effect was soon ruled out. Lummaa and Russell next wondered whether the constraints of human physiology explain male longevity. If female survival is the main explanation for male longevity, then monogamous and polygamous men would live for about the same length of time. Instead, it seems that fathering more kids with more wives leads to increased male longevity. Men, then, live long because they're fertile well into their grey years.