Your grandmother’s help with raising you wasn’t an accident: It was a biological and social necessity that was needed to help you and your mother survive and have more children.

Unlike most female animals that keep reproducing until they die, women continue to live after menopause.

This evolutionary explanation sometimes referred to as the "grandmother hypothesis" has stated that women live beyond their ability to have children because the advantage of helping their daughters give birth and raise their children outweighs the advantage of being able to reproduce them.

Grandmothers, who are not busy feeding children, have more time on their hands to help with the grandchildren seems to suggest that natural selection favored menopause.

In a study, data was collected on 537 women, tracking the families from 1702 to 1823, and studying the life span of the women.

Results from the study showed that on the average, more children were born with families whose grandmother was still living when their children began having children. The results also showed that more children survived when the grandmother was around, lived nearby and was available to help with raising the grandchildren.

Experts also discovered that social reasons explain that once their children reached menopause and no longer could have children, the grandmothers were more likely to die.

Research has also shown how much of an impact postmenopausal women have on the reproductive success of their kids and survival of their grandchildren.

American Journal of Human Biology May-June 2003; 15(3): 380-400