The Grandmother Hypothesis

A grandmother and granddaughter cooking in a kitchen together.

The grandmother hypothesis is a scientific theory which has been investigated (and continues to be worked on) for several decades.  Researchers interested in evolution and reproductive capacity are trying to uncover the reason why menopause and the stopping of reproductive activity happens at the age it does, when the human lifespan is far longer than that.

The idea that has been tested using data from communities without access to healthcare, from historical data and from computer modelling, is that menopause plays an important role in society and in reproduction in a larger sense.  The key points are:

  • Later life pregnancies are very risky, so reproductive function ceases in order to protect life
  • If a woman does have a successful pregnancy at 50, she will live long enough to raise her child
  • Grandmothers are able to provide care for their grandchildren and adult children for many years after menopause, ensuring the survival of their descendants

Humans are one of the few mammal species that continue to provide food for their offspring after weaning – we don't stop feeding our kids when we stop breast or bottle feeding.  The provision of nourishment for grandchildren is also part of the grandmother role, as seen in a paper from 2010 which studied a remote foraging and farming community[1].  Researchers found that grandmothers were very productive in terms of feeding the younger generations with each elder directly contributing 500 calories per day for their grandchildren.

The presence of grandmothers and the effect on the reproductive capacity of their daughters was shown in an analysis of the data from a settler community in Canada between 1608 and 1799[2].  The data showed that women with a living mother had twice as many children as those without, and that this effect was most apparent when the mother lived close by.  This suggests that it is the direct support and involvement of the grandmother (unburdened by small children of her own) which impacts the size of the next generation.

A similar analysis of historical data from Finland looked at the infant mortality rate of children who had a living grandmother and those who did not.  Children with a living grandmother were 30% more likely to survive past age 5 than those who did not.  Analysis of births and deaths in a region of Gambia[3] revealed that children whose mothers died before they reached the age of 2 were 10 times less likely to survive than those with living mothers.  Crucially, those children without mothers were twice as likely to survive if they had living grandmothers – the existence of other living relatives had no discernible effect.

The same research team also used computer modelling to examine what happens when the age of menopause is changed – finding fewer benefits to grandchild mortality when menopause happens later, suggesting that 50 is the evolutionary sweet spot for menopause.  If menopause happens earlier, the population grows more slowly because of the reduced window for reproduction.

So, we can see that menopause serves an evolutionary purpose for the reproduction of the family line, even when the reproductive capacity of the individual has gone.  Grandmothers are around to help feed, teach and care for their grandchildren, and the effect should not be underestimated.  Keeping busy with grandchildren is all part of the circle of life, but thanks to modern society we can still put our own health and wellbeing first and enjoy this new phase of life with a much better balance than the grandmothers in these studies.  A balanced diet, regular exercise and supplements like our MenoShake, specifically formulated to support women through menopause, will help keep you fit and well whether you're helping to raise grandchildren or not.




Leave a comment

Please note, comments must be approved before they are published