Tag Archives: health

Menopause: Why Do Humans Experience It?

It has always been a mystery as to why humans go through menopause. Chimpanzees and bonobos, whom we share 99% of our DNA with, are still able to reproduce throughout their entire lifespans while humans in their latter part of their lives become infertile. What then, are the reasons for humans becoming infertile as they get older?

Recently BBC and the Atlantic has published an article that can potentially explain the cause of menopause. Menopause is actually a unique trait shared by only three species: humans, killer whales, and pilot whales. Scientists have made many predictions as to why humans may experience menopause, but these predictions end up being extremely difficult to test. One possible explanation for menopause is the Grandmother Hypothesis. The Grandmother Hypothesis suggests that humans have given up their reproductive potential to focus more on caring for their children and grandchildren. In order to prove this hypothesis, we must prove that children are more likely to survive when their grandmother is present compared to when she isn’t. Dr. Lummaa from the University of Turku has published a study that shows that children are 12% more likely to survive adulthood if their grandmother is present.

Elderly Woman Image by Kawahara via Flickr

With the help of advanced technology, humans nowadays are able to live longer than ever, and women often outlive the lifespan of the female reproductive system. However scientists are still finding it. This hypothesis is near impossible to test because humans’ current fertility rate patterns are different from the fertility patterns of our ancestors.

Surprisingly, if we investigated other species that also experience menopause, we could possibly relate this information back to the human species. Darren P. Croft, an animal behaviorist at the University of Exeter, used years of data to reveal why killer whales potentially experience menopause. It became clear that from an evolutionary standpoint, it is a disadvantage for the mother and daughter killer whales to be impregnated at the same time. When both the mother and daughter killer whales reproduce during the same period, the newborns of the older generation have a higher chance of dying, approximately 1.7 times more likely as opposed to the younger generation. According to Croft, “this new research shows that old females go through the menopause because they lose out in reproductive competitive with their own daughters.” This research on killer whales provide us with an explanation for menopause that may possibly apply to humans.

Killer Whales: One of the three species that goes through menopause
image by Grit via Flickr

All in all, it remains a mystery as to why humans go through menopause. Although there are many existing hypotheses that may potentially explain menopause, nothing has been scientifically proven. However, we can gain insight into why humans experience menopause through observing other species.

-Andrew Ting