The menopause process is often viewed as a negative thing, and furthermore, from an evolutionary and survival point of view for the species, it can seem counterproductive.
However, research has been developed on this subject which has found a number of benefits for the survival of the species, given the important role that grandmothers play in the care of grandchildren.
The grandmother hypothesis is a theory that was developed 60 years ago in order to explain a number of benefits that menopause can have from an evolutionary point of view for humans and also for people. other species where gives this process, although, as far as is known so far, there are very few species in which menopause occurs.
Next, we will explain what the grandmother hypothesis is and how it developed, as well as what other species besides humans go through the menopause process.
What is the godmother’s hypothesis?
Grandmother’s hypothesis is a hypothetical hypothesis that was developed to explain the role that menopause plays in humans, from an evolutionary and survival point of view of the species, as females of the human species are among the few species that go through this process, along with some cetacean species (e.g. killer whales, beluga whales, among others). After menopause, the process by which they stop ovulating and therefore have more offspring, females of these species can live for decades.
This is why menopause is an unusual process in biology, because even mammals that share more kinship with humans do not undergo this process. Females of species in which the menopause process does not occur generally have a reduced life expectancy from the time they can no longer reproduce.because their reproductive cycle is usually as long as their lifespan.
First approach to the grandmother’s hypothesis
In 1957, George C. Williams, an American biologist, developed a theory of menopause. postulating that this biological process that women go through between 45 and 55 years old is an adaptation for them.because by living several more years they could support their daughters and sons and help care for their grandchildren. This given the fact that as a person ages they increase the chances of developing diseases and the remaining years of life decrease, and from an evolutionary point of view it would not be more appropriate to have offspring at an advanced age.
Therefore, Williams postulated that older women can contribute to the transmission of their genes in the best possible way by helping their children and grandchildren move forward, rather than continuing to have children at an age. advanced with the risks that would entail.
The Williams’ grandmother hypothesis was made as a proposition to explain human survival throughout history, something to keep in mind when understanding this theory, as currently this theory can get a little out of date. However, in the days of hunter-gatherer groups, as well as in the pre-industrial era, grandmothers could collaborate in the care of grandchildren while their parents hunter-gatherers or, later, worked.
It should be noted that this hypothesis was developed from a biological and evolutionary perspective, because today the way of life of our species has changed considerably, because the means, the quality and the life expectancy have increased, so even having an offspring or not is a choice and not a necessity to survive as a species.
Scientific support for the hypothesis
In the 1990s, the American anthropologist Kristen Hawkes investigated the importance of grandmothers in prehistoric times in favor of the evolution of the human species, postulating that the best way to perpetuate own genes, and therefore those of the species, was to accompany the girls in the care. grandchildren, so that they can flourish with a better chance of surviving.
Grandmother’s hypothesis was investigated by Hawkes through observations he made for over a decade with families in the village of Hada (Tanzania), who lived on gathering and hunting, a way of life similar to that of prehistoric times. During the study, they could see the relevance of the fact that the grandmothers collaborate in the collection of tubers while their grandchildren did not yet have enough strength to do it themselves.
It should also be noted that these assumptions were focused on distant generations, so viewed this way, the grandmother could help collect food for the grandchildren so that they could be protected at home or cared for while mother and child would seek. food, which aided the survival of the grandchildren and made it easier for her daughters to bear more grandchildren.
Based on this hypothesis, Hawkes claims that the increase in longevity in humans has been favored. thanks to the help of grandmothers to feed the grandchildren who no longer needed to breastfeed, so the grandmother was responsible for helping her with her care and feeding while mothers could have babies before.
In addition, this hypothesis is based on the conjecture that grandchildren can have a longer childhood that allows for better development into adulthood through the help of grandmothers with care and help to collect food or any kind of help they could offer the family. However, critics of this study have not failed, attributing a lack of statistical data.
Animal species in which it is encountered
When Williams developed his research on his hypothesis, it was only applied to humans. However, Subsequent studies by scientists in Canada and the UK may have corroborated this hypothesis in other species, such as killer whales..
These studies document the survival benefits of the species when grandmothers no longer have the ability to have more offspring, and it can be seen that in families where the oldest killer whale had died, the young -children survived less often than the grandmothers who are still alive. In addition, they were also able to verify that these older whales, which continued to have the ability to reproduce, were not providing the same support as those who had gone through the menopause process which provided more support.
Other studies of the Asian elephant have found that females of this older species help protect the survival of grandchildren., although they continue to reproduce.
These studies postulate that the period grandmothers experience after menopause, which is usually quite long, and can last for decades in the case of humans, is of great benefit in increasing the longevity of humans and killer whales. , as grandmothers help grandchildren survive remarkably so that remarkably makes up for not being able to have more children, all of this always seen from a purely evolutionary and survival perspective as species
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