P.why moving is so important when you become an adult, have you ever wondered? Because being sedentary increases the risk of a slew of diseaseswhile keeping fit slows down the deterioration of the body and brain?
Researchers have discovered various biological processes that they describe “How” physical activity is good for youbut they also try to explain the “Why” this movement-health association is written in our genes, what is the meaning in the light of evolution which, as is well known, tends to favor the most suitable characteristics for the survival of the species. It will be said: we descended from primates, climbed trees and ran to get food. Still, motion appears to have greater repercussions on human well-being than that of apes. Some American scientists therefore found another, suggestive link to explain the weight of exercise on longevity and set it up in a theory which they called the “Active Grandparents Hypothesis”.
The hypothesis of active grandparents
The idea was described in an article that appeared in the scientific journal PNAS (Proceedings of the National Academy of Sciences). In summary, in the course of evolution they would have been selected those individuals who lived several decades after ceasing to reproduce (which would not make sense per se for the species), but who were also moderately active during those post-reproductive years. And this to be able to provide sustenance for the descendants.
Grandparents and grandchildren (Getty images)
Active grandparents would be the true pillars of civilization, the saviors of mankind. Made healthy and long-lived by physical activity, the prehistoric ancestors were able to take care of their grandchildren, helping their parents. Once, like today, they were the “social safety nets” par excellence of a young family.
Daniel Lieberman, evolutionary biologist Harvard University and lead author of the PNAS editorial, began his reflections on the discovery that wild monkeys move less than an average American adult, who takes about 4,700 steps a day, and far fewer than the Hadza of Tanzania, modern hunter-gatherers who walk about 15,800 steps each day and collectively engage in more than two hours of moderate to vigorous physical activity. THE primates, despite their relative laziness, rarely develop the typical human inactivity disorders and manage to stay healthy. On the other hand, they generally have a shorter lifespan (contrary to popular belief, there are hunter-gatherers who reach 70 years of age).
The characteristic of the centenarians: to move
Lieberman and his team rewind the tape of the ages back and frame deductions. Our predecessors had to continually go in search of food and, therefore, those who ran and climbed were more likely to survive. When they were quite a few years old on their backs, they took care of their grandchildren, continuing to procure food for themselves and the little ones in the woods or by the sea. We could say that exercise is so good for adults because in prehistoric times there was a need for vigorous and capable grandparents and grandmothers to move to hunt prey and collect berries, in order to support the descendants. Just look at the centenarians of Japan or Cilento: one of the secrets of their longevity is working in the fields, walking, playing a role in the family context and in the community.
More years in health
Physical activity triggers a cascade of effects that stave off obesity and strengthen us. It’s kind of a stress. It causes minor muscle injuries and strains blood vessels and organs. In response, our body initiates a series of repair mechanisms. “It’s like you spill the coffee, clean it up and the floor ends up being cleaner than before,” Lieberman told The New York Times. “This reaction is probably even more significant as we become adults. Without exercise and its repairs, aging human bodies function less well. ‘ We wear out and cannot take care of our grandchildren or ourselves. “The lack of exercise explains why there is a difference between the length of human life and the length of health, between how many years we live and how many of those years we remain in good health,” continues Lieberman. “At one time the two phases corresponded. In the Stone Age, an inactive human being would probably have died soon, which is not the case today thanks to drugs and environmental conditions. But our genetic inheritance takes practice: with retirement, now is no time to slow down“. The number of years in good health in Italy is 73.2, which is almost ten less than life expectancy (data from World Health Organization, Who, 2016). Ten years of ailments.
Doctors prescribe exercise
In his latest book, ExercisedLieberman notes that humans evolved to walk, run, dig, and perform other physical activities when they were needed and rewarding, but otherwise they rested and avoided unnecessary effort. Here’s why, given the choice, so many people stay on the sofa. However, since increasingly sedentary lifestyles contribute tosoaring rates of obesity and diseases such as diabetes, explains the author, we should medicalize exercise. Prescribe it as if it were a pill and at the same time entice the elderly to enjoyable activities, for example the dance or the walks in the green. The Active Grandparents Hypothesis is just a theory and perhaps it will be impossible to prove it. Some experts have criticized. The first is that physical activity improves health in other species as well, like mice. The second perplexity concerns the lack of distinction between genders: grandparents can procreate while grandmothers cannot and therefore the roles in extended families may have been different.
Only the woman and the orca go through menopause
In this regard, it should be remembered an article from 1998, also on PNAS, whose main author, the American anthropologist Kristen Hawkesalready proposed the thesis that women lived well beyond menopause to ensure the success of subsequent generations. The Grandmother’s Theoryaccepted by the majority of anthropologists, arises as an answer to a question: why does the woman of our species go through menopause while the male specimen of Sapiens sometimes remains fruitful even at 70 years of age and beyond? It is an unsolved puzzle of evolution: she appears to be the only female among mammals, along with the killer whales and chimpanzees in captivity. Hawkes’ idea is shared by many and the geneticist Luca Cavalli Sforzain the essay Why science (Mondadori), explains that women, with the end of fertility, “he can more easily dedicate his business to his own children’s childrenthat is, to be a good grandmother, more than if she went on to have children herself ». It is an interpretation.
Another theory, developed by Canadian researchers (appeared in PLOS Computational Biology in 2013), it attributes to men the origin of a chain of genetic mutations: eager to become fathers, since the dawn of time they would have preferred young women, making the possibility of pregnancy useless for their peers. It remains a mystery and in any case it is too late to protest.
Eliana Liotta (photo by Carlo Furgeri Gilbert).
Eliana Liotta is a journalist, writer and science writer. On iodonna.it and on the main platforms (Spreaker, Spotify, Apple Podcast and Google Podcast) you will find his podcast series The good that I want.
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