Family Ties: The Grandmother’s Hypothesis: How Mankind owes Its Success to Matriarchs | United States


The great civilizations of the world were forged contrary to the family instinct. The Chinese created an objective system for selecting officials who would place the interests of the state above those of their families; the Christian world forbids marriage to its clergy with a similar intention, and the Ottomans set up an administrative elite made up of foreign slaves who cannot pass on to their children the privileges they have acquired during their lifetime. All of this was designed to limit the tendency to put family interests above general interests.

However, these measures have had limited success. There were archbishops who fathered children, and the Ottoman janissaries eventually overturned the ban on handing over power to offspring. Family always wins, perhaps because the family instinct is so ingrained in human nature.

Children hold incredible potential, but for it to develop they need prolonged and intensive care that their parents are often unable to meet. We are addicted for many years after birth and this is likely to have encouraged some typical traits of the species. Recently, the Journal of Proceedings of the National Academy of Sciences of the United States of America (PNAS) published a study conducted by researchers at Harvard University who suggested that active grandparents promote the maintenance of physical fitness in humans long after their first reproductive years and who also explain why exercise is so beneficial later in life. life. This role of grandparents as the mainstay of parenthood could be the reason why females, unlike in virtually all other animal species, can live decades after losing their reproductive capacity.

The success of species in general is reproductive, but ours has been successful with an increase in non-breeding time

María Martinón Torres, director of Cenieh

The “grandmother’s hypothesis” was developed through the study of older women from the Hadza people of northern Tanzania. Kristen Hawkes of the University of Utah observed that these women were extremely active in collecting food which they then shared with their daughters. This generosity made it possible to give them more grandchildren. Years later, an analysis of pre-industrial societies in Canada and Finland came to similar conclusions. At the beginning of the 17th century in Quebec, ecclesiastical registers allow us to determine that women who live in the same parish as their mother have on average 1.75 children more than their sisters who live further away. In Finland, the results showed a similar trend, as long as the grandmother was not over 75 years old.

“Natural selection would have favored the longevity of species made up of dependent individuals”, explains María Martinón Torres, director of the Spanish National Center for Research on Human Evolution (Cenieh). The fragile human babies and their huge brains would have had a better chance of survival and development thanks to their grandmothers and in turn their efforts would have given our species the reward of a much longer and healthier life than that of our close relatives, such as chimpanzees. These animals, which remain fertile throughout their lives, suffer severe physical decline in their 30s and rarely reach 40 years of age.

Paleoanthropologist Marina Lozano notes that this essential function in grandmothers is believed to have started with homo erectus, a species that appeared about 1.8 million years ago. “It is the first species of our genus to have a structure and life cycle similar to ours, with more dilated growth in which lactation and infancy are separated and we have another stage, adolescence,” explains Lozano, of the Catalan Institute of Man. Paleoecology and social evolution.

It is likely that grandmothers’ help began with a human species that predated our own, but it seems that around 50,000 years ago cultural transformations took place that intensified the phenomenon. According to calculations by Rachel Caspari, a researcher at Central Michigan University, based on the fossilized teeth of 768 individuals who have lived over the past three million years, among Homo sapiens in the Upper Paleolithic, the number of individuals surviving until an age when they could become grandparents increased considerably. During this period, for every 10 Neanderthals who died between the ages of 15 and 30, only four lived longer. Among Homo sapiens, this number increased to 20.

Sapiens were already on the planet for tens of thousands of years, but about 60,000 years ago something happened that increased their capabilities. “There is a palpable cultural sophistication; this is the time when the hybridization with the Neanderthals took place and it is also at the time when there was a migration out of Africa which coincided with migrations within the continent ”, explains Antonio Rosas, director of the paleoanthropology department of the National Museum of Natural Sciences in Madrid. “This period was unique, something was happening and it was clear that it was changing the social and cultural organization, something that would also change the value of grandparenting.”

This capacity for cultural adaptation has increased the life expectancy of Homo sapiens, leading to a greater number of grandparents in the population. Women are born with a certain number of eggs which are distributed during their fertile years. With the increase in life expectancy there may have been a change that also increased the number of eggs to maintain fertility longer, but the presence of grandmothers without their own children to raise offered other advantages. Human females are among the few animal species that cannot reproduce until the end of their life. The rest are cetaceans with teeth, such as pilot whales, beluga whales, narwhals and orcas, which also have large brains.

During this period of intensified cultural and biological transformation, greater life expectancy would have been a driving force for the species which, after several millennia of survival, was on its way to unprecedented global expansion. “The extension of life expectancy allows an overlap of generations which makes it possible to accumulate exceptional wealth. Australopiths never knew their grandparents. Being able to bring together three generations in the same household is a hive of knowledge that other species do not have. Humans don’t have to start from scratch with every generation. This completely changes the value of the elderly, ”explains Martinón Torres.

These societies, in which the grandparents take more and more importance, are at the origin of artistic creations such as the cave paintings of Altamira in Spain and Lascaux in France. They were able to improve their hunting skills and survived and prospered during the Ice Age in Europe, during which Neanderthals became extinct. This particular species, so fragile for so long, has enjoyed its success in an almost paradoxical way, explains Martinón Torres. “The success of species in general is reproductive, but ours has been successful with an increase in non-breeding time. “

The developmental needs of the brain, the organ where intelligence resides, but above all the social skills of humans, have altered other features of human biology that at the same time have reinforced the cultural changes that have transformed the planet. The contribution of grandparents to childcare was one of the defining traits of human uniqueness. As on other occasions, the strength of the species was found among some of its weakest members.


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