It is often said that some family traits skip a generation, and we have some scientific evidence that this is true. But people have four grandparents. Are there any that have some evolutionary favoritism when it comes to perpetuating their traits?
The secret of longevity. Scientists have been asking for years why humans survive for a long period of time. after their reproductive agesomething that differentiates us from practically all animals, even those closest to us evolutionarily. This is especially notable since women generally live many years past menopause.
We still don’t have a clear answer to this question, but the “grandmother’s hypothesis” postulates that the reason is that the presence of these relatives represented a survival advantage for the little ones.
Evidence of the importance of grandmothers. Theories are of little use without evidence to support them, and one of the first was provided by Finnish researchers in a study published in the magazine Current Biology. In it they verified that the survival of children between 2 and 5 years old was positively correlated with the presence of grandmothers.
The researchers found that the age and general health of the grandmothers were also associated with that of the child: the older and more frail the grandmothers, the less the benefits. The results were similar whether the grandmothers were maternal or paternal, except when they were very old or in poor health.
Health status matters. This is where one of the most curious results of this study can be found: the possibility of competition. The authors postulated that grandmothers in worse condition could have a negative effect on the well-being of their grandchildren by “competing” for care, that is, since adults in good health should distribute these tasks among more people. This effect was greater in the case of paternal grandmothers, although the authors explain why.
Different forms of care. The way in which ties are established can also have a lot to do with how relationships are established in families. The idea that parents take on a harsh role in the upbringing of children, while grandparents tend more towards indulgence, is widespread. A sort of familiar good cop and bad cop that makes us see people in a different way.
And why science can have it too: a study, this one published in the magazine Proceedings of the Royal Society B analyzed the brain responses of grandmothers to images of two family generations and other control images. The team observed that the brain response was more pronounced with grandchildren even with the children.
Environment and genetics. Not everything depends on care. Genetics matter too. One of the most obvious reasons is the possible presence of certain diseases that can manifest in the first years of life, many of which may have a genetic origin.
This is where we can find a curious fact brought to light by biostatistics. Clarice R. Weinberg through an article published in the magazine American Journal of Human Genetics. In it he reported a curious anomaly with respect to what genetics predicted, and it was a greater matrilineal genetic contribution.
The explanation given in the article was the transfer of phenotypes between mother and offspring during the nine months of pregnancy. Therefore, the genetic imprint of the maternal grandmothers would be greater than that left by the rest of the ancestors. Although the difference is not great, the effects can be great when it concerns diseases related to genetics, some of them serious.
Matrilineal inheritance. Matrilineal genetic inheritance has greatly helped scientific development, in this case thanks to mitochondrial DNA. Mitochondrial DNA, which is transmitted solely and exclusively through the mother, has allowed us to solve the most varied mysteries, from crimes until the death of the cave bearand of course, it has helped us better understand our origins.
Each family, a world. Tolstoy began his Anna Karenina by saying the famous phrase: “All happy families are similar to each other, but each unhappy family is unhappy in its own way.” It will surely fall short because surely every happy family is also a world. This implies that differences can be large from one family unit to another, but also between countries and regions and between periods. It is difficult to know what will the relationships be like? between alternate generations in the future, but at least we are getting a better idea of the bases of this relationship.
Image | Ekaterina Shakharova
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