HeathcareThe reason why natural selection "doesn't care as much"...

The reason why natural selection “doesn’t care as much” about women’s health


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the body of the women Modern societies seem to be the epicenter of an intense conflict of interest.

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On the one hand, there would be its reproductive capacity and, on the other, its Health.

“Many women put a lot of effort into following what they’ve been told is a healthy lifestyle. They don’t smoke, cut fatty foods out of their diets, cut back on sweets, take the stairs instead of the elevators, and walk to work “.

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“When they get breast cancer, a heart problem, or osteoporosis, they often blame themselves and ask, ‘What did I do wrong?‘” says the book. The Fragile Wisdomby biological anthropologist Grazyna Jasienska.

But the truth is that blaming yourself makes no sense.

Although, the author acknowledges, there are practices that are totally harmful and should be avoided, we should not blame ourselves for getting sick.

And it is that, he tells BBC Mundo, there are many factors that intervene in this process. For example, “it could be genetic, it could be due to some kind of interaction, an accident in our physiology.”

Jasienska is a professor at the Department of Epidemiology and Population Studies at the Jagiellonian University in Poland and is trying to understand why preventing diseases in women can be so difficult.

In the description of his book, Harvard University Press summarizes the essence of what he calls the conflict of interest in the female body:

“Women’s physiology has evolved to facilitate reproduction, not to reduce disease risk.”

For this reason, the researcher goes back several thousand years in search of answers.

a priority

“The past allows us to understand what is happening to women today in terms of health and physiology,” she says in our interview.

Our evolutionary legacy carries weight when it comes to cancer and reproduction.

“In evolutionary terms, passing genes to the next generation is always more important to be healthy,” he says.

“Of course you need to be healthy to pass them on, it’s an important part of that process, you have to survive, find a partner to reproduce,” but “whatever it is” that happens to the organism to support that transfer, it will be “more important than anything.”

For example, he explains, the chances of breast cancer in women increase in relation to “lifetime exposure to estrogens,” hormones that are extremely important for pregnancy.

“The higher that lifetime exposure, the higher the risk of breast cancer.”

“One might ask: why is natural selection, the main mechanism for evolutionary change, does not make us different to stop producing such high levels of estrogen, if estrogen is so bad for your health when it comes to breast cancer?”

The answer is direct: because estrogens help reproduction.

“It doesn’t matter what kind of harmful consequences high estrogen has for life as long as it supports gene transmission to the next generation.”

Natural selection “doesn’t care as much” about women’s health as their ability to reproduce.

“Estrogens, a group of female sex hormones, are known to be human carcinogens. Although these hormones have essential physiological functions in both women and men, they have also been associated with an increased risk of certain cancers.”

US National Cancer Institute

more menstrual cycles

The professor has investigated the dramatic change in the number of menstrual cycles.

female reproductive system

“It is estimated that in what we would call the Stone Age, women were only about 100 cycles throughout their lives.”

There is no certainty of the reason. It is believed that it is because they matured later, although it may also have influenced that they entered menopause earlier.

“The first period was much later than women experience it now, we don’t know how much later, but maybe around 16 years old.”

That variation has added a few years of menstrual cycles to the lives of women who developed at 12, 13 years old.

Also, our ancestors had more children and pregnancy and breastfeeding have an effect on periods.

This is how “modern women have about 450 cycles during life instead of 100″.

woman with a calendar

“That’s a huge difference when you think about estrogen exposure” because these hormones, which are secreted by the ovary, play a regulatory role in the menstrual cycle.

According to the professor, the way these cycles develop has also changed. For example, they have higher levels of hormone production than in the past.

“When it comes to estrogen exposure and modern life, we find that we have more cycles and of a different quality” and that translates into “greater exposure to hormones.”

“Breast cancer cells have receptors (proteins) that attach to estrogen and progesterone, which helps them grow.”

American Cancer Society

The price

“Whatever you do in life, there will be some costs associated with that. If you physiologically focus on reproduction, there will be a cost,” says the professor.

For example, the same level of energy that you dedicate to reproduction, you will not assign it to other functions of your own organism and that can cause other aspects of your health to suffer.

growth of a woman

“Because you put energy into reproduction, the immune system is going to suffer. The risk of getting infections is going to go up, and because of that, other things that the immune system is involved in are going to be affected.”

“In a way, you accumulate damage during your reproductive years because you’re in that role.

“And of course natural selection doesn’t care much about us in the post-reproductive stage.”

“Reproduction in human females is costly, in terms of energy, nutrients, and metabolic adjustments. Therefore, females who experienced high reproductive stress as a result of multiple reproductive events would be expected to age faster. However, evidence from long-term negative effects of reproduction is inconclusive.

“Many studies have documented that women with intense reproduction have an increased risk of age-related diseases“.

“In humans, as in any other species, natural selection has favored traits that are beneficial for successful reproduction, although they may not be beneficial for health, especially in old age.”

Jasienska in Costs of reproduction and aging in the human female (Costs of reproduction and aging in the human female).

The grandmother hypothesis

However, the expert raises the so-called grandmother hypothesis, which states that when women reach the stage where they cannot have more offspring, although “they cannot pass genes directly to the following generations”, in a certain way they they do by helping their children and grandchildren pass them on.

Grandmother playing with her grandson

“In that sense, one could say that natural selection doesn’t immediately kill us when we become post-productive because there is still an evolutionary sense“.

“In many species, the females live as long as they can reproduce and manage to do so until the end of their lives.”

“We can live much longer (after that stage) and there’s a lot of discussion about that from an evolutionary biology perspective.”

“Why keep us alive for so long if we can’t pass on genes, which is the evolutionary biological purpose of life?”

The grandmother hypothesis is one explanation, he says. “Perhaps women still have an evolutionary role.”

The diet of the ancestors?

The teacher believes that although cancer is also related to the modern lifestyle, there are other factors that can intervene in this disease.

The same goes for other ailments.

Woman talking to her doctor

The Fragile Wisdom raises a reality: we hear daily how different diseases can be prevented by leading a healthy life, but when we get sick, the feeling that somehow we failed in the attempt to follow what is recommended, can become overwhelming.

“What is a proper diet? Some people propose what they call the Stone Age diet,” he tells BBC Mundo.

“The Stone Age diet didn’t exist because there was a huge variety of diets depending on whether you were in a cold climate or in the desert or on the coast.”

drawing of two women

“There is the idea that if we eat the way our ancestors did, we will be healthy, slim and beautiful, but no, it doesn’t work that way because they ate many types of food and humans, in general, they evolved to eat many things“.

“I think that was something that happened in evolution: we don’t need a very particular diet to survive. We’ve evolved to eat very different things and be fine.

And that’s a wonderful thing from our past.”

Don’t look for perfection

“We’re only human, we can’t be perfect. Also, we don’t know how to be because some of the health advice often changes.”

woman exercising

And an example of them are precisely diets.

“People tell you one thing: eggs are really bad, but then a different study indicates that they are good. There is an article that says that coffee is harmful and then another that assures that it is perfect and that with three or four daily cups your health will be better.

“Many of the health messages they are very confusing“, although others are absolutely clear and proven: “if you smoke you ruin your life and then you could blame yourself”.

Trying to take care of our diet and exercising is important.

But the truth is that health is very complicated: “there are many interactions, you don’t have to try to be perfect all the time.”

“We must take care of ourselves and not only for ourselves, but for our families and friends, we do not want to be a burden to anyone.”

“It would be nice to be active and healthy in old age, but if we’re not, it doesn’t mean it’s our fault.”

“We never know if it could be genetic, it could be due to some kind of interaction, an accident in our physiology.”

“Nothing makes sense…”

Another aspect is physical activity, something in which our ancestors surpassed us.

women of three generations

“Of course physical activity is very good for health. But how much should we do? We don’t know yet. There are many organizations that will tell you three times a week, others that many minutes, some will recommend something else.”

But it depends on the requirements and health status of each person.

In some of her academic articles, Jasienska evokes the famous phrase of the Ukrainian geneticist Theodosius Dobzhansky: “Nothing makes sense in biology if it is not in the light of evolution“.

In fact, in the text Public health needs evolutionary thinkingthe researcher paraphrases her: “Nothing in demography and public health makes sense if it is not in the light of evolution.”

And it is that he believes that “we cannot really understand the functioning of any organism until we apply the evolutionary approach”.

As Laura G. Goetz indicates in an article in Yale Journal of Biology and Medicine: “As fascinating as it is educational, The Fragile Wisdom leaves as many questions as answers, in the best possible way”.


Source: Elcomercio

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