The Limited Times

Now you can see non-English news...

Why do women live longer than men?

2022-09-28T16:17:39.214Z


Experts explain the reasons why life expectancy is different according to gender. By Juan Carranza Almansa - The Conversation Women have always lived longer than men, regardless of country, culture, race or historical moment. Although life expectancy increases when living conditions improve, as has happened in many countries over the last decades, the difference between genders remains. Good living conditions make the most of our potential, but there is something structural t


By Juan Carranza Almansa -

The Conversation

Women have always lived longer than men, regardless of country, culture, race or historical moment.

Although life expectancy increases when living conditions improve, as has happened in many countries over the last decades, the difference between genders remains.

Good living conditions make the most of our potential, but there is something structural that persists that is different between genders.

Why?

To understand what living beings are like, we have two types of reasons: proximate causes and ultimate causes.

Proximate causes refer to the mechanisms that give rise to the effects we see.

For example, aging can be caused by oxidative stress in cells, shortening of telomeres, loss of the Y chromosome in many cells in the case of males, etc.

Two women embrace.Getty Images

But behind all this there is an ultimate cause, we could say "by design", and that is that the organism is prepared by natural selection for a duration that is not infinite.

And that duration is not just any, but the best to achieve what really counts in natural selection: that the genetic instructions on how to build an organism endure through the generations.

These genetic instructions remain through time thanks to reproduction.

Organisms with different reproductive strategies have different optimal longevities.

For example, a field mouse whose strategy is to produce many offspring in a few years will make more copies of its genes than one that produces one offspring per year and is designed to live for many.

And it is so, simply, because the probability of living those years is very low if we take into account the large number of predators that can end their lives at any time.

In deer, females live almost twice as long as males.

Deer couple.Getty Images

In many species, males and females have quite different reproductive strategies.

Let's forget about humans for a moment and talk about the deer, an animal that my research team has worked on for many years.

The males base their reproductive success on becoming dominant for at least a few years, since this way they will be able to cover many females in the typical harems of this polygamous species.

Females, on the other hand, only produce one offspring per year in the best of cases.

No matter how good a male is, he will not be able to remain dominant over his rivals for more than 3 or 4 years.

He is like an elite athlete at the top: a lot of glory but necessarily short.

On the contrary, to leave many offspring, females must live for many years.

Iberian deer males can live between 11 and 12 years maximum, while females exceed 20.

[Number of Cancer Deaths Declines in the United States, New Report Says]

The interesting thing is that in our studies we have found that the design in males was adjusted to that longevity compared to that of females.

Specifically, the teeth in males are smaller than their size, so they wear down sooner than in females.

Studying the evolution of deer and other species, we found that natural selection had increased the overall size of males, necessary to win competition against other males, but had not proportionally increased the size of their teeth.

For the males of these species, if they wanted to have more children, it was preferable to give everything to impregnate many females in a few years of social dominance than to live longer.

Polygamous species: larger males that age and die earlier

Polygamous species, and specifically those called polygynous (in which each male could fertilize many females), usually present sexual dimorphism, that is, different morphologies in males and females.

Many species, such as humans, in which males are larger on average than females, in addition to different sexual traits, such as deer antlers, peacock tails or beards in men, tend to also show differences between the sexes in longevity, in accordance with the degree of polygyny.

Very polygynous species such as red deer, where a male can cover dozens of females in a season, have a life expectancy difference of 8 years (40% reduction in males compared to females).

However, in humans, with an evolutionary history of moderate polygyny, the difference between men and women in longevity is approximately 7%.

The case of deer teeth is just one example of proximate cause.

In us humans, it is likely that many processes are occurring simultaneously that give rise to this difference in longevity between men and women.

FDA warns breast implants could cause cancer

Sept.

13, 202202:17

It does not matter whether or not we currently maintain the polygynous behaviors of our past.

It doesn't matter whether we retain some degree of natural selection or not in our modern world.

What we are today is the result of that evolution and its transfer throughout recent generations through phylogenetic inertia, which means that most of our genes are copied as they are to the next generation.

Organisms are designed through natural selection and only by knowing how this selection works can we understand the ultimate reason for how we are.

Source: telemundo

All news articles on 2022-09-28

You may like

News/Politics 2024-02-24T08:32:28.305Z
News/Politics 2024-02-25T05:52:27.951Z
Life/Entertain 2024-03-08T18:57:28.775Z

Trends 24h

News/Politics 2024-03-28T06:04:53.137Z

Latest

© Communities 2019 - Privacy

The information on this site is from external sources that are not under our control.
The inclusion of any links does not necessarily imply a recommendation or endorse the views expressed within them.