Japan has found the number of children per woman to avoid demographic extinction. Two thirds of the planet are very far

A group of researchers in Japan He started studying What number of children by women could be understood as a key to “avoid extinction”, understanding this, not as prevention before a total apocalypse of our civilization, but as the prevention of statistical extinction of the lineages or family lines over time. They found two things: that the number that was presupposed above was very low, and that a large part of the population is late.

Beyond the threshold. For decades, the magic number to keep the human population “stable” It has been 2.1: It was believed that, on average, each woman should have just over two children to ensure The generational replacement and avoid population decline.

However, a New study warns that this threshold is outdated and insufficient. According to Japanese researchers, the true level of fertility necessary to guarantee the long -term survival of a human population is not 2.1, but of 2.7 children per woman.

The reasons? This adjustment is due to the fact that the traditional calculation does not contemplate the Stochastic variability (that is, randomness) in factors such as individual fertility, mortality, sex proportions at birth and the probability that some people simply never have offspring.

By incorporating these real fluctuations into population mathematical models (through Galton-Watson Model), The authors concluded that a higher rate is needed for Avoid progressive extinction of family lineages in generations of the future, especially in societies with low sustained birth.

Ignored warning. The finding is especially alarming because currently two thirds of the population World Cup lives in countries with fertility rates below the old 2.1 threshold, and well below the new estimated 2.7. Among the most affected, many highly developed, are South Korea (0.87), Italy (1.29), Japan (1.30), Canada (1.47), Germany (1.53), United Kingdom (1.57), France (1.79) or the United States, with a rate of just 1.6 children per woman.

These levels, which have remained low for decades, mean that almost all family lines in these countries are intended, statistically, to extinguish at some point in the future. Plus: The study clarifies that A slight bias Towards female births (that is, a slightly greater proportion of girls than boys) could marginally decrease the risk of extinction, increasing the probability of reproduction in future generations. But even that factor, by itself, would not be enough to compensate for a persistently low fertility rate.

Pronatalists Interestingly, this information reinforces the alarms that have sounded from certain sectors concerned about the future demographic. One of the most visible faces of pronatalism contemporary It’s Elon Muskwho has repeatedly warned that the low birth rates “will end civilization” and whose prolific paternity (at least 11 known children) is presented as a deliberate act in this fear.

For pronatalists, raising birth rate is a Existential priority. However, this position is not widely shared by the general population.

Social realism. Fortune told that a Population Connection survey carried out at the beginning of the year showed that most people do not consider low birth rate An urgent problem.

Only 15% perceived it as one of the main global challenges, while 45% expressed more concern about excessive population growth, given the fear that children are born in poverty conditions or with exhausted natural resources.

More perceptions. Another more recent survey, Made by Yahoo News and Yougov revealed that only 8% of Americans were “very concerned” about the fall in the country’s birth rate, and only 32% expressed any degree of concern about it.

In the background, another reality that We have been counting: a majority of those who do not have children, or have few, do not do it for apathy towards the future of humanity, but For practical reasons: The lack of institutional support, the loss of life, the high cost of parenting or the perception that the world is not a conducive place to form large families, they are also key. In addition, it generates an increasingly acute contrast between the demographic predictions of experts and the immediate priorities of the population.

So? The warning of Japanese researchers seems clear: without a change of course, demographic extinction will be slow but inevitable in many regions of the world. And although the term “extinction” may sound apocalyptic, what is at stake, according to scientists, is not the sudden disappearance of the human species, but the progressive erosion of family and cultural continuity, in a process where future generations will be more scarce, more isolated and, in many cases, non -existent.

From that prism, reproducing is more conditioned than ever to social, economic and environmental factors, and the figure of 2.7 children per woman may seem more a demographic utopia than an attainable objective. It does not seem that we are going to extinguish in the short term, at least not through “fertility”, but The study It puts the focus on the population growth to which many regions point out.

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