• Posted May 1, 2025

Human Fertility Levels Need To Be Higher To Avoid Extinction

THURSDAY, May 1, 2025 (HealthDay News) — Billionaire and Tesla CEO Elon Musk has made headlines with dire warnings that declining birth rates are an “existential crisis” for humanity.

The threat might be even more dire than Musk (the father of at least 14) says, a new study argues.

The number of new births needed to maintain human population levels is higher than previously thought, researchers report.

There need to be at least 2.7 children per woman to reliably avoid long-term extinction, according to findings published April 30 in the journal PLOS One.

That’s higher than previous estimates, which held that a fertility rate of 2.1 children per woman would maintain population levels, researchers say.

However, that figure didn’t account for random differences in how many children people have, as well as changes in death rates, sex ratios and the possibility that some adults never have children, researchers said.

“A fertility rate higher than the standard replacement level is necessary to ensure sustainability of our population,” lead researcher Diane Carmeliza Cuaresma, an assistant professor at the University of the Philippines Los Baños, said in a news release.

All G7 countries have fertility rates well below either level, researchers noted — Italy at 1.29, Japan at 1.30, Canada at 1.47, Germany at 1.53, the U.K. 1.57, the U.S. at 1.66 and France at 1.79.

South Korea has the lowest fertility rate, at 0.87, and Japan’s population is projected to decline by 31% in every generation if the fertility rate stays below the replacement level, researchers added.

For the new study, researchers calculated population levels accounting for factors like the ratio of females giving birth, the number of women who don’t have children and death rates prior to reproduction.

Results also showed that if more girls are born than boys, that reduces the extinction risk among humans.

That finding jibes with a long-observed evolutionary phenomenon, that more girls than boys tend to be born under severe conditions like war, famine or plague.

Most developed countries don’t need to be immediately concerned about population levels, the study explained.

“Extinction is not an immediate issue owing to the large population size in these countries,” researchers wrote.

However, the results suggest that most family lines will vanish due to a lack of offspring.

“The present results have a profound implication from an individual perspective: The family lineages of almost all individuals are destined to go extinct, whereas very few exceptions may survive for many generations,” researchers wrote.

“Languages also face the risk of extinction, with at least 40% of more than 6,700 spoken languages in the world threatened to disappear within the next 100 years,” researchers added. “The extinction of a language results in the disappearance of a culture, art, music and oral traditions.”

More information

The U.S. Centers for Disease Control and Prevention has more on U.S. birth rate.

SOURCE: PLOS One, news release, April 30, 2025