The Adaptive Mechanism Behind Birth Rate Decline: Is It Group Evolution?

Birth rates are falling around the world. Why? Also, what is the reproductive benefit to people having fewer children – or no children at all?

I just read an article titled “Pets in Tokyo. The Plague.” In it, the author writes scathingly about Tokyo’s obsession with pets, the replacement of children with pets (there are more pets than children in Japan), and the obscene amounts of money Japanese spend on these surrogate children, instead of simply having children.

I’ve been utterly fascinated with the rapid spread of infertility and childlessness across the globe in recent decades.

Ubiquitously, across nearly all societies, even those with completely different cultures, governmental setups, and geopolitical alignments, birth rates are in freefall.

Any birth rate under 2.1 total births per women means a declining population; and the lower the birth rate, the faster the decline. As of 2024, the average total fertility rates of the various countries and regions were as follows:

• Iran: 2.0 total births per woman
• South America: 1.8 total births per woman
• Australia: 1.8 total births per woman
• Russia: 1.8 total births per woman
• United States: 1.7 total births per woman
• Western Europe: 1.5 total births per woman
• Japan: 1.4 total births per woman
• China: 1.2 total births per woman
• South Korea: 0.8 total births per woman

North Korea, South Korea’s bitter enemy and polar opposite, is at a mere total fertility rate of 1.9 births per woman.

Even sub-Saharan Africa, that bastion of resistless procreation, has seen its fecundity slide in recent years, from 6.5 total births per woman in 1980 to a comparably meager 4.5 in 2022.

The interesting question here, though, is what is the mechanism?