Scientists have issued a stark warning that the 'greatest risk to the future of civilisation' could trigger societal collapse within two decades. The new study challenges previous assumptions about replacement fertility rates, suggesting the threshold is higher than once thought.
Fertility rates falling below replacement levels
Elon Musk has long described declining birth rates as the 'greatest risk to the future of civilisation.' Currently, the US fertility rate stands at 1.62, while the UK is even lower at 1.57. Research indicates nations need a fertility rate of 2.7 children per woman to maintain population growth, up from the earlier estimate of 2.1.
Why the threshold has changed
The research team argued that the initial calculation did not properly account for factors such as death rates, gender balance, childlessness, and random variations in family size. Diane Cuaresma, one of the study's authors, stated: 'Considering stochasticity [unpredictability] in fertility and mortality rates, and sex ratios, a fertility rate higher than the standard replacement level is necessary to ensure sustainability of our population.'
Consequences of underpopulation
Musk has warned that declining birthrates would lead to fewer workers, mounting debt, overstretched healthcare and pension systems, and could spark complete social chaos. The researchers published their findings in the journal Plos One, noting that 'the underpopulation crisis has been a serious threat to the sustainability of developed countries.'
Global and regional trends
The worldwide total fertility rate has dropped from 5.3 in the 1960s to 2.3 in 2023. The Republic of Korea now has the lowest rate at 0.87, attributed to high living costs and workplace pressures. In the UK, birth rates have fallen dramatically, with some boroughs seeing a 60% drop in women having children since 2013.
