Conservative Fertility Advantage: Natural Selection, Cultural Evolution, or Both? By Mrs. Vera West & Brian Simpson
A new study published in Evolutionary Psychological Science analysed data from over 78,000 people across 72 countries and found a consistent pattern: individuals holding more conservative social attitudes — Right-wing ideology, lower support for gender equality, higher religiosity, and preference for religious partners — tend to have more children. The effect was stronger among women.
This aligns with broader evidence. Conservatives and religious people reliably out-reproduce liberals and seculars in modern societies. In the U.S., for example, completed fertility is higher among conservative women, and gaps persist even controlling for education and income to some degree. Similar patterns appear in Europe and elsewhere. A book like Eric Kaufmann's Shall the Religious Inherit the Earth? makes the broader case: higher fertility among the religious (who skew conservative on social issues) drives long-term demographic and cultural shifts away from secular materialism.
The question follows naturally: Could this differential fertility act like natural (or cultural) selection against the political/cultural Left over generations?
The Mechanism: Fertility Gaps are Real and PersistentFertility is a direct measure of evolutionary fitness in the classical sense. Groups or individuals with more surviving offspring pass on their genes and cultural values more effectively. Political attitudes have moderate heritability (often estimated 40-60% from twin studies), influenced by personality traits like openness to experience (liberals score higher) and conscientiousness/orderliness (conservatives score higher). Religiosity is also heritable and strongly tied to fertility.
If conservatives average even 0.3–0.6 more children per woman (a common gap in developed nations), and this persists, their share of the population grows over time — especially as secular/liberal fertility often falls below replacement (around 2.1). This isn't speculation:
Religious fundamentalists and traditionalists have the highest fertility worldwide.
Urban, educated, secular populations (disproportionately Left-leaning) delay or forgo children.
Second- and third-generation effects compound: children of larger conservative families inherit both genes and upbringing tilted toward those values.
Over decades or centuries, this tilts the cultural mean rightward on family, gender, and tradition issues — even if individual conversion happens. Societies don't stay static; demography is destiny to a meaningful extent.
Natural Selection, Cultural Transmission, or Gene-Culture Coevolution?Pure genetic natural selection on political views is slow because:
Heritability isn't 100%.
Mate choice, education, media, and peers exert huge environmental influence.
Left-leaning societies can (and do) import migrants or use policy to offset trends.
But cultural evolution is faster. Ideas, norms, and lifestyles spread vertically (parent to child) and horizontally. High-fertility subcultures — Amish, Orthodox Jews, traditional Catholics, certain Muslim communities — expand their influence disproportionately. Kaufmann's book documents how religious fertility is reshaping Europe and the West, often toward more conservative social attitudes despite secular dominance in elite institutions.
This isn't "selection against the Left" in a crude Darwinian cull. It's differential reproduction reshaping the population's centre of gravity. Liberals can respond by having more kids, promoting pronatalist policies, or successfully assimilating/converting others. Many on the Left already worry about this (hence pronatalist stirrings in some circles). But ignoring the pattern doesn't make it vanish.
Counterpoints
Education and urbanization (correlated with liberalism) suppress fertility across the board.
Some high-IQ/liberal traits may correlate with other advantages (innovation, delayed gratification) that benefit society even if family sizes are smaller.
Political labels shift: today's "Left" or "Right" isn't fixed. Classical liberals might look conservative by modern standards.
Dysgenics fears (smarter people having fewer kids) are debated; recent genetic studies don't show strong, consistent negative selection on intelligence.
Long-Term ImplicationsYes, sustained gaps could lead to more conservative-leaning populations over generations, particularly on family formation, gender roles, and religiosity. This is already visible in Israel (religious vs. secular Jews), parts of Europe with high Muslim immigration/fertility, and U.S. red states vs. blue. Ancient patterns echo this: high-fertility traditional groups often outlast low-fertility cosmopolitan elites (see late Rome or certain Greek city-states).
For the Left, low birth rates among the highly educated secular core pose a genuine challenge if the goal is long-term cultural dominance. Materialist, individualistic worldviews that de-emphasize family and transcendence often come with sub-replacement fertility. Religious/traditional worldviews that prioritise it do not.
The study and supporting literature don't prove inevitable victory for conservatism — societies adapt, technology (e.g., artificial wombs, policy incentives) could change the game, and Left-leaning values spread culturally even as demographics shift. But ignoring biology and demography is foolish. Humans are not blank slates; reproduction is not infinitely malleable by ideology.
Bottom line: Differential fertility is real. It acts as a slow evolutionary and cultural filter. Conservatives' higher birth rates aren't a conspiracy — they're a feature of values that emphasise family. Whether this "selects against the Left" depends on how the Left responds. History suggests groups that fail to reproduce at replacement eventually lose influence. Demography may not be everything, but it's close.
https://link.springer.com/article/10.1007/s40806-026-00476-4
