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Does Conservative Religiousness Promote Selection for Intelligence? An Analysis of the Vietnam Experience Study
Edward Dutton and Emil O. W. Kirkegaard
Published: 2024/03/01
Abstract
Previous research has indicated that religiousness may moderate the negative effect of intelligence on fertility which is found in modern populations. We studied this question using the Vietnam Experience Study, a public dataset of 4,462 American Vietnam-era veterans. In line with prior research, we found that, net of controls, intelligence predicted lower fertility, [I]β[/I] = -0.06 ([I]p[/I] = .003), and religiousness predicted higher fertility [I]β[/I] = 0.21 ([I]p[/I] < .001). The expected interaction, intelligence * religiousness, was also found ([I]β[/I] = 0.06 ([I]p[/I] = .002). The results show that above average religiousness is associated with a neutral or positive fertility pattern regarding intelligence, while average or below average religiousness is associated with a negative fertility pattern. The results held when the White subsample was analyzed separately (intelligence · religiousness [I]β[/I] = 0.09 [I]p[/I] < .001). Finally, the negative relationship between intelligence and fertility seen in the dataset showed a strong Jensen Effect in the expected direction ([I]n[/I] = 19 tests, [I]r[/I] = −.73). Keywords: Vietnam Experience Study, Intelligence, Fertility
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