A Cambridge University genetics researcher recently developed a mathematical model revealing why religious people stand a better chance of inheriting the earth.
British Economics professor emeritus Robert Rowthorn, in a report recently published in "Proceedings of the Royal Society B," examined the likely evolutionary outcome of a strong combination of traits among the God-fearing.
Past research has indicated that people of faith carry "a religiosity gene" - an inheritable predisposition toward religious belief. Rowthorn wrote they also widely participate in a genetically advantageous cultural practice: They have more children than the nonreligious.
This, Rowthorn concluded, will cause the religiosity gene, or combination of genes - as well as religion itself - to spread more widely.
"Provided (that) people with a religious allegiance mate mainly with people like themselves," he said, "the religiosity gene will eventually predominate despite a high rate of defection" - people losing their religion during adulthood.
Rowthorn contended that scientists widely agree that religion has biological foundations. Belief in the supernatural, obedience to authority, and affinity for ceremony and ritual depend on genetically based features of the human brain, he wrote, citing several influential studies.
"For religion to influence genetic evolution, it must convey some kind of selective advantage," Rowthorn wrote. "Such an effect might come through social bonding via ritual, formation of group identity through myth, honest signaling through participation in costly ceremonies and adherence to social norms through love or fear of God."
And, in modern times, religious people - of all income and education levels - on average reproduce more.
"The more devout people are, the more children they are likely to have," Rowthorn said.
The World Values Survey of 82 countries between 1981 and 2004 found adults who attend worship services more than once a week averaged 2.5 children, compared with 1.67 children for those who never attend. Rowthorn noted that sects such as the Amish and ultra-orthodox Jews have fertility rates three to four times greater than the secular average.
Global birth rates have fallen dramatically in modern times. In Japan and most of Europe, where societies are increasingly secular, rates are now well below parent-replacement levels. But the transition to lower fertility rates has been much slower and less complete among the religious.
Even if most of the children from high-fertility groups leave their faith traditions because of its demands or because of competing cultural values, their defections will only serve to spread the group's genes into the surrounding population, Rowthorn said.