Can we say anything about human beings to come? In a word, yes.
Recently after lecturing about human evolution, I had a student come up to me and ask—she apologized first, as some do, despite my mantra that there are no bad questions—if I had any thoughts about future evolution. I did, although I hesitated to offer them; the political correctness monitors are everywhere in universities today. But, casting caution to the winds,
I said what I actually think.
“In the future the species will be more brown and more religious.” She and another young woman with her—both were brownish, smart and pretty—looked bemused, as they were supposed to, and after a pause for drama I explained.
More brown is a no-brainer, for two reasons. First, the species (very fortunately I think) has an unprecedented and rising rate of interracial mating, whether through marriage or other unions. In the U.S., for example, it’s the one measure of improving race relations that has undeniably and steadily risen since the ‘sixties.
Unless that trend reverses, then over the millennia to come global travel and communications can only further reduce the race and ethnic differences that have so long kept gene flow relatively low. No doubt there will always be some people we would still call black, white, red, or yellow, but there will almost certainly be ever-more of us in between.
Second, white people, or Europeans and their descendants, are no longer replacing themselves, and Asians are headed the same way. China may have imposed the one-child family, but Thailand and Italy chose it, and such societies as Japan, Germany and France must import people or fade away. So natural selection will add to healthy mingling in making the species deliciously caramel.
But more religious? Surely this is a cultural feature that could be unpredictably and quickly swept away by a surge of faithlessness or reason?
I don’t think so. First of all, it’s been an inherent part of our species—every culture has had it—since the beginning. True, since then too there have always been unbelievers, but they have been in the minority; not as small a minority as those who came out and said it, but a minority.
So faith is durable. In the early twentieth century it seemed as if Marxist, Freudian, and analytic philosophies were all creating post-religious cultures. None lasted, although in some countries the minorities certainly grew. Today, Western Europeans are about one-third non-believers, one-third traditional, and one-third people of informal or unconventional faith.
But Western Europe is (see above) not replacing itself, and in every major religion the more religious people—especially the fundamentalists—have lots of children. Still, this is cultural, is it not? Education and media can easily bring the European pattern to the world, and eventually reduce religiosity even further. Or can they?
The famous Minnesota Twin Study found that the contribution of genes to the variation in religiosity is about 50%. If this is right, then the opportunity for natural selection is great. Over thousands of generations, even much lower levels of heritability can form a good substrate for evolution.
Levels of heritability for religiosity have varied a lot in different studies, but they may vary according to a pattern. One recent study estimated that the heritability for this measure was 12% in adolescents but 44% in adults, with most of the difference due to shared family environment. How do we interpret this?
It seems reasonable that family environment would cause twins and other siblings to behave and even think in similar ways when they are still responding to parental demands and frameworks. But in adulthood, when they are free to make their own choices, family influence may wane as they tend toward their individual choices.
Under this assumption, we would expect non-identical twins to diverge more as this happens, resulting in a marked increase in estimated heritability to a level that could lead to evolutionary change.
Of course, cultural evolution can be much more rapid than genetic evolution. But I see little evidence that cultural evolution is producing a decrease in religiosity on a global scale; quite the contrary. True, if the world sees a substantial rise in creature comforts for the whole species over the next few millennia, then we could see across-the-board declines in religiosity as well as in population—both in my view positive things.
But more likely in that time frame will be a process of gene-culture coevolution in which much larger family sizes will expand the population base of those genetically inclined to be religious, and at the same time cultural factors will fail to persuade them against that tendency and may even reinforce it.
Of course, stuff can happen—an asteroid impact, worldwide wars over fresh water, or catastrophic human-induced global warming—to change things so much that all bets are off. But in the absence of such drama, it’s likely that several thousand years from now the species will be more religious than it is today, and in general a very pleasant range of shades of brown.