Can monogamy undermine intelligence?

Yes

At least over 100 generations in Drosophila melanogaster vinegar flies.

“Male cognitive performance declines in the absence of sexual selection” proclaim Brian Hollis and Tadeusz Kawecki in the title of a paper out this week in Proceedings of the Royal Society of London B.

It’s the kind of experiment I love to see done – in somebody else’s lab. Set up some populations (lines) of a fast-breeding animal. Let some lines compete for mates but impose strict life-long monogamy on the other lines. Repeat. Then, a couple of years down the line, if all goes well, measure various traits you predict will be affected by the presence (competition) or absence (monogamy) of sexual selection.

Normally, monogamous lines end up more productive. When there is no advantage to males of jostling for dominance over one another or competing frantically for female attention, the fittest males are usually those that stay alive and don’t harm the females. But in lines where males have to compete with one another, females often end up collateral damage of the robust competition between males and even the chemical warfare between their ejaculates.

But this particular paper looked at male smarts.

Put a male vinegar fly into a vial with one receptive and a few non-receptive females, and he will court them all. How quickly he realises which female he should be courting can be used as a measure of his mating savvy.

No surprises that this measure of smarts declined after 100 generations of enforced monogamy. Each monogamous line male comes from a long line of male flies who never had to decide which female to court.

But it turns out that males from monogamous lines were also much slower to learn to associate a particular smell with the likelihood of their vial being shaken (a nasty thing for a fly to endure). So, it seems there’s some kind of general decline in cognitive performance in those lines where monogamy has been enforced for 100 generations.

Sexual selection for smarts

It’s a pretty neat finding from a purely genetic and evolutionary point of view. That removing the normally hectic competition among males (by enforcing monogamy) to find, court and sometimes coerce female flies leads to the whithering of cognitive performance reveals the role of sexual competition and mate choice in the evolution of cognitive capacity.

Of course the Drosophila study says very little directly about human intelligence. It’s value – apart from the discipline-specific genetic issues it addresses – is the clean experimental evidence it provides that sexual selection can favour the evolution of cognitive performance.

But this evidence cannot help but stir human curiosity. To what extent do we owe our much-celebrated human intelligence to sexual selection?

In The Mating Mind, evolutionary psychologist Geoffrey Miller made the intriguing case that we owe much of human intelligence to the never-ending competition to out-compete our rivals in love and to find, court, keep and even manipulate potential mates. In the past decade or so, support for Miller’s hypothesis has accumulated from a variety of sources.

Does this mean we’re getting dumber?

Ever since Darwin gave us a viable process – natural selection – by which evolution occurs, some thinkers have fretted about whether people are getting dumber. In 2012 I wrote about one such argument in which Stanford geneticist Gerald R. Crabtree lamented that humanity is “almost certainly” losing its superior intellectual and emotional capacities.

Such worries seem to come from a misplaced nostalgia about the purifying nature of natural selection in the past. The idea that back-in-the-day, those of below average intelligence fell victim to lions, wolves or starvation. But modern human institutions, by mollycoddling the intellectually weak, are somehow undermining our collective genetic intelligence.

It’s the kind of argument one might expect to find in a 21st Century tabloid lamenting the rise of the welfare state. But it’s not too far from Plato either.

Coming from exactly this position, Herbert Spencer mangled Darwin’s idea of natural selection into the pithy but hopelessly wrong notion of “survival of the fittest”. When Spencer co-opted natural selection to substantiate laissez-faire capitalism and oppose the “poor laws”, he diminished evolutionary thinking in a way that it has never quite shaken.

Likewise, Francis Galton drew on the work of his cousin – Charles Darwin – to argue that governments protecting the weak and infirm thwart natural selection’s role in improving humanity. In so doing he gave us several important statistical concepts, including correlation, regression to the mean. And he extended it to suggestions for action that initiated modern eugenics, another shameful perversion of evolutionary thinking.

The idea that human intelligence is on a slippery evolutionary slope lubricated by the protections societies provide to their less fortunate or well-endowed citizens has always been a dangerous one. But while Spencerian survival of the fittest doesn’t hold as much cachet as it once did, I am still often asked by well-meaning readers whether an apparent decoupling between intelligence and reproduction is leading us up the evolutionary garden path.

The questioners seem propelled by the same intuition that had people giggling at the band Harvey Danger’s 1997 observation that “only stupid people are breeding”. It’s an impulse that fuels much of the prurient interest in and sneering about shows like Maury or Jersey Shore.

Harvey Danger’s Flagpole Sitta. Relevance? 0:57.

It would be impossible to replicate the Drosophila experiment in humans. Randomly assigning individuals to life-long total monogamy for generation after generation is a fate, once you think of it, far worse than it even sounds. Hopefully the mistakes governments made with eugenics have taken half-baked social engineering programs of this nature off the table.

Modern civilisation has – thank goodness – eliminated many of the ghastly ways in which our ancestors could die. And that has dampened natural selection on survival. But sexual selection is always happening. And much of sexual selection’s power comes from the fact that humans aren’t life-long exclusive monogamists.

People compete for status and wealth with which to attract mates, they do the most outlandish things to get noticed and they engage in the most elaborate forms of persuasion to court and seduce their mates. Either to find somebody to settle down with, or to find another, or another. These are all expressions of intelligence, and while smarts don’t always win out, they usually help.

In fact, Mark Roeder, in his new book Unnatural Selection: Why the Geeks Will Inherit the Earth, argues that the anthropocene has seen intelligence eclipse strength vigour as determinants of success. If that is the case, then sexual selection may well ensure that 100 generations – say 2,500 years – from now, humans will have evolved to be much, much smarter than they are today.

Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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Does it matter if atheists are smarter than believers?

News just in, guaranteed to stir smug nods from non-believers and incite irritation among the devout: intelligence correlates negatively with religious belief. You may have seen similar – or contradictory – reports in the past. That’s because scores of studies have asked if religiosity is associated with intelligence. But a just-published meta-analysis in Personality and Social Psychology Review considered the evidence from 63 different studies. Overall, the meta analysis establishes the existence of a “reliable negative relation between intelligence and religiosity”.

Ricky Gervais, enthusiastic atheist and lampooner of mumbo-jumbo. Smart guy. Funny too. Wikimedia commons.
Ricky Gervais, enthusiastic atheist and lampooner of mumbo-jumbo. Smart guy. Funny too. Wikimedia commons.

University of Rochester psychologists Miron Zuckerman and Jordan Silberman, together with Judtih A. Hall from Boston’s Northeastern University, gathered 80 years of published studies that estimate correlations between religious belief or behaviour (like attendance at religious services) and intelligence. By intelligence, they mean analytic intelligence, also known as the g-factor, which captures the “ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience”. Only 2 of the 63 studies found statistically significant positive correlations between religiosity and intelligence, whereas 35 showed significant negative correlations.

Intelligence linked more tightly to religious belief than religious behaviour. While some studies showed that smarter children were less likely to believe, the pattern was weakest among school-age subjects. The links grow stronger in adulthood and remained strong at older ages. Intelligence at one age also predicted religiosity some years later – an additional indication that intelligence shapes religiosity.

Here, then, is one of those thorny issues, guaranteed to stir circular discussion. It confirms what many atheists and agnostics have always felt – that the mere flexing of one’s intellectual fibres, particularly when accompanied by the scientific method, leads a great many smart people from the path of religious belief.

And yet the finding, and the very act of me writing this column, drips with confrontational implications. Does the fact that non-believers are, on average, more intelligent than believers also imply that the religious are all low-g? Or that believers are inferior?

Of course not. The ranges overlap, and many very smart people are, or profess outwardly to be, believers. And I’m sure most people know some rather dull atheists or agnostics, too.

It’s what you do with it

There’s a cringe factor at play here, too. Many people who flirt with unbelief can’t quite bring themselves to accept that the vast majority of humanity who profess a belief in one or more deities are somehow missing the obvious fact that gods don’t exist. This – the very embodiment of humanist humility – probably keeps a good chunk of non-practising folk from admitting – even to themselves – their absence of faith.

Daniel Dennett, my own favourite contemporary thinker on atheism and secularism. Wikimedia commons.
Daniel Dennett, my own favourite contemporary thinker on atheism and secularism. Wikimedia commons.

That same unwillingness to call believers dumb, even implicitly, underpins the cringe many secularists experience at the term Bright – an adjective turned into a noun by a vibrant community who organise around their naturalistic worldview. Prominent brights include atheist pin-ups Dan Dennett, Margaret Downey, and sceptic James Randi.

Richard Dawkins – another Bright – gave atheist intellectual superiority a fine point in The God Delusion. I’ve long supported Dawkins, excusing his haughtiness as old-school Oxbridge irascibility. But his clumsy recent tweets about the state of science in the contemporary Islamic societies show just how obnoxiously patronising his view of religious people has become. Perhaps those who doubt but can’t bring themselves to admit that believers are wrong or ignorant, are timid? But perhaps they are wise?

What CAN we learn

Beyond the posturing or smug self-assurances, can any good come from considering the links between intelligence and belief? I believe that it can. In understanding how those associations arise, we learn about the nature of intelligence, the nature of belief, and – just maybe – how to build a world that transcends ignorance, nepotism, exploitation and mumbo-jumbo.

Education, particularly in the sciences, tends also to diminish belief. One can see why some big religious institutions, with the most to lose from the progress of secularism, proudly foster spectacular ignorance like Kentucky’s Creation Museum. That is not to say that all religious outreach propogates ignorance, but only that many organisations – historic and contemporary- do a pretty good job of it, and seem to benefit directly as a result.

The new meta-analysis by Zuckerman, Silberman and Hall does a thoughtful job of considering the processes that might cause the association between intelligence and religiosity. They discuss three main suites of ideas, none exclusive of the others, underlying what might be quite complex dynamics:

  • Intelligent people are more likely than their peers to defy convention and conformity. This makes them resistant to religious dogma and to the social pressures that bind people together in professed belief.
  • Intelligent people adopt analytic thinking styles. Last year I posted about how a few simple exercises in analytic thinking can erode belief. Folks who score lower for g tend to rely more heavily on intuitive thinking styles, which tend to suit religious learning.
  • Religion confers on adherents benefits such as building secure social attachment, mandating self-control and building a sense of self-worth. On top of that it can provide rules by which to navigate difficult social and moral waters: monogamy, loyalty, commitment. People who do well on intelligence tests tend also to find these areas easier to navigate unaided. Nobody does so perfectly, of course, but perhaps intelligent people have less need, on average, for religious belief and practises.

That said, perhaps the high self-confidence and self-esteem that often accompany intelligence give people a confidence – often misplaced – that they can navigate life’s tricker passages without assistance, supernatural or otherwise.

As a not-entirely-on-topic treat for anyone patient enough to reach the end of this article, Tim Minchin’s animated movie, Storm, explores pseudoprofound mumbo-jumbo of all types.

This post is, as always, a mere taste of the material I’m reporting on. If this question interests you, I do recommend you get hold of the meta-analysis, which contains a very full discussion of the complex issues underpinning the religiosity-intelligence association.

Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

The Conversation

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Is human intellect on the downward slide?

Did human intellectual capacity peak 600 years before Plato? Raphael’s Scuola di Atene fresco in the Vatican, 1511. Wikimedia commons

I would wager that if an average citizen from Athens of 1000 BC were to appear suddenly among us, he or she would be among the brightest and most intellectually alive of our colleagues and companions, with a good memory, a broad range of ideas, and a clear-sighted view of important issues.

So Stanford geneticist Gerald R. Crabtree begins back-to-back Forum pieces for Trends in Genetics, entitled “Our Fragile Intellect” (Parts I and II). Crabtree’s thesis: humanity is “almost certainly” losing its superior intellectual and emotional capacities.

Crabtree doesn’t seem to be arguing for the intellectual vibrancy of the Akademia or the Lyceum. These places, and their celebrated occupants like Plato and Aristotle graced Athens only 600 years later, well beyond Crabtree’s inferred date of humanity’s intellectual zenith.

And he doesn’t confine himself to Athens. “I would also like to make this wager”, he goes on, “for the ancient inhabitants of Africa, Asia, India, or the Americas, of perhaps 2000-6000 years ago.” He’s arguing that humans – throughout the world – have been steadily losing their marbles for the last three to six millenia.

Well, Professor Crabtree, I’ll see your Athenian intellectual Titan. And I’ll raise you a bottle of 1998 St Henri and a $100 book voucher.
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