Humans Are Getting Dumber Because City Life Is Too Easy

Remember that time you, like, totally owned that Zizek thesis in art semiotics? Or that degree you got in post-reunification Germanic studies? Or how you were – no big deal, guys – a National Merit Finalist? Yeah, well, hate to break it to you Einstein, but you're probably not even as bright as humans were just a few thousand years ago, so don't rush to pat yourself on the back.

According to research by geneticist Dr. Gerald Crabtree of the eponymous Crabtree Laboratory at Stanford University, the genes that are directly responsible for our intellectual and emotional skills are basically eroding. As we speak.

But let’s backtrack for a sec. Between 2,000 and 5,000 genes out of our much larger genetic makeup serve as the building blocks that shape our superior cognitive ability. Somewhere over the course of the last 500,000 to 50,000 years, those few thousand genes were slowly refined in groups of early humans, enabling us to perform feats of mental strength like hunting and tracking game, domesticating plants and animals, and eventually, parallel parking. (For the record: I can do exactly none of these things.)

And yet, despite the rapid rise of human intelligence over a relatively short period of time in human evolution, Dr. Crabtree estimates that humans are slowly eliminating superior genetic traits, or components of traits, out of our genetic pool. In fact, he figures that within the next 120 generations, every individual in the human population will have experienced mutations of at least two genes, if not more, that are specifically related to our intellect and emotional capacity.

But as the Stanford team outlines in their paper, this decline in genetic muster is not anything new, and probably began somewhere between 5,000 and 10,000 years ago. The roots of what would become, some 100 or so generations later, gradual cognitive shortcomings likely developed in the period following human development of agrarian society, as people began to live in cities.

Crabtree argues that the thought processes demanded by hunter-gatherers’ society are, in practice, actually more demanding than those of city-dwellers. Groups who had adapted to tracking large, dangerous animals (that is, survived tracking these large, dangerous animals) passed on greater spatial reasoning skills, motor ability, and judgement than early humans who became dependent on waiting for their neighbor to harvest those fields nearby or slaughter a domesticated animal. Thus the slow, inevitable dumbing down of the human gene pool.

In simple terms, Crabtree is arguing that our gene pool now has more unintelligent genes in it because it doesn’t take as much intelligence to simply survive as it used to. But it’s a bit more complicated than that. Imagine that the height of our genetic capacity for intelligence came when we were hunter-gatherers, because, as Crabtree posits, only the very smart could have survived. Since then, mutations have appeared in our gene pool — which is a totally normal occurrence — some of which may have had a negative effect on our cognitive abilities. Because it’s easier to survive these days, those genes are more likely to persist than they did when life was tough. Basically, because we don’t need every ounce of intelligence to survive and reproduce, we’ll eventually begin to lose it.

Of course, humans also invented music, mathematics, indoor plumbing and booze over the same “dumbing down” period, so things have kind of worked out. It's also worth noting that according to Crabtree's estimates, any future mental deterioration in humans will happen incrementally over another 3,000 years or so, at which point in time he hypothesizes that we may well have the technology to "magically correct any mutation that has occurred."

And in any case, even if the effect is happening, it’s unclear to what degree it’s happening. Evolution is a slow process, and technological innovation is quick, and it might end up being a moot point. So even if you're technically a little dumber than your parents or grandparents, see what they say next time you're trying to show them how to update their iPod.