Cultural Evolution Outpaces Genetic Evolution

Abstract: This article explores why the human brain still struggles to adapt to modern life despite centuries of advancement. It argues that our biological evolution is too slow to keep pace, as human bodies and brains were shaped for hunter-gatherer life and haven't had enough generations to fully adapt to post-industrial society.

People often say that the human brain is wired for life on the African savannah and not well-suited to modern society. But if we’ve left the savannah so long ago, why haven’t we evolved to adapt to today’s world? When will we?

In my view, our brains and bodily systems were indeed designed for life on the savannah. The most obvious sign is that we often do things we clearly shouldn’t—things that can be described as irrational.

Take sugar, for example. The human body doesn’t need that much of it, and consuming too much causes all sorts of problems. If our bodies were truly adapted to modern life, we’d get a signal after consuming just a small amount of sugar—enough to meet our needs—telling us, “I don’t want any more,” just like how appetite is regulated. But that’s not what happens. We simply love eating sugar.

Or take our craving for fresh information. Celebrity divorce news from across the world has no practical value to us. If we were truly adapted to modern life, we’d find such information boring—but instead, we consume it eagerly.

Our tendency to do these unhelpful or even harmful things is a legacy of savannah life. Back then, sugar was extremely rare, so evolution only gave us a “crave sugar” mechanism. There was never a chance to evolve a “stop craving sugar” mechanism. People also lived in small groups where nothing new happened for long stretches—any fresh information might signal an important opportunity, so it made sense to pay attention.

This is the foundation of evolutionary psychology, a well-established discipline with robust evidence.

So, if we’ve left the savannah so long ago, why haven’t we evolved to better fit modern life?

The key is: we haven’t actually been off the savannah that long.

The structure of the Homo sapiens body and brain was fixed around 200,000–300,000 years ago. For nearly all of that time, humans lived as hunter-gatherers. Agriculture only emerged about 10,000 years ago, and it didn’t immediately bring prosperity. True abundance only began with the Industrial Revolution, a mere 200–300 years ago. And widespread food security for most people is only a few decades old.

That’s not enough time. Natural selection alters genes through reproduction. Humans reproduce roughly every 20 years, making genetic evolution extremely slow.

And yet, interestingly, humans have still evolved in the past 10,000 years.

Take resistance to diseases like malaria. Outbreaks of infectious diseases killed many people quickly. So if someone happened to have a genetic mutation that provided resistance, they had a much greater chance of passing their genes on. Today, a significant portion of the population has inherited such resistance—they’re the descendants of survivors.

Another example is the Tibetan Plateau. If someone from northeastern China moved there, they would struggle with altitude sickness and possible health risks. So how do Tibetans manage? Because they too are the descendants of survivors. Humans have only lived on the plateau for a few thousand years. When their ancestors first arrived, they surely suffered from altitude sickness too. Only those with genes that allowed them to cope survived and reproduced.

One of the most extensively studied examples is lactose tolerance.

Originally, all mammals—including humans—only consumed milk during infancy, and only from their mothers. Milk’s main energy source is lactose, which requires the enzyme lactase to digest. Mammals typically stop producing lactase after weaning, making most adults lactose intolerant—they suffer digestive discomfort or diarrhea when drinking milk, absorbing little nutrition.

This was universal—until humans invented animal husbandry. Suddenly, even adults had access to cow or goat milk. In times of food scarcity, the ability to digest milk became a survival advantage. As a result, people with rare mutations allowing them to continue producing lactase into adulthood had a better chance of surviving and reproducing.

Scientists found that this lactose-tolerant gene mutation first appeared about 7,000–9,000 years ago. It arose independently in Europe, the Middle East, and East Africa. In just a few hundred generations—less than 7,000 years—this gene became widespread.

So not only has human evolution not stopped, but thanks to lifestyle shifts like animal farming, evolution can even accelerate. This is known as cultural-gene coevolution.

Then you might ask, if that’s the case, can we deliberately accelerate evolution so that our bodies and minds become better suited to modern life?

…Not quite.

The key point is: evolution is an extremely brutal form of selection. For a gene to spread rapidly, not only must its carriers reproduce more—it also means those without the gene must die out. That kind of selective pressure is incompatible with modern ethics.

In fact, today’s reality is the opposite.

The people who are most adapted to modern life—those with high income and education levels—tend to have fewer children. Meanwhile, those with lower income and education levels, and lifestyles more aligned with traditional ways, tend to have more children. If you follow that logic, it would seem humanity is undergoing “reverse natural selection”—those living closer to the primitive way of life are more likely to leave descendants in the modern world.

Is that frightening? Perhaps not.

The crucial difference is that modern life isn’t passed on through genes anymore—it’s passed on through memes, or cultural genes. Our lifestyles and values are spread not by bloodline, but by knowledge transmission.

Yes, people in some underdeveloped regions are having lots of children, while East Asians are too busy studying to reproduce. But that doesn’t mean the future world will be overrun by people who only want to have kids and not study. As long as learning really improves life, kids in underdeveloped regions will want to study too.

Cultural evolution is much faster than genetic evolution. The Chinese imperial examination system shaped an entire culture of scholarly pursuit in just over a thousand years—resulting in a society where “everyone loves learning.”

So if you believe in the power of culture, you should be deeply optimistic about humanity’s future. Newton never married and had no children—but we are all his spiritual descendants.