Living in a big city has its perks: lots to do, easy access to transportation, cultural diversity, and so on. But the disadvantages—crime, higher taxes, and air pollution—are there as well.

No matter where you live, human evolution is still adjusting to modern living, and some experts say it’s responsible for numerous pitfalls, including the downfall of evolution of our species.

An Emotional and Intellectual Decline

Gerald Crabtree, head of a genetics lab at Stanford University, published a two-part paper in the journal Trends in Genetics that supposed that human intellect has been in decline since we invented cities and agriculture.

In essence—and in much more eloquent terms—Crabtree argued that now we’re dumber and more emotionally unstable than we were 3,000 years ago because we’ve slowed the natural selection process, allowing for abnormalities in genes to continue. 

During our hunter-gatherer days, one mistake could mean instant death, so we had to upgrade our critical thinking skills, such as understanding velocity and distance when throwing a spear at a large animal. Now that we all live in supportive societies that are much more forgiving of lapses in judgment, instant natural selection is mostly extinct, except Darwin Award nominees.

“A hunter–gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his/her progeny, whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate,” Crabtree wrote. “Clearly, extreme selection is a thing of the past.”

Thankfully, Crabtree wrote, our society is robust with education, and medical and technological advancement can solve the problems of our mental decline.

Crabtree has received plenty of criticism from fellow geneticists, including a lack of definitive proof to back up the claims, but it does give some food for thought when it comes to where humans are headed.

If there’s any wonder if we’re still evolving forward, just take a look at how modern life, namely that experienced daily by billions of people living in cities, is harming our health.

Survival Skills Are Now Learning Disorders

Before we developed modern society—which consists of boxes inside boxes inside boxes—humans needed to always be on alert for weather, predator, or prey. Those who navigated the uncharted territory the best lived the longest and passed their genes onto their offspring. And those offspring weren’t taught in classrooms, they were taught to survive by learning and doing directly.

Some research supposes that the traits that kept hunter-gatherers alive are now considered the learning disability known as attention-deficit hyperactivity disorder, or ADHD. 

Researchers from Northwestern University studied two genetically similar tribes in Kenya—one was nomadic and the other settled into villages. They examined the genetic variant DRD4 7R, which is linked to novelty seeking, greater food and drug cravings, and ADHD symptoms.

They found that the tribesmen who showed what would be classified as ADHD symptoms were better nourished than those who didn’t, supporting the hypothesis that ADHD-like qualities helped humans survive when they had to scour the landscape for food and remain stealthy as to not become a lion’s dinner.  

But now when people with those same traits are told to sit in a room for seven hours and listen to one person speak, it seems natural they might lose interest and stare out the window.

The outdoors, after all, is where they may have peaked out on the evolutionary scale.

Air Pollution, Allergies, and Stagnant Office Life

While the previously mentioned research supports theories of what happened to humans after the dawn of modern civilization, modern living continues to have its impact on our health.

For example, the overuse of fossil-fuel burning is contributing to detrimental health effects, such as hardening of the arteries and heart disease, as well as possibly increasing the risk of rare childhood cancers

And in America, there’s something that increases a person’s risk of allergies. A recent study of almost 80,000 children at St. Luke’s-Roosevelt Hospital Center in New York City found that foreign-born children have a lower risk of allergic disease, but once living in the country for a decade, that protection wears off.

There are numerous reasons to account for the increase in allergies, from over-cleanliness or overuse of antibiotics, but until we know for certain, we do know the effects of living in modern cities are affecting the human species in ways evolution has not fully adjusted for.   

While it’s unlikely we should return to scrounging for food, maybe it’s not a bad idea to spend a little time outdoors and get some fresh air.

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