As human evolution slows down and technology speeds up, researchers say our biology is struggling to keep up. Many of the stress-related health problems we face today aren't personal failures or just modern inconveniences – they're the expected result of forcing Stone Age bodies into a world they were never designed for.

A new study from University of Zurich researchers has looked at whether the rapid environmental changes of our current era have harmed the fitness of humans. In simpler terms: they wanted to know if the world most of us live in daily is having a serious impact on our mental and physical health as a species.

By combining data about industrialization, city living, and health, the researchers argue that there are many signs that humans haven't had time to adapt to the quick changes in the world over the last century. They point to falling global birth rates, rising chronic inflammatory diseases, and other long-term health trends as signs that we've been struggling on Earth since the Industrial Revolution.

One example they give is our rapid change from hunter-gatherer societies, where humans faced occasional dangers in the wild, to urban environments where daily challenges keep us in a constant high-alert mode. City noise, air and light pollution, microplastics, pesticides, artificial light, processed foods, sitting all day, and sensory overload are all relatively new experiences for humans.

"In our ancestral environments, we were well adapted to deal with acute stress to avoid or fight predators," explained Colin Shaw, head of the Human Evolutionary EcoPhysiology research group at the University of Zurich. "The lion would come around occasionally, and you had to be ready to defend yourself – or run. The key is that the lion goes away again."

Now, we get little break from an attack of stressors – traffic, work, social media, constant sensory stimulation – that trigger those same ancestral biological responses, except without an "off" switch.

"Our body reacts as though all these stressors were lions," said Daniel Longman, Shaw's colleague. "Whether it's a difficult conversation with your boss or traffic noise, your stress response system is still the same as if you were facing lion after lion. As a result, you have a very powerful response from your nervous system, but no recovery."

Many studies have looked at how this constant buzz of elevated stress affects connected hormone systems, which has been linked to anxiety disorders, the development of chronic diseases, and reduced life expectancy.

"There's a paradox where, on the one hand, we've created tremendous wealth, comfort and health care for a lot of people on the planet," Shaw added, "but on the other hand, some of these industrial achievements are having harmful effects on our immune, thinking, physical and reproductive functions."

While it's still debated, the researchers also mention studies into an ongoing global decline in sperm count and movement, which has been linked to a range of factors – from obesity to environmental dangers like pesticides and microplastics.

"You could argue that what we're seeing today is a form of natural selection," Shaw said. "But letting chronic stress kill people for hundreds of generations until we evolve resistance is clearly not a solution."

While this is all fairly depressing, and not all chronic conditions and mental health issues are due to environmental influences, the researchers believe this work can go a long way in improving lives. And recent studies using advanced genetic analysis suggest we're actually adapting – if not evolving – much faster than scientists previously thought.

"It shows the flexibility of the human genome," says Karin Broberg of the Karolinska Institute in Sweden, who studies genetics and environmental toxins. "We've spread throughout the world, and we live in very extreme environments, and we're able to make them our homes. We are like rats or cockroaches – extremely adaptable."

We do, however, have brains that are far more complex than insects and rodents, which Shaw points out is part of the problem – it's a fascinating case study for evolutionary biologists, but not so practical or helpful when it comes to our relatively short time on Earth.

"Biological adaptation is very slow," he said. "Longer-term genetic adaptations are multigenerational – tens to hundreds of thousands of years."

So, what can we do to reduce the toll the world around us takes on our health? The researchers believe we need to change our relationship with nature – to consider it as an important health intervention – and focus on building more sustainable environments. This might be easier said than done, given the world's population and ever-growing demand on natural resources. Not to mention our species' endless appetite for making money at the expense of the natural environment. Change, says Shaw, requires both cultural and environmental solutions.

"One approach is to fundamentally rethink our relationship with nature – treating it as a key health factor and protecting or regenerating spaces that look like those from our hunter-gatherer past," he said. "Our research can identify which stimuli most affect blood pressure, heart rate or immune function, for example, and pass that knowledge on to decision-makers.

"We need to get our cities right – and at the same time regenerate, value and spend more time in natural spaces," he added.

"As an evolutionary anthropologist, my earlier work focused on Neanderthals and bone adaptation, which was fascinating in its own right," Shaw said. "But the challenges we face today feel more urgent. Those with the resources – financial or intellectual – have a responsibility to invest them in solving these problems. To me, it's a moral imperative to do the right thing."

At the very least, the researchers note, we should consider getting out into nature as valuable treatment for our health and wellbeing.

The research was published in the journal Biology Reviews.