Humans may feel at home in cities, but our bodies tell another story.
According to a new study by evolutionary anthropologists Colin Shaw from the University of Zurich and Daniel Longman from Loughborough University, modern life has moved far faster than human evolution.
Their research argues that many of today’s health problems and rising stress levels are caused by a serious “mismatch” between the kind of environment humans evolved for and the kind we now live in.
The paper was published in the journal Biological Reviews.
For hundreds of thousands of years, human beings lived as hunter-gatherers.
Life was physically demanding, but it took place in natural surroundings filled with trees, open land, fresh air, changing sunlight, and seasonal rhythms.
Stress existed, but it came in short bursts. A wild animal might appear, creating fear and adrenaline, but once the danger passed, the body could relax again and return to balance.
Modern life is very different.
Over the past few centuries, humans have built industrialised societies filled with noise, constant light, pollution, chemicals, processed food, plastic, traffic, screens, and long hours of sitting.
These changes happened extremely fast in evolutionary terms. While our surroundings changed quickly, our biology stayed much the same.
The problem is that our bodies still respond to stress in a very ancient way. When a person hears loud traffic, faces pressure at work, or feels overwhelmed by social media, the body reacts as if it is facing a dangerous animal.
Stress hormones are released and the nervous system becomes highly alert. The trouble is that, unlike a lion that eventually goes away, modern stress never really ends. There is no real recovery time. Over months and years, this constant activation can harm the body.
Shaw and Longman reviewed a wide range of studies and found signs that this mismatch is affecting human health and even reproduction. Fertility rates are decreasing around the world, and chronic inflammatory diseases, such as autoimmune conditions, are becoming more common. One striking example is the global decline in sperm count and quality since the 1950s. This trend has been linked to environmental influences like pesticides, chemicals in plastics, and pollution in food and water.
In evolutionary terms, a healthy species is one that can survive and reproduce successfully. While modern society has brought comfort, medicine, and longer lifespans for many people, the researchers argue that some of our biggest achievements may also be quietly damaging our immune systems, brains, bodies, and reproductive health.
Humans cannot simply “evolve” out of this problem, because biological change takes many thousands of years. Instead, the scientists suggest that we need to adapt our environments to suit our biology. This could mean protecting and restoring natural areas, spending more time outdoors, and designing cities that support well-being through clean air, green spaces, quiet zones, and more natural light.
By understanding how different parts of the environment affect things like heart rate, blood pressure, and the immune system, researchers can help guide better choices in city planning and public health.
In the end, the message is simple: to stay healthy in the modern world, humans may need to reconnect with the natural one they were built for.
