The human brain evolved for a world of familiar faces, immediate threats and small social groups. But the world around us is changing far faster than human biology can keep pace. That mismatch may help explain some of the stress, loneliness and constant comparison people experience today.

The review, co-authored by Dr. Jose Yong, senior lecturer at James Cook University, Singapore, and Dr. Sarah Chan, research fellow at the Lee Kuan Yew Centre for Innovative Cities at SUTD, is published in Behavioral Sciences. Titled Evolutionary mismatch, stress, and competition: Making sense of psychosocial problems in the polycrisis era, it examines how stress, competition and loneliness can be understood through an evolutionary lens.

Evolutionary mismatch describes what happens when human instincts shaped in one kind of environment are forced to operate in a very different one. Humans evolved in smaller, close-knit groups, where danger, belonging, status and trust were read through familiar people and everyday face-to-face signals. Now, those same instincts are being triggered in dense cities, digital platforms, unequal societies and a world shaped by overlapping pressures. The result is internal confusion: Responses that once made sense in a small, familiar group can feel out of place, or simply overwhelming, in modern life.

Social media makes this mismatch especially visible. The urge to understand our place within a group may once have helped people maintain trust and cooperation among familiar faces. Today, that same instinct can be triggered by an endless stream of curated lives, achievements and status signals.

At the center of the paper is competition. Modern environments can intensify the feeling that others are judging, outperforming or leaving us behind. The authors propose that this heightened sense of competition may be one pathway through which evolutionary mismatch contributes to stress and poorer well-being.

"Competition is not new, but modern life can make it feel constant," said Yong. "An evolutionary perspective may help explain why people respond so strongly to comparison and the fear of falling behind, even when those signals come from strangers or screens rather than a small social group."

The paper draws on existing research and theory rather than new data. It presents evolutionary mismatch as one way of understanding modern social and psychological problems, alongside psychological, social and economic explanations. These ideas will need to be tested through real-world research.

That matters because the response to modern stress cannot rest only on telling individuals to be more resilient. If environments are activating old instincts in new and unhelpful ways, then cities, workplaces, digital platforms and communities also need to be part of the solution.