The living world in which we humans are a part of was shaped over billions of years of evolution. Over time, different organisms have adapted genetically via natural selection to different environments: Polar bears are designed to live in cold, arctic habits and eat a meat-heavy diet; cows function best when they have access to green, open pastures covered in grass; tigers are morphologically sculpted to eat primarily meat and live in hot, sunny environments; and so forth.
The environments in which organisms live are not static; hence, one shouldn’t necessarily expect organisms to become “perfectly matched” to their environment. With that said, all organisms have a niche in which they are best adapted to live. For some organisms, this niche is narrow, whereas for others, it’s quite broad.
If a group of organisms abandon the environment(s) they are evolutionarily adapted for or the environment(s) in which they live change rapidly and/or profoundly, mismatches between genes and environmental conditions result. These mismatches can manifest themselves in a variety of ways. Organisms that are subjected to environments that differ markedly from the environments in which they evolved to live express a suboptimal phenotype and suffer health wise. Their Darwinian fitness may also be affected.
Why it’s important to know about evolutionary mismatch theory
The evolutionary mismatch concept is particularly relevant in the times in which we live, seeing as the environment of the Earth has changed dramatically over the most recent millennia, in large part because of human activities. As a result, many organisms, including most humans, today live in an environment that is mismatched with their biology. A large body of research shows that evolutionary mismatches underlie a staggering number of diseases and health problems (1, 2, 3, 4, 5).
The infographics below depict the relationship between environmental change, evolutionary mismatches, and the health of contemporary humans.
The etiology, prevention, and treatment of the diseases of civilization: A Darwinian conceptual framework
The Human Condition: From Hunter-Gatherer to Doughnut-Eating Office Worker
10 Diseases Caused by Evolutionary Mismatches