Homo sapiens, industrialisation and the environmental mismatch hypothesis.

For the vast majority of the evolutionary history of Homo sapiens, a range of natural environments defined the parameters within which selection shaped human biology. Although human-induced alterations to the terrestrial biosphere have been evident for over 10,000 years, the pace and scale of change has accelerated dramatically since the onset of the Industrial Revolution in the late 18th century. Industrialisation has profoundly transformed our various natural habitats, driving rapid urban expansion, increasing reliance on fossil fuel energy and causing environmental contamination, ecosystem degradation and biodiversity loss. Today, most of the world's population resides in highly industrialised urban areas. These new primary human habitats differ fundamentally from our ancestral natural habitats, creating novel environmental challenges while, simultaneously, lacking key natural features linked to health and function. Although the adaptive capacity of humans has enabled survival in diverse and fluctuating environmental conditions, this capacity is limited. It is possible that the rapid industrialisation of our habitat is outpacing our adaptive capacity and is imposing selective pressures that threaten our evolutionary fitness. A growing body of observational and experimental evidence suggests that industrialisation negatively impacts key biological functions essential for survival and reproduction and, therefore, evolutionary fitness. Specifically, environmental contamination arising directly from industrial activities (e.g. air, noise and light pollution, microplastic accumulation) is linked to impaired reproductive, immune, cognitive and physical function. Chronic activation of the stress response systems, which further impairs these biological functions, also appears more pronounced in industrialised areas. Here, we consider whether the rapid and extensive environmental shifts of the Anthropocene have compromised the fitness of Homo sapiens. We begin by contrasting contemporary and ancestral human habitats before assessing the effects of these changes on core biological functions that underpin evolutionary fitness. We then ask whether industrialisation has created a mismatch between our primarily nature-adapted biology and the novel challenges imposed by contemporary industrialised environments - a possibility that we frame through the lens of the Environmental Mismatch Hypothesis. Finally, we explore experimental approaches to test this hypothesis and discuss the broader implications of such a mismatch.