The evolution of group differences in changing environments

TL;DR

This paper explores how complex traits in humans evolve under shifting environmental influences, emphasizing that rapid genetic changes can occur even without changes in optimal trait values, challenging traditional assumptions.

Contribution

It introduces the idea that many complex traits evolve through stabilizing selection amid changing environments, highlighting the importance of environmental effects in interpreting group differences.

Findings

Rapid evolution at trait-associated loci can occur without shifts in trait optima.

Environmental effects significantly influence interpretations of genetic differences.

Stabilizing selection under environmental change complicates assumptions about genetic basis of group differences.

Abstract

The selection pressures that have shaped the evolution of complex traits in humans remain largely unknown, and in some contexts highly contentious, perhaps above all where they concern mean trait differences among groups. To date, the discussion has focused on whether such group differences have any genetic basis, and if so, whether they are without fitness consequences and arose via random genetic drift, or whether they were driven by selection for different trait optima in different environments. Here, we highlight a plausible alternative, that many complex traits evolve under stabilizing selection in the face of shifting environmental effects. Under this scenario, there will be rapid evolution at the loci that contribute to trait variation, even when the trait optimum remains the same. These considerations underscore the strong assumptions about environmental effects that are required in ascribing trait differences among groups to genetic differences.