The transition to modernity and chronic disease: mismatch and natural selection

The Industrial Revolution and the accompanying nutritional, epidemiological and demographic transitions have profoundly changed human ecology and biology, leading to major shifts in life history traits, which include age and size at maturity, age-specific fertility and lifespan. Mismatch between past adaptations and the current environment means that gene variants linked to higher fitness in the past may now, through antagonistic pleiotropic effects, predispose post-transition populations to non-communicable diseases, such as Alzheimer disease, cancer and coronary artery disease. Increasing evidence suggests that the transition to modernity has also altered the direction and intensity of natural selection acting on many traits, with important implications for public and global health. The authors review the changes in life history traits brought forth by the Industrial Revolution and the evidence for antagonistic pleiotropic effects, whereby genetic variants associated with higher fitness in the past now predispose to diseases such as cancer and coronary artery disease.