Gene variants that influence human biology today reflect thousands of years of evolution. Genetic effects on infant health are a major point of selective pressure, given that childhood survival is essential to evolutionary success. Knowledge of this evolutionary history can have implications for paediatric research. CONCLUSION: An episode of human adaptation to the extremely low ultraviolet radiation environment of the Arctic 20,000 years ago implicates the Ectodysplasin A Receptor (EDAR) and the Fatty Acid Desaturases (FADS) in human lactation and epithelial inflammation.