The feature of the epicanthic fold, particularly prevalent among East Asian populations descended from Haplogroup A, is an adaptation to cold, windy, and bright environments encountered as humans migrated northward from Africa. This phenotype likely developed to protect the eyes from frostbite and snow blindness, showcasing how genetic diversity within human lineages adapted to specific environmental challenges.
In the shadowed forests of the Late Carboniferous, long before mammals, birds, or even dinosaurs,
