Modern Selection Pressures

Medicine changes which pressures matter, not whether evolution happens. Caesarean sections now let babies with larger heads be born safely, which may be relaxing a constraint that once limited head size — though how much this actually shifts the population is still debated.

Not every modern change is natural selection, though. Myopia has roughly tripled in East Asia over the past 50 years, but the cause is mostly environmental — far less time outdoors and intense close-up work — a reminder that the world we build can reshape a trait without rewriting our genes.

We are still adapting, just under different pressures than those our ancestors faced on the African savannah. What changes now is the pace and direction, set by the world we have built rather than the one we left behind.