Your body and genetics, it takes a really long time to evolve a different body (thousands of generations), but it takes very little time to update culture (couple of generations).
There is evidence that single generation evolution can happen with strong enough shocks. Nothing immediately obvious, just detectable DNA changes that lead to changes in risk for certain conditions.
https://amp.theguardian.com/science/2015/aug/21/study-of-hol...
https://en.m.wikipedia.org/wiki/%C3%96verkalix_study