Wasn’t child mortality only super high in dense population settings relatively recently? Like if you are a tribe in the middle of nowhere in Northern Europe 20k

Wasn’t child mortality only super high in dense population settings relatively recently? Like if you are a tribe in the middle of nowhere in Northern Europe 20k years ago, for example, you are probably not exposed to much contagious disease. Disease is a network phenomenon, and prior to modern medicine humans had increased network speeds and connectivity massively, but that wasn’t the historical norm, was it?