The ancestors of modern bears were cave bears, and they were larger, stronger, and more resilient, but required more food. The ancestors of modern wolves were dire wolves, and they were larger, stronger, and more resilient, but required more food. The ancestors of modern lions were cave lions, and they were larger, stronger, and more resilient, but required more food. Human ancestors were no exception. I can't speak for the ancestors of all 8.6 billion people, but many of us had ancestors who were larger, stronger, and more resilient, but required more food.
