Environmental conditions are a big factor as well. We've existed as humans for ~300k years, but it was only ~10k years ago that we learned agriculture and civil

Environmental conditions are a big factor as well. We've existed as humans for ~300k years, but it was only ~10k years ago that we learned agriculture and civilization-building. That coincided with the beginning of the Holocene Epoch, when the world got warmer, the glaciers melted, and the sea level rose by 400 feet. We must have had those capabilities all along, but it was only when the conditions were right that they were able to be fully expressed.