Trying to understand early human migration
Hi all!
So so eons ago humans were inhabiting Africa. Then something (overpopulation, diminishing resurces, other) pushed some of them outside the continent. Not all survived the trip (the famous bottleneck), but once established on the new pastures, they started to multiply and spread, bringing us to the modern 8+ billions. Now comes my question. In the modern era there is still enough pastures for everyone (some may argue, but still), and in the age of world spreading the population was much-much-much smaller. So seeking the fertile lands across rivers is understandable. But what kept pushing humans to populate the hostile unforgiving environments like deserts or tundra or high frost mountains, or to traverse wide spaces to establish on some remote land masses?
It's fascinating how this something pushed humans from Africa all across the eurasian continent up to Australia or high in the Andes. But what and why?
As I said the resources should have been somewhat abundant compared to the population size at the time, so it should be something extra, some factor stimulating the explore itch.