For 99.9 percent of the time since our species came to be, we were hunters and foragers, wanderers on the savannahs and the steppes. There were no border guards then, no custom officials. The frontier was everywhere. We were bounded only by the Earth and the ocean and the sky — plus occasional grumpy neighbors.
When the climate was congenial, though, when the food was plentiful, we were willing to stay put. Unadventurous. Overweight. Careless. In the last 10,000 years — an instant in our long history — we’ve abandoned the nomadic life. We’ve domesticated plants and animals. Why chase the food when you can make it come to you?
For all its material advantages, the sedentary life has left us edgy, unfulfilled. Even after 400 generations in villages and cities, we haven’t forgotten. The open road still softly calls, like a nearly forgotten song of childhood.
– Carl Sagan in Pale Blue Dot