[mikhailfranco]

It's an inevitable result of Darwinian evolution: the rate of change is greatest where the competitive or environmental pressure is highest.

http://en.wikipedia.org/wiki/The_Third_Man#.22Swiss_cuckoo_c...

For example, you don't go from Kitty Hawk to the moon in 67 years without two World Wars and a Cold War.

[nieve]

Or perhaps we're seldom willing that level of resources without great pressures. Even the much lower current US expenditures on research have been shown to be hugely rewarding economically we've kept cutting them. Pressure inducing behavior changes isn't quite the same as evolution, it happens on a much shorter time scale and isn't likely to follow the same curves when you remove the stimulus.