Too harsh the environmental conditions accelerate the process of evolution. But the faster flows the evolution of a species, the higher the likelihood of deviations and mutations.
Does it work with our character, according to your theory? A more difficult life situations cause more thoughts. More thoughts, the stronger the struggle, the evolution of character is going faster. As a result- the occurrence of abnormalities in the form of psychological injuries, deviations and shortcomings in behaviour/character.
difficulties do not cause more thoughts but more "rigorous selection", since fewer options are generally available during difficult times. When your hand is in a meat grinder it would be a lot less likely that one would be daydreaming of a day at the beach.