The trouble is if we take no new steps to try a new challenge, our comfort zone doesn't seem just to stay still, but retract.
Two brains are better than one. You've twice the brain capacity and you have two sets of experiences and genes to bring to any challenge.
If we are not using our brains' capacity for challenge it feels to me as though it atrophies like an unused muscle.
When we had to survive on our wits, gather and kill our food from scratch and be more at the mercy of our environment than we are today, we probably had enough challenge to keep our brains healthy.
