From my notes on Coursera’s Positive Psychology course:
The most recent geological epoch that we lived through, the Pleistocene, was the Ice Ages. Famine, flood, ice, drought, more ice.
Now, imagine a primate mentality that thought, “What a lovely day today out there. I bet tomorrow is going to be really lovely as well.” That mentality got crushed by the ice.
The mentality that survived, the brains that we have, are bad weather brains. They’re brains that say “looks like a nice day out there, but tomorrow the ice is coming.”
And that is the way we process, automatically, information about a good world. Depression, anger, paranoia have served us very well. In the Ice Ages, it was a very good idea to think that bad stuff was coming.
But consider the possibility that human progress actually exists, and that prosperity, a good world, living well, not having a tragedy every day is a normal form of life.
If we have the Ice Age mentality, we are incapable of enjoying the prosperity that we have worked so hard to have.
So, if we actually live in a more benign world, and we want to enjoy the world we live in, we have to break the hammerlock of the negative. What needs teaching, what needs nurturance, support and justification is not pessimism, but an optimistic view of the world.