Sure, but so does positivity. Those who found pleasure in certain things also survived to produce children. It's not like the human brain values negativity over positivity. Negativity just gets more psychological press.

It's more direct and immediate and outcomes are more discernable and more easily categorized in a bimodal way.

But that's reductive. We don't just live and survive in big moments. There's all the little day to day that always gets overlooked and left inconsiderate that determines whether we survive to reproduce.

Plus, the "evolution made us this way" argument ignores the fact that the beliefs we absorb and adopt from abstract thinking drive a lot of our negativity. We create it because of what we choose to believe. That is outside of the evolutionary process.