An excerpt from Livescience.com discussing our ability to make decisions and worrying:
Recent research by Louisa Egan, Laurie Santos and Paul Bloom at Yale University demonstrated with capuchin monkeys and 4-year-old kids that the ability to self-deceive is deeply engrained in us primates. Capuchins will choose one color M&M over another (and let’s face it, all M&M’s taste the same) and then downgrade the other color, and little kids will do the same with stickers.
Our brains, then, weren’t so much designed to make choices as to pretend, no matter what, that we made the right choices. The goal seems to be mental peace; as we all know too well, the time from bad choice to righteousness is very uncomfortable and so the sooner we justify our decisions, the better.
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Worrying about something as silly as the choice of a new pair of shoes distracts a person from the truly important choices in life, such as how to find a mate and pass on genes.
Also, the worried brain is a useless organ. When the time comes to make evolutionarily significant decisions, such as jumping out of the way of a car and making sure your genes aren’t eliminated form the gene pool, it’s a good idea to have a clear head. One doesn’t want anxiety about the choice of paper vs. plastic to get in the way of feeding the baby, that packet of one’s genes.