Humans evolved worrying alongside intelligence - perhaps as a defense mechanism in a dangerous world where early humans had to fight for survival

While excessive worry is generally seen as a negative trait and high intelligence as a positive one, worry may cause our species to avoid dangerous situations, regardless of how remote a possibility they may be. In essence, worry may make people take no chances, and such people may have higher survival rates. Thus, like intelligence, worry may confer a benefit upon the species. High intelligence and worry both deplete the same nutrient in the brain's white matter - suggesting they evolved at the same time. Worry might actually be a useful trait that helped our species to survive. Humans are the most intelligent species and also appear to suffer disproportionately from psychopathology.