Just because there are strengths associated with diagnostic criteria doesn’t mean it’s a product of evolution. There’s a huge crossover between PTSD and ADHD. And, anxiety over a tiger killing your kids when there are tigers around who will kill your kids isn’t anxiety, that’s fear. Clinical anxiety is the feeling of impending doom with no clear causation. In the debate of nature v. nurture I’m a nurture guy with the understanding that nature plays a huge part.