There are a lot of highly repetitive tasks in a hunter and gatherer lifestyle (e.g. gathering, making tools and clothes, tracking, plus all of the memorizing th

There are a lot of highly repetitive tasks in a hunter and gatherer lifestyle (e.g. gathering, making tools and clothes, tracking, plus all of the memorizing that comes with a non-written cultural tradition). I'm sure someone with a deep special interest in horse behavior would have been extremely useful for groups that subsist on the wild horses of the European tundra. Same for people with ADHD, someone who is highly motivated by novelty and prone to risk-taking should be pretty useful for finding new hunting and gathering opportunities and adapting to changing environments. You won't find out there are plump tasty BBQ birds on that island in the distance if you don't brave the journey.