In hunter gatherer packs, out of 70-100 people, you generally get a loner here and there who pays more attention to the local flora and fauna than to the rest of the tribe, and helps revise the tribe's oral knowledge. You also get the tribe members who feed the orphans instead of siring their own children. It's likely we're evolved to throw dice in our brains so that some of us fill different roles than others, whether it's autistic tendencies or homosexuality.