Early settlers self-selected for risk-taking and resourcefulness merely by being willing to say goodbye to all they knew and get on a boat for a dangerous months long journey to a wild and unsettled place. Then there’s hybrid vigor once they were established here and began intermarrying with other settlers from other places.
and they were good at problem solving.
Which they don’t teach anymore.
Let’s hear it for heterosis, and I don’t mean halitosis. ;-) See below for technical details.
http://www.pnas.org/content/103/35/12957.full