In November 1963 an island rose out of the sea south of Iceland, and the scientists who named it Surtsey decided almost at once to keep everyone else off, so they could watch life arrive on bare rock with nobody helping. The first plant came by sea in 1965, a sea rocket washed up on the shore, and after that seeds rode in on waves, wind and birds. A few years in, the researchers found a tomato seedling growing in the warm ground. Nobody had planted it. Someone on the team had needed the toilet, and the tomato came from their lunch. They pulled it up. Of all the ways a seed could reach that island, it took the one the whole arrangement was built to rule out: it came in with the people keeping watch.