We went on with connecting up what we could think of and discover about immigration into islands and extinction of species, connecting it up, what was known with ecology, which was then emerging into a new phase based upon demography, the life and death of organisms. So here we were, for the first time, able to start at the level of individual organisms and individual species — living, reproducing, dying at a certain rate, interacting with one another as species that aggregate, and then dispersing — as a result of having actually produced models that were predictive about what the outcome would be, in terms of diversity on islands. It was crude. It was very crude, and it’s been largely replaced by more sophisticated models, but that, in essence, was the theory of island biogeography.