As explained elsewhere in this volume (Chapter 6) models of migration fall into two general classes: distance models and island models. Human beings are distributed over the surface of the globe in patterns that are neither homogeneous nor completely aggregated. Clustering is observed at every level; in houses, in towns, in cities and conurbations. Although neither type of model exactly fits the human situation, users of both types of model believe that the approximations are good enough to give a true picture of the kinds of differences existing between human populations and of differences in migration rates or distances when compared to those incorporated in the models. For this reason, distance models have sometimes been applied to nucleated as well as evenly distributed populations and island models have been applied to regions of more or less continuous population distribution as well as to regions with discrete non-overlapping demes.

In this chapter I shall describe some properties of island models and apply these models to a group of islands, five of which are at present inhabited, thus comprising five discrete populations separated from each other by water. The findings from the application of such models will then be considered in the light of other studies to which island models have been applied, even though the assumptions of discrete ‘islands’ are imperfectly met.