Emigration from islands readily throws itself into the channel of navigation and foreign trade.  The northern Sporades, especially Skiathos and Skopelos, are the home of sailors who can be found over all the world.[994] In this appetency for a nautical career, small inshore islets are often distinguished from the nearby mainland.  Nearly all the masculine population of the Frisian Islands were seamen prior to 1807.  In the eighteenth century a third of the Hamburg vessels were commanded by captains from the little island of Sylte, and a third of the Greenland fleet of the Netherlands by natives of Foehr.[995]

In England the exodus took the form of trading expeditions and the foundation of commercial colonies long before the food resources of the island had been even considerably developed.  The accessible sea offered lines of least resistance, while the monopoly of the land by a privileged aristocracy and the fiercely defended corn laws made the limitations of a small area more oppressive.  In Ireland, a landless peasantry in a grainless land, dulled by deprivation of opportunity, found in emigration an escape from insupportable evils.

[Sidenote:  Artificial checks to population.]

While emigration draws off the surplus population, there tend to develop in islands, as also in barren highlands where population early reaches the point of saturation, various devices to restrict natural increase.  The evils of congestion are foreseen and guarded against.  Abbe Raynal, writing of islanders in general, remarked as far back as 1795, “It is among these people that we trace the origin of that multitude of singular institutions which retards the progress of population.  Anthropophagy, the castration of males, the infibulation of females, late marriages, the consecration of virginity, the approbation of celibacy, the punishments exercised against girls who become mothers at too early an age,” he enumerates as such checks.  Malthus, in his Essay on Population, commenting on this statement, notes that the bounds to the number of inhabitants on islands, especially small ones, are so narrow and so obvious that no one can ignore them.[996]

The checks to population practiced on islands are either preventive or positive.  The extreme measure to restrict marriage is found among the wretched Budumas who inhabit the small, marshy islands of Lake Chad.  Tribal custom allows only the chiefs and headmen to have wives.  A brass crescent inserted in the ear of a boy indicates the favored one among a chief’s sons destined to carry on his race.  For his brothers this is made physically impossible; they become big, dull, timid creatures contributing by their fishing to the support of the thinly populated villages.  The natives of the Shari River delta on the southern shore of Lake Chad use Buduma as a term of contempt for a man.[997]

[Sidenote:  Polyandry.]