The same policy of monopoly and exclusion has been pursued by the Moro coast dwellers of Mindanao in relation to the pagan tribes of the interior.  They buy at low prices the forest and agriculture products of the inland Malays, whom they do not permit to approach either rivers or seaboard, for fear they may come into contact with the Chinese merchants along the coast.  So fiercely is their monopoly guarded by this middleman race, that the American Government in the Philippines will be able to break it only by military interference.[512]

[Sidenote:  Differentiation of coast from inland people.]

Differences of occupation, of food supply, and of climate often further operate to differentiate the coast from the inland people near by, and to emphasize the ethnic difference which is almost invariably present, either inconspicuously from a slight infusion of alien blood, or plainly as in an immigrant race.  Sometimes the contrast is in physique.  In Finisterre province of western Brittany, the people along the more fertile coastal strip are on the average an inch taller than the inhabitants of the barren, granitic interior.  Their more generous food supply, further enriched by the abundant fisheries at their doors, would account for this increased stature; but this must also be attributed in part to intermixture of the local Celts with a tall Teutonic stock which brushed along these shores, but did not penetrate into the unattractive interior.[513] So the negroes of the Guinea Coast, though not immune from fevers, are better nourished on the alluvial lowlands near the abundant fish of the lagoons, and hence are often stronger and better looking than the plateau interior tribes near by.  But here, again, an advantageous blending of races can not be excluded as a contributing cause.[514] Sometimes the advantage in physique falls to the inland people, especially in tropical countries when a highland interior is contrasted with a low coast belt.  The wild Igorotes, inhabiting the mountainous interior of northern Luzon, enjoy a cooler climate than the lowlands, and this has resulted in developing in them a decidedly better physique and more industrious habits than are found in the civilized people of the coasts encircling them.[515]

[Sidenote:  Early civilization of coasts.]

Where a coast people is an immigrant stock from some remote oversea point, it brings to its new home a surplus of energy which was perhaps the basis of selection in the exodus from the mother country.  Such a people is therefore characterized by greater initiative, enterprise, and endurance than the sedentary population which it left behind or that to which it comes; and these qualities are often further stimulated by the transfer to a new environment rich in opportunities.  Sea-born in their origin, sea-borne in their migration, they cling to the zone of littoral, because here they find the conditions which they best know how to exploit.