From the material now at our disposal certain general conclusions can be drawn.
A comparison of the physical measurements indicates that no group is of pure race. There are significant variations between members of different tribes, but these occur also between individuals of the same village. The average person in each group is short-headed, yet long-headed individuals are found in every tribe and variations just as great as this appear in the other measurements and observations.
We have previously noted the evidences of an aboriginal pygmy population, that has been partially absorbed by intermarriage with the later comers.[140] In all the groups, except the Bila-an, the percentage of individuals showing evidences of Negrito blood increases as we go from the coasts toward the interior, until in such divisions as the Obo and Tigdapaya of the Bagobo, and the Tugauanum of the Ata, practically all the people show traces of this admixture.
[140] Negrito are reported from the Samal Islands in the Gulf of Davao.
In addition to the types already described there are found in each tribe individuals who in all but color might readily pass as white men. These persons freely intermarry with the rest of the population, and it is no uncommon thing to find in one family children of this sort as well as those showing Negrito characteristics or those conforming to the average type.[141]
[141] This will be discussed in a forthcoming publication on Physical Types. That paper will present a full series of measurements accompanied by photographs, including the Bukidnon of North Central Mindanao in which tribe this type is more frequently seen than in Davao District.
The facts indicate that the tribes now found in Davao District did not reach the coasts of Mindanao at the same time, but rather that they represent several periods of migration, of which the Kulaman is the last. This tribe, which only a few generations ago seems to have been made up of seafarers, has not yet entirely adapted itself to a settled existence and it is only within the lifetime of the present generation that its members have taken seriously to agriculture.
It appears that the Bila-an once inhabited the district about Lake Buluan, but the pressure of the Moro has forced most of them from that region toward the mountains to the south and east. They have taken possession of both sides of this mountain range, except for the lower eastern slopes where they have encountered the Tagakaolo.
The other tribes probably landed on the southern or southeastern coast of the Island, from whence they have gradually moved to their present habitats.
Intermarriage between the tribes, Moro raids, warfare with the accompanying capture of slaves, and the possible influence of boat-loads of castaways, all have to be considered in dealing with the types found in Davao District. We have already seen that the physical measurements indicate a complex racial history.