The “Mamanua” of Surigao peninsula, Mindanao, have long been recognized as of Negrito race. They were seen and described by Montano in 1880. At the present time they are very few in number, and are found in the forest about Lake Mainit and in the hill country southward. They are fast being absorbed by the Manobo, who join their communities and intermarry with them. In a little village called Kicharao in the forest near Lake Mainit are Mamanua men married to Manobo women and Manobo men married to Mamanua women, the children of these unions sometimes presenting Negroid and sometimes Malayan characters. The opportunity to observe the immediate results of mixture between two different races is very unusual. Naturally this group is of mixed race, some individuals looking like pure Negritos and from this type varying all the way to primitive Malayan. Three men whom I measured had a stature exceeding the Negrito but in other respects were Negritic. The statures were 1583, 1594, and 1612; the cephalic indices, 80, 85, and 86; the nasal indices, 97, 102, and 111.
What has not been generally noted, however, is the fact that nearly all the peoples of eastern Mindanao, usually described as “Malayan” or “Indonesian,” are to a large degree Negrito. This is especially true of the Manobo of the lower waters of the river Agusan. I have no measurements of these people, but the appearance of nearly every individual in their communities is Negritic rather than Malayan. The stature is very low and frail, hair black and wavy to frizzly, features negroid, and behavior that of the pacified Negrito. Similar characters, though in a less marked degree, display themselves among the tribes southward and about the gulf of Davao. There is no doubt that there is a large amount of absorbed Negrito stock in the pagan peoples of all this great island. Even among the Subanon of the Samboanga peninsula, who are perhaps as purely Malayan as any, I have seen occasional individuals with marked Negrito characters.
I shall not attempt here to estimate the proportion of Negrito blood in the Christian peoples of the Philippines—Bisaya, Bikol, Tagalog, Ilokano, etc.—further than to express my conviction that in certain regions it is very large and has greatly modified the primitive Malayan type. But let us turn to the consideration of possible Negrito blood in two interesting pagan stocks of northern Luzon, the “Igorot” and the “Ilongot” or “Ibilao.”
The term Igorot is used to include all the wild, headhunting, mountain-dwelling peoples of the great cordillera of Luzon, a region some two hundred miles in length by forty across. This mountain area is divisible into regions wherein the culture, physical type, and language of the inhabitants are homogeneous or nearly so. These regions, in reports made some years ago on the wild tribes of the Philippines, I have called “culture areas,” and they may serve, in the absence of the tribal relation, as the basis of classification. Beginning with the southern end of this mountain system we have the area of southern Benguet and Kayapa inhabited by Igorot speaking a dialect called “Nabaloi.” In northern Benguet, Amburayan, and southern Lepanto are the “Kankanay.” In the central mountain region, a great area with several subdivisions, the “Bontok”; and southeast, occupying the former Comandancia of Kiangan, the “Ifugao.” North of Bontok are the “Tinglayan,” the “Tinggian” or “Itnig,” the “Kalinga,” and “Apayao” areas, and perhaps others. Of these most northerly peoples I have no anthropometric data. Their general appearance is somewhat different from that of the Igorot farther south. They appear to the eye to be more slender and handsomely built, with finer features, especially in the case of the Tinggian. I am of opinion, however, that these dissimilarities are apparent rather than real, and that measurements and careful observation will demonstrate unity of physical type throughout the entire cordillera. This unity does not refer of course to manner of dressing the hair, ornamentation, artificial deformations, etc., in which there is wide variation. The ethnological origin of these Igorot peoples is at first very puzzling. They are obviously not typical Malayans. Some physical measurements which I have should, and I believe do, throw some light on the problem.
On September 26, 1902, at Ambuklao, Benguet, I measured ten Igorot men from the villages of Baguio, Trinidad, Tublay, and Ambuklao. All were adults, from 20 to 40 years of age, except one, a boy of 16, who was, however, married and not inferior in stature to the others. These men all belonged to the poor or “kailian” class, except one who had arisen to the “principal” class from poor parentage. By “poor” class in Benguet is meant those who have no cattle, rice terraces, mines, or other productive property and are liable to the forced labor of “polistas.” The stature, arm-reach, and cephalic and nasal indices of these Igorot are arranged below:
| Height | Arm-reach | Cephalic Index | Nasal Index |
| 1481 | 1489 | 83.0 | 82.9 |
| 1490 | 1550 | 75.7 | 85.8 |
| 1496 | 1532 | 78.9 | 104.8 |
| 1499 | 1556 | 79.7 | 83.3 |
| 1500 | 1567 | 76.8 | 83.5 |
| 1512 | 1588 | 87.5 | 75.0 |
| 1522 | 1583 | 76.0 | 89.4 |
| 1546 | 1602 | 81.2 | 97.7 |
| 1596 | 1564 | 82.3 | 79.1 |
| 1615 | 1647 | 96.3 | 105.0 |
Of these statures all but one are “short,” or below 1600. In fact these men are only a little above the average stature of the Negritos of Mariveles (1450). Five are within 50 mm. of a true pygmy stature. The mean stature is 1500 to 1512, and the average is identical, 1505.7. In all but one case the arm reach exceeds the height, the excess varying from 8 to 36 mm. Six are brachycephalic, and four mesaticephalic, the variation extending from 75.7 to 96.3. The nasal index shows wide variation from 75 to 105, the mean being about 85. Four are platyrhinian, two exceeding 100, two are mesorhinian, and four are midway between Topinard’s mesorhinian and platyrhinian types. The muscular development of these men is very strong, robust, or “stocky.” The skin color is coffee brown with saffron undertone, lighter on trunk. Their hair is coarse and in nearly every case straight, in one case only being slightly wavy. The hair is usually scant on the body and about the face, but two men have relatively hairy bodies and legs. The eye in some cases appears to be oblique. The ear in every case is attached and normal. The chin is retreating and in one case the face is somewhat prognathic. The lips are thick and the under lip heavy. In several cases the supraorbital arches are prominent.
On September 29th of the same year, at Wagan, a small town in Kayapa, I measured fifteen Igorot of that town and of Losod. Eight were women and seven were men. The measurements and indices of these follow:
| Stature | Arm-reach | Cephalic Index | Nasal Index |
| Men | |||
| 1413 | 1478 | 78.7 | 125.0 |
| 1493 | 1539 | 80.4 | 86.4 |
| 1512 | 1544 | 82.7 | 84.0 |
| 1550 | 1600 | 78.9 | 90.7 |
| 1589 | 1650 | 73.2 | 90.9 |
| 1594 | 1650 | 78.8 | 100.0 |
| 1653 | 1672 | 74.6 | 140.0 |
| Women | |||
| 1351 | 1376 | 85.1 | 92.6 |
| 1367 | 1394 | 76.7 | 92.7 |
| 1423 | 1467 | 79.1 | 100.0 |
| 1433 | 1466 | 76.8 | 105.7 |
| 1435 | 1455 | 84.8 | 125.3 |
| 1435 | 1522 | 82.6 | 100.0 |
| 1442 | 1446 | 84.6 | 100.0 |
| 1509 | 1520 | 74.4 | 100.0 |
The mean stature (1550) and the average (1526) were a little higher than in Benguet. In every case the arm-reach exceeded the height. The shape of head in men and women shows a wide variation. Seven are brachycephalic and seven are mesaticephalic while one is dolichocephalic (73.2). The nasal index varies from 84 to 140—a truly astonishing series of noses! All are platyrhinian except two, and nine of the sixteen have indices of 100 or over. The descriptive characters were much the same as for the Benguet group. There was occasional marked supraorbital development, retreating chin, and prognathism.