The mind of primitive man

by Franz Boas

The results of our inquiry have led to the unexpected result that the American-born descendants of these types differ from their parents; and that these differences develop in early childhood, and persist throughout life. It is furthermore remarkable that each type changes in a peculiar way. The head of the American-born Sicilian becomes rounder than that of the foreign-born. This is due to a loss in length and an increase in width. The face becomes narrower, the stature and weight decrease. The head of the American-born Central European loses both in length and width, more so in width, and thus becomes more elongated. The face decreases very much in width; stature and weight increase. The modifications of the American-born descendants of the Scotch type are not marked, except that stature and weight increase. The American-born Hebrew has a longer and narrower head than the European-born; the head is therefore considerably more elongated. His face is narrower; stature and weight are increased. In none of the types have marked differences in color of hair between American-born and foreign-born been found.

In order to understand the causes which bring about these alterations of type, it is necessary to know how long a time must have elapsed since the immigration of the parents before a noticeable change of type of the offspring is brought about. This investigation has been carried out mainly for the cephalic index, which, during the period of growth of the individual, undergoes only slight modifications. The investigation of the Hebrews shows very clearly that the cephalic index of the foreign-born is practically the same, no matter how old the individual at the time of immigration. This might be expected when the immigrants are adult or nearly mature; but it is of interest to note that even children who come here when one year or a few years old develop the cephalic index characteristic of the foreign-born. This index ranges around 83. When we compare the value of this index with that of the index of the American-born, according to the time elapsed since their immigration, we find a sudden change. The value drops to about 82 for those born immediately after the immigration of their parents, and drops to 79 in the second generation; i.e., among the children of American-born children of immigrants. In other words, the effect of American environment makes itself felt immediately, and increases slowly with the increase of time elapsed between the immigration of the parents and the birth of the child.

The conditions among the Sicilians and Neapolitans are quite similar to those observed among the Hebrews. The cephalic index of the foreign-born remains throughout on almost the same level. Those born in America immediately after the arrival of their parents show an increase of the cephalic index. In this case, the transition, although rapid, is not quite so sudden as among the Hebrews, probably because among those born a year before or after immigration there is some doubt as to the place of their birth. These uncertainties are due to the habit of the Italians to migrate back and forth between Italy and America before finally settling here, and to the indefiniteness of their answers in regard to the places of birth of the child, which sometimes had to be inferred from the age of the child and the year of immigration of the mother. As long as this uncertainty exists, which is hardly present at all in the data relating to the Hebrews, it does not seem necessary to assume any other cause for the more gradual change of the cephalic index about the time of immigration.

The Italian immigration is so recent, that individuals who were born many years after the arrival of their parents in America are very few in number, and no individuals of the second generation have been observed. For this reason it is hardly possible to decide whether the increase of the cephalic index continues with the length of time elapsed between the immigration of the parents and the birth of the child.

The explanation of these remarkable phenomena is not easy. Whatever their causes may be, the change in form cannot be doubted. It might, however, be claimed that the changes are not due to deep physiological causes, but to the changes of certain external factors. The composition of the immigrant population might be such that the people who came here at different periods had distinct physical characteristics, and that these are now reflected in the descendants of the older generations when compared with the more recent immigrants. It can be shown, however, that the differences between the Hebrews who immigrated at different periods between 1860 and 1909 are so slight that they cannot account for the type of the descendants of immigrants. This important point can be elucidated more definitely by the application of a different method. For this purpose I have compared the cephalic index of all immigrants of a certain year with that of their descendants. It appears from these comparisons that the differences which are exhibited by the whole series exist also between the immigrants who arrived here in a certain year and their descendants. This purely statistical explanation of the phenomenon may therefore be dismissed.

More difficult to investigate is the hypothesis that the mechanical treatment of infants may have a decided influence upon the form of the head, and that the changes in cradling and bedding which are made by some immigrants almost immediately after their arrival in America account for the changes of head-form. If this were true, the continued changes among the Hebrews might indicate merely that the American method of cradling is used the more frequently, the longer the family has resided in this country. A number of investigators have claimed that the position of the child on the back tends to produce short-headedness, and that the position on the side tends to produce long-headedness (Walcher). There is good evidence that a flattening of the occiput occurs when a very hard pillow is used and the child lies permanently on its back. This is the case, for instance, among many Indian tribes, and similar results might obtain if a swathed child were to lie permanently on its back. The prevalence of rachitis in New York would favor distortion due to pressure.

While I cannot disprove the existence of such influences, I think weighty considerations are against their acceptance. If we assume that among the Hebrews the children born abroad have a lesser length of head than those born here because they are swathed and lie more permanently on their backs than the American-born children, who can move about freely, we must conclude that there is a certain compensatory decrease in the other diameters of the head of the American-born. Since this compensation is distributed in all directions, its amount in any one direction will be very small (Boas).

The decrease in the width of head that has been observed is so large that it cannot be considered simply as an effect of compensation; but we have to make the additional hypothesis that the American-born children lie so much on their sides that a narrowing of the head is brought about by mechanical pressure. The same considerations hold good in all the other types. If, therefore, in one case the greater freedom of position of the child increases the length of its head, it is difficult to see why, among the Bohemians, the same causes should decrease both horizontal diameters of the head, and why, among the Sicilians, the length should decrease, the width increase.

The development of the width of the face seems to my mind to show most clearly that it is not the mechanical treatment of the infant that brings about the changes in question. The cephalic index suffers a very slight decrease from the second year to adult life. It is therefore evident that children who arrive in America very young cannot be much affected by American environment in regard to their cephalic index. On the other hand, if we consider a measurement that increases appreciably during the period of growth, we may expect that in children born abroad but removed to America when young, the total growth may be modified by American environment. The best material for this study is presented by the Bohemians, among whom there are relatively many full-grown American-born individuals. The width of face of Bohemians, when arranged according to their ages at the time of immigration, shows that there is a loss among those who came here as young children,—the greater, the younger they were. Continuing this comparison with the Americans born one, two, and more years after the arrival of their mothers, the width of face is seen to decrease still further. It appears, therefore, that the American environment causes a retardation of the growth of the width of face at a period when mechanical influences are no longer possible.

I have not carried through the analogous investigation for stature, because in this case the increase might simply be ascribed to the better nutrition of most of the north and central European immigrants after their immigration into this country.