Two problems may be distinguished here which have too often been confounded in discussions of the mental characteristics of civilized man and of primitive man. The one relates to the distinctions between races; the other, to distinctions between the social strata of the same race. According to the meaning of the terms “civilized” and “primitive,” it is perfectly conceivable that there may be civilized groups belonging to different races (like the Chinese and Europeans), and civilized as well as primitive groups, both belonging to the same race (like the Yukaghir of Siberia and the Chinese, or like the group of educated negroes in the United States and the primitive tribes of the coasts of Africa). The problems presented by the differences between the various races of man, and by the differences between social groups in the same races, are, of course, entirely distinct, and each requires separate treatment.

There is one peculiarity common to both problems, which must be described before we can properly take up their treatment. When we compare the individuals comprising any one racial or social type, we find that they are not by any means uniform, but exhibit considerable variation. When we try to think of a Norwegian and of a negro, two entirely distinct types will be present to our minds,—the Norwegian, tall, with blond and somewhat wavy hair, blue eyes, light complexion, delicate face and nose; the negro, of medium stature, with black and frizzly hair, dark eyes, dark skin, projecting jaw, and heavy flat nose. Still, these pictures are only abstractions of what we think we have noticed most commonly in each type. When we compare the Norwegians among themselves, or the negroes among themselves, we find that each individual in each series has his peculiarities, which the others do not share. There are tall and short Norwegians; their hair is blond or dark, straight or wavy; their eyes vary from brown to blue; their complexion is light or dark, their faces more or less delicate. And so with the negroes. The degree of blackness, the amount of projection of the chin, the flatness of the nose,—all show very considerable variations. Experience has demonstrated that in all cases of this kind, one certain type, one certain combination of features, is most common; and that deviations in either direction from this type become the rarer, the greater their amount. Thus the Norwegians show a prevalence of a certain blond color. Individuals with a color of hair much lighter than the most common color are the rarer, the greater the difference of their hair-color from the most common one; and in the same way individuals with a color of hair much darker than the most common color are the rarer, the greater the deviation of their color of hair from the common one. The extent to which such variations occur is not always the same. In some cases the individuals constituting the group show a remarkable similarity or uniformity of type; in other cases the diversity of types occurring in the same community is quite remarkable. We call a series the more variable, the more frequently deviating types occur in it; so that the average amount of differences between the individuals constituting the series and the most common type may be used as a measure of the variability of the series.

These considerations are of prime importance in all attempts to compare different races. In some cases differences are found which are sufficiently fundamental to distinguish easily and definitely one from another. Thus the color of the skin, color and form of the hair, and configuration of lips and nose, distinguish the African negro definitely from the North European. When, however, we compare all the races and types of man, we find that innumerable transitions exist, which would make it difficult to state that any one particular feature belongs to all the individuals of one type, to the exclusion of all others. Thus it would not be difficult to find among members of the American race, for instance, lips and nose which approach in form those of the negro. The same may be said of color. This indefiniteness of distinctions between different types is due to the variability of the types, which has been described before, and to the comparatively small differences between the types.

To give an instance. Negroes have thick lips. Nevertheless the thickness is not the same among all of them. In some cases it is quite small, in others very large. Europeans have thin lips, but we can find individuals whose lips have very considerable thickness. Thus it happens that there are some negroes whose lips deviate from the normal type in being unusually thin, and whose lips are therefore similar to those of Europeans whose lips are unusually thick. The less distinct two types are, the greater will be the number of individuals in both groups that are alike. It follows also, from what has been said, that the greater the variability of each type, the greater will be the probability that some individuals of the two types compared will be alike. We may perhaps best express this by saying that the varieties constituting each race overlap. In many cases, and in some of those that are most important for our inquiry, this overlapping is extended. Thus I have pointed out the differences in average brain-weight between different races. Brain-weights are, however, so variable, that a considerable overlapping occurs, and that even the average sizes of the brains of the white race are numerously represented among other races. Medium-sized brains of whites may be represented by the group of individuals having skull capacities of from 1450 cc. to 1650 cc. This group embraces 55 per cent of the Europeans, 58 per cent of the African negroes, and 58 per cent of the Melanesians. The same result appears when we compare the number of individuals having great cranial capacities. We find that 50 per cent of all whites have a capacity of the skull greater than 1550 cc., while 27 per cent of the negroes and 32 per cent of the Melanesians have capacities above this value. If we were to assume a direct relation between size of brain and ability,—which, as we have seen before, is not admissible,—we might, at most, anticipate a lack of men of high genius, but should not expect any great lack of faculty among the great mass of negroes living among the whites, and enjoying the advantages of the leadership of the best men of that race.

On the other hand, we find characteristics in different races so far apart and so little variable, that an overlapping is entirely or practically excluded. Examples of these are the frizzly hair of the negro as compared with the straight hair of the Mongol; the elevation and narrowness of the nose of the Armenian, and the flatness of the negro nose; the differences in pigmentation of the North European and of the Central African.

Investigations on the character of variability, which have been based on the measurements of the body, on social and economic phenomena, and also on variable physical phenomena, such as meteorological data, have resulted in the discovery that almost always the same law nearly covers the distribution of the numerical values of the observations (Lock, Bowley).

Fig. 1.

It has been shown that the values which represent the phenomenon are so distributed that certain numerical values occur very frequently, and that the greater the difference between an observation and the value at which the greatest number of cases are found, the less will be the number of these observations. The character of this distribution is shown in [Fig. 1], in which the horizontal line represents the numerical values of the observations, while the vertical distances represent the frequency of that observation to which the vertical distance belongs. In the theoretical distribution which is represented in [Fig. 1], the following values of the stature of a number of men are found:—

1415-1455 mm.5 cases
1455-1495 mm.11 cases
1495-1535 mm.44 cases
1535-1575 mm.135 cases
1575-1615 mm.325 cases
1615-1655 mm.607 cases
1655-1695 mm.882 cases
1695-1735 mm.1000 cases
1735-1775 mm.882 cases
1775-1815 mm.607 cases
1815-1855 mm.325 cases
1855-1895 mm.135 cases
1895-1935 mm.44 cases
1935-1975 mm.11 cases
1975-2015 mm.5 cases