[35] Livi: Antropometria.
CHAPTER II
CRANIOLOGY
Having finished the study of general biological questions and of the body considered in its entirety, we may now pass on to analyse its separate parts, treating in connection with each of such parts the social and pedagogic questions which may pertain to it.
The parts of the body which we shall take under consideration are: the head, the thorax, the pelvis and the limbs.
The Head.—When we pass from the body as a whole to a more particularised study of the separate parts, it is proper to begin with the head because it is the most important part of the whole body. The older anthropology, and biological and criminal anthropology as well were very largely built up from a study of the head; a study so vast and important that it has come to constitute a separate branch of science: craniology.
The fact is that the characteristics manifested by the cranium are chiefly in the nature of mutations rather than variations, and consequently the anthropological data relating to the cranium correspond more directly to the characteristics of the species, or in the case of man, to the characteristics of race. Hence they are of special interest to the general study of anthropology. But when these imitative characteristics, which are naturally constant and have a purely biological origin, undergo alterations, they are to be explained, not as variations, but as pathological deviations; and for this reason criminal anthropology has drawn a very large part of its means of diagnosis of anomalies and of degeneration from malformations of the cranium.
Furthermore, the cranium together with the vertebral column represents not only the characteristics of species, but also those of the genus; in fact, it corresponds to the cerebro-spinal axis, which is the least variable part of the body throughout the whole series of vertebrates; just as, on the contrary, the limbs represent the most variable part. Indeed, if we study separately the cranio-vertebral system and the limbs, through the whole series of vertebrates, we shall discover gradual alterations in the former, and sudden wide alterations in the latter. The cerebro-spinal axis (and hence the cranio-vertebral system) shows from species to species certain progressive differences that suggest the idea of a gradual sequence of modifications (from the amphioxus to man) to which we could apply the principle, Natura non facit saltus: while the limbs on the contrary, even though they preserve certain obvious analogies to the fundamental anatomic formation of the skeleton, undergo profound modifications—being reduced in certain reptiles to mere rudimentary organs, developing into the wing of the bird, the flying membrane of the bat, and the hand of man.
Since it is not only a characteristic of species and race, but of genus as well, the cranium constitutes one of the most constant anatomical features. For the same reason it is less subject to variations due to environment, and from this point of view offers slight interest to pedagogic anthropology. But since the cranium contains the organ on which the psychic manifestations depend, we have a deep interest in knowing its human characteristics, its phases of development, and its normal limits.