Roy R. Peterson

Densities of Bones of White and Negro Skeletons

The densitiesSee Equation in the PDF fileof the cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacra, ribs, humeri, radii, ulnae, femora, and tibiae from eighty adult skeletons were determined. The skeletons were derived equally from American whites and Negroes of both sexes, each group w

The relationship of ash weight and organic weight of human skeletons.

One hundred twenty adult skeletons, equally divided among white and Negro skeletons of both sexes were ashed. The weight of the ash in terms of per cent of the dry, fat-free weight of the bones was determined for the total skeleton and for twenty subdivisions of each skeleton (mandible, cranium, humeri, radii, ulnae, femora, tibiae, fibulae, clavicles, scapulae, hand bones, patellae, foot bones, hip bones, ribs of both sides; four segments of the vertebral column, and sternum). The resultant determinations of percentage ash weight were analyzed statistically to determine possible effects of age, sex, race, and type of bone (that is, ratio of compact to cancellous substance). It was found that: 1. The percentage ash weight of neither the total skeleton nor any of its twenty subdivisions was affected by age in any sex-race group; 2. The individual percentage ash weights of each bone series did not vary symmetrically around the mean but had an excessive scatter of low values with the scatter increasing as the means decreased; 3. The twenty subdivisions had approximately the same rank order of percentage ash weight among the thirty skeletons of each sex-race group; 4. The ratio of inorganic to organic substance within the bones was constant except for random variation in the cranium, humeri, fibulae, radii, ulnae, femora, tibiae, patellae, and foot bones; this ratio showed an increase with increasing organic weight in the mandible series and a decrease with increasing organic weight in all other Series; 5. The mean percentage ash weight of all subdivisions except mandible, eranium, humeri and ulnae, and possibly the total skeleton, was significantly higher in males than in females; 6. The mean percentage ash weight of eight of the twenty bone series (clavicles, scapulae, hand bones, ribs, thoracic vertebrae, lumbar vertebrae, sacrum, and sternum) was significantly higher in Negro than in white skeletons; 7. The order of the skeletal subdivisions arranged according to decreasing means of percentage ash weight and according to decreasing ratios (estimated) of compact to cancellous substance was very nearly the same in each sex-race group; 8. In all sex-race groups the means percentage ash weight of the mandible was significantly higher than that of any other subdivision of the skeleton; the mean of the femora series was the lowest of the long-limb bones and was significantly lower than the means of the ulnae, radii, and fibulae; the mean percentage ash weights of the hip bones, ribs, and cervical vertebrae were higher than those of time other vertebral segments; and the mean of the sternum (except in the Negro male group) was lower than that of any other subdivision of the skeleton.

SOME VARIABLE FACTORS IN THE ADULT SKELETON

Variability in the structure of the human body is a well recognized principle. For many years anatomists and physical anthropologists have been engaged both in the statistical estimation of the frequency of particular variations within a given population and also in the assessment of the range of variation between different populations, together with the possible genetic and environmental factors which may have contributed to such variations. For several reasons many of these studies have involved the skeleton: It is easily preserved and is thus the most suitable and the most generally available anatomical structure for comparisons between different periods of time and environments, and furthermore the skeleton lends itself most readily to quantitative study. Two examples, both of which concern the skeleton, may be given to illustrate the use of statistical techniques in a problem of variation within given populations. In the first of these, the variation in the relationship between stature and the length of the long bones of the limbs was studied with a view to estimating the stature of a n individual during life from the length of the long bones examined post-mortem. As early as 1888 Rollet presented the results of a study in the form of a table showing the average length of a given bone from those cadavers which had the same stature. The subjects studied were 50 male and 50 female French cadavers with a wide age range (24 to 99 years). Some years later (1892 and 1893), Manouvrier examined the data provided by Rollet and excluded those subjects of 60 years of age and over because of the effect of “old age” on the length of the trunk, leaving 24 males and 25 females. On this basis he drafted a table giving the average stature of those cadavers which presented long bones of the same length. As might be expected these two methods d o not provide values which are interchangeable. At the end of the century (1899) Pearson reexamined the data from all of Rollet’s cases statistically to determine regression formulae for the estimation of stature. Pearson was fully aware of the limitations of his study, the paucity of cases, the possible effect of ageing on stature, and the lack of refinement in the measurements (e.g., the lapse of time after death when stature was measured, and the moist or dry state of the bones at the time of measurement), and pointed out that the formulae he had derived from the available data of French cadavers should be applied to other races with great caution. Thirty years later he was to state quite explicitly that any formula may be expected to be more reliable when applied to skeletal material of the race from which it was derived than to a second race. The occasion for this firm stand was the publication of a paper by Stevenson (1929) reporting a different series of regression formulae based on 48 Northern Chinese male cadavers and comparing the results with those obtained by Pearson from the French data. A somewhat different approach to the problem was taken by Breitinger in 1937. By measuring bone length and stature in a large number of healthy subjects in early adulthood (2400 German males, average age 26 years) the weaknesses inherent in Pearson’s study were obviated, but at the cost of some accuracy, since the length of the bones had to be estimated from measurements between superficial bony prominences.