ON THE PKOBLEM OF SEXINO OSTEOMETKIC 
MATERIAL 
By KARL PEARSON, F.R.S. 
It is well known that anthropometric, particularly craniometric measurements 
give frequency series, which for moderate sized populations follow closely the normal 
or Laplace-Gaussian distribution. Measurements of stature, cubit head-length, 
cephalic index, etc., etc., obey with sufficient accuracy for most purposes of science 
the normal law. This statement may with a high degree of certainty be extended 
to practically almost all measurements on the adult skeleton. But a new difficulty 
arises in dealing with the parts of the skeleton : the sexing of the several bones of 
the human body is by no means certain, and this is especially the case when we 
come to deal — not with the cranium or the pelvis but with the long bones. In 
order to get over this difficulty, and to find the constants for each sex, it occurred 
to me some years back when the sexing of the long bones had presented this 
problem very forcibly to workers in my laboratory, that the method of my first 
contribution to the mathematical theory of evolution* might be applied. Namely, 
we might take the unsexed material and assume it to consist of a compound of 
male and female data, the frequency curve for each of these being normal ; the 
two components might then be found in the manner of the paper just referred to. 
The method was especially likely to be successful, when the series was otherwise 
homogeneous, the numbers large and the character dealt with substantially diffe- 
rentiated sexually. Of course the method does not give the sex of each individual 
bone, but I have shown in another memoirf, how four to six characters thus 
resolved form a basis for determining the probable sex of each bone, and this with 
an accuracy which is very probably as great as, or even greater than, anatomical 
appreciation unbased on a system of numerical measurement. 
One of the few objections to the method is the labour involved in the process. 
While the analysis required in the application of the method is nut so severe that 
it has not been applied in a large number of cases by workers in the Biometric 
* Phil. Trans. Vol. 185, A, pp. 71—110. 
t To appear in the next number of this Journal. 
