1 I, BUREAU OF AMERICAN ETHNOLOGY [utr 33 
although their application may prove arduous and is not certain of | 
affording satisfactory results. 
A geologically ancient bone may be safely expected to show some 
degree of infiltration and replacement of its constituents by mineral | 
matter, while modern bones are generally little changed; yet there | 
exist in some localities conditions which greatly retard or facilitate 
the processes of mineralization, so that ancient bones may show but | 
little evidence of fossilization, while, on the other hand, undoubtedly | 
recent bones may have undergone decided change. The latter con- | 
dition is far more frequent. There is a possibility that the kind or | 
the degree of the change may make it practicable to distinguish | 
between recent and ancient fossilization: but there are as yet no 
satisfactory means of testing this matter. 
Somatologically, the bones, and particularly the skull, of early man 
may be confidently expected to show some differences from those of 
modern man, especially in the direction of lesser differentiation. 
Unfortunately the knowledge of the osseous structures of early man 
in other parts of the world is still meager, and this lack of informa- 
tion is felt very keenly. We do not know as yet whether the human 
beings of the geological period just before the recent differed so 
from the present man that even the extreme individual variations 
in the two periods (the most advanced evolutionally in the old and 
the least advanced among modern individuals) would stand appre- 
clably apart. Very likely they overlap and dovetail considerably. 
Yet the difficulties which may attend the separation on the morpho- 
logical basis of ancient from recent man should not be insuperable. 
If a find should consist of a series of well-preserved skulls or skeletons 
geologically ancient and of a similarly well-preserved series of skulls 
or skeletons of recent man, it is the firm conviction of the writer that 
in a large majority, if not in all, of the cases, their separation would 
be practicable. The greater the number of male adult normal, and 
in no way deformed, crania in each find, the easier it would become to 
make the necessary distinctions: and it may be safely assumed also 
that the greater the separation of the two groups in time the more 
distinet would be the somatological differences, 
There is no such thing as absolute stability in any human strue- 
ture. Every organic feature, of whatever consistency or importance, 
is the result of all the factors by which it was affected. With the 
skeletal parts by far the strongest of these-factors, in itselfa very com- 
posite one, is the potentiality of heredity, next to which in impor- 
tance comes habitual muscular action, particularly muscular use due 
to long-established habits of whole groups of people. Heredity, how- 
ever, especially in so far as it applies to the latest acquired charac- 
teristics of the skeleton, is subject to incidental irregularities as well 
as to gradual modifications. Habits of muscle action, on the other 
