SUMMARY AND CONCLUSION 315 
we concluded that their analogical method was unsatisfactory, 
also that the biometric method of the Galton Eugenics Laboratory 
had not as yet yielded conclusive evidence as to the relative in- 
fluence of “ nature” and “nurture,” because the data were 
unreliable and because of the inherent difficulty of separating 
these two factors. Evidence brought forward in later chapters 
has tended to confirm this conclusion and to leave us in uncer- 
tainty as to whether or not progress from the far distant period of 
the Neanderthal and Cro-Magnon types of man has been in native 
mental ability or merely in somatic variations in the line of or- 
ganic adaptation to geographical environment, and in acquired 
intellectual and moral qualities transmitted by social heredity. 
The arguments of the neo-Darwinian sociologists are too largely 
deductive and analogical to be conclusive, whereas at least some 
of the evidence produced by the environmental school is inductive 
and indisputable. The former to a large extent have made the 
cardinal mistake of assuming that the different races of mankind 
are analogous to biological species whereas at present the con- 
sensus of opinion is that there is but one species, while the term 
“race” has no definite connotation. Evidence concerning the 
difference in social instincts, keenness of sense perception, and 
intellectual and emotional qualities between primitive and 
modern man is so conflicting as to counsel moderation of state- 
ment rather than dogmatism. The evidence on the whole, how- 
ever, indicates that as there have been somatic variations mak- 
ing for better adaptation to, life conditions, especially in the 
decrease in the size of the mandibles, in pigmentation and accli- 
mation, so there have been variations in the nervous system 
and brain tissue making for greater adaptation to the conditions 
of existence and success imposed by modern life in civilized 
nations. Differences in individuals are unquestioned, but when 
the group is made the sociological unit the standard of ability is no 
longer individual but social, and we have no sure word concerning 
the native ability of the average in any civilized nation today as 
compared with the average in any primitive group now extant or 
that ever existed. No two groups come into competition now, 
and never have, so far as we know, under such conditions that we 
