Metcalf: Evolution and Man 
evolution. Is man mutating today? 
Does he present stable variations which 
may be utilized to secure his evolution 
to a higher condition? The various 
species of animals and plants differ in 
the degree of their mutation. The 
domestic goose has developed few breeds 
‘ because it presents few and _ slight 
mutations from which to breed new 
forms. The common pigeon,® on the 
other hand, has evolved under artificial 
selection into a host of very divergent 
breeds. To which type does man 
belong? Is he mutating or not? By 
his fruits we can know him. Does the 
species show high diversification into 
races, or has it remained fairly uniform? 
SEVERAL SPECIES OF MAN 
We have evidence of at least two 
species of true men, the Néeanderthaloid 
species, Homo neanderthalensis, with 
perhaps more than one race, now wholly 
extinct, and Homo sapiens, with at least 
three subspecies represented in Europe 
and with numerous very divergent 
races scattered throughout the habitable 
earth. To reach this condition of great 
diversity, mutation must have been 
frequent and considerable in degree 
in the past, and we have no reason to 
suppose it less today. Few species of 
organism show more abundant or more 
extreme mutation thanman. The races 
of men differ not only in such physical 
characteristics as stature, color, shape of 
cranium and of face; form of features; 
color, position and shape of eyes; color, 
shape and coarseness of hair; relative 
length and size of different portions of 
skeleton; form and size of teeth; and 
numerous others—they differ no less 
in mental qualities, in intellectual abil- 
ity, in educability, in disposition. Yes, 
mutation, physical and mental, has been 
prevalent in the past and is doubtless 
continuing today. 
Much of the change we see appearing 
in human families from generation to 
generation may be but the resolution and 
5It is possible the domestic pigeon is of hybrid origin. 
363 
recombination of qualities already in 
this highly hybrid stock, but the 
evidence from his past shows almost 
beyond question that new features must 
be appearing through mutation and 
joining the huge jumble of qualities 
which are reshuffled with every marri- 
age. Along with the ancestral qualities 
and the new mutations, all heritable, 
are of course numerous non-heritable 
features which have arisen by variation 
of the non-stable type. The condition 
is one of great complexity, difficult of 
analysis even if we were free to use 
experimental breeding. Without ex- 
perimental breeding, using only observa- 
tion of chance matings, as is necessary 
under the conditions presented by 
human society, the analysis of the condi- 
tions presented seems nearly hopeless. 
We shall learn something, much in time, 
but it will be slow progress at the best. 
New qualities which arise in any 
species are often slight at first, their 
value appearing only after generations 
of orthogenic intensification. In experi- 
mental breeding many such must escape 
notice and be lost. Among human- 
kind any quality to be repellant or 
attractive in influencing marriage must 
be well developed and prominent. 
Marriage selection, therefore, cannot 
act upon any new quality unless it be 
well developed at its origin (what 
breeders of animals and plants call a 
“sport’’) or until, if slight at first, it be 
given probably many generations to 
develop and become prominent. We 
should note further that by the time 
adult life is reached every individual 
has been so modified by education and 
by self-training that his inborn character 
is obscured, so that he may be chosen 
in marriage on the basis of character 
which in considerable degree is ‘‘ac- 
quired” and therefore is not transmissi- 
ble. The subject is extremely complex. 
Not even its outlines can be indicated 
in this paper. 
What conclusion, if any, can we 
Better examples of non-mutating 
and mutating stocks would be the potato, which has shown little divergence under prolonged 
cultivation, and the wild cabbage (Brassica oleracea) which has been developed by selection of 
its mutants into the domesticated cabbage, kale, Brussels sprouts, cauliflower, kohl rabi, and 
Swedish turnip, leaf, flower and stem all having been greatly modified. 
6 Cf. Osborn, Henry Fairfield, ‘‘Men of the Old Stone Age,’’ New York, 1915. 
