120 
THE DESCENT OF MAN. 
Part I. 
time, the femora to the tibiae were as 244 to 230 ; and 
in three Negroes as 258 to 241. The humerus is like- 
wise shorter relatively to the forearm. This shortening 
of that part of the limb which is nearest to the body, 
appears to be, as suggested to me by Mr. Forbes, a case 
of compensation in relation with the greatly increased 
length of the trunk. The Aymaras present some other 
singular points of structure, for instance, the very small 
projection of the heel. 
These men are so thoroughly acclimatised to their 
cold and lofty abode, that when formerly carried down 
by the Spaniards to the low Eastern plains, and when 
now tempted down by high wages to the gold-washings, 
they suffer a frightful rate of mortality. Nevertheless 
Mr. Forbes found a few pure families which had sur- 
vived during two generations ; and he observed that 
they still inherited their characteristic peculiarities. 
But it was manifest, even without measurement, that 
these peculiarities had all decreased ; and on measure- 
ment their bodies were found not to be so much elon- 
gated as those of the men on the high plateau ; whilst 
their femora had become somewhat lengthened, as had 
their tibiae but in a less degree. The actual measure- 
ments may be seen by consulting Mr. Forbes’ memoir. 
From these valuable observations, there can, I think, 
be no doubt that residence during many generations at 
a great elevation tends, both directly and indirectly, to 
induce inherited modifications in the proportions of tho 
body. 33 
Although man may not have been much modified 
during the latter stages of his existence through the 
33 Dr. Wilckens (‘ Landwirthschaft. Woclienblatt,’ No. 10, 1869) 
has lately published an interesting essay shewing how domestic 
animals, which live in mountainous regions, have their frames 
modified. 
