CHAPTER: XI 
KINSHIP AND ADAPTATION 
163. The problem of origins. Kinship among living 
things implies a common origin. We know that kin always 
resemble one another more or less closely, and this likeness 
we attribute to their inheriting similar features from the 
same ancestor. Two individuals which differ from each 
other no more than do offspring of the same parents, we re- 
gard as belonging to the same species; and because of such 
likeness among the members of a species we feel sure of their 
having descended from an original ancestor or ancestors 
which had essentially the same characteristics. 
No one doubts that all the kidney-bean plants in the world 
are the descendants of a plant or plants having the charac- 
teristic features of a kidney-bean; but, as we have seen, 
there are numerous varieties of this species which differ 
strikingly from one another; often more widely than do many 
species of the same genus. Why then may not all the species 
of beans be descended from a more remote ancestor, and so 
be as truly akin as the members of one species? And if the 
species of this genus are thus related why not also, though in 
less degree, the genera of the pulse family, the families of the 
rose order, the orders of the case-seed class, the classes of the 
seedwort branch, the branches of the vegetable kingdom, and, 
indeed, all groups of plants and animals according to their 
several degrees of resemblance? Why may it not be true that 
a natural system of classification expresses kinship? 
To some readers it may appear profitless to pursue in- 
quiries so remote, and they naturally ask, How can we know 
or why should we care about the origin of living things? Our 
answer must be that while of course we cannot know about 
this absolutely, we may be more or less sure that our conclu- 
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