The Descent of Man

Mus coninga to its superior cunning; and this
latter quality may probably be attributed to the
habitual exercise of all its faculties in avoiding
extirpation by man, as well as to nearly all the
less cunning or weak-minded rats having been
continuously destroyed by him. It is, however,
possible that the success of the common rat
may be due to its having possessed greater
cunning than its fellow- species, before it became
associated with man. To maintain, independently
of any direct evidence, that no animal
during the course of ages has progressed in
intellect or other mental faculties, is to beg the
question of the evolution of species. We have
seen that, according to Lartet, existing mammals
belonging to several orders have larger
brains than their ancient tertiary prototypes.
It has often been said that no animal uses any
tool; but the chimpanzee in a state of nature
cracks a native fruit, somewhat like a walnut,
with a stone. (37. Savage and Wyman in 'Boston