CHAPTER VII 
Tue Evo.uTion oF THE HumMAN INTELLECT! 
To the intelligent man with an interest in humah nature 
it must often appear strange that so much of the energy of 
the scientific world has been spent on the study of the body 
and so little on the study of the mind. ‘The greatest thing 
in man is mind,’ he might say, ‘yet the least studied.’ Es- 
pecially remarkable seems the rarity of efforts to trace the 
evolution of the human intellect from that of the lower ani- 
mals. Since Darwin’s discovery, the beasts of the field, 
the fowl of the air and the fish of the sea have been ex- 
amined with infinite pains by hundreds of workers in the 
effort to trace our physical genealogy, and with consummate 
success; yet few and far between have been the efforts to 
find the origins of intellect and trace its progress up to hu- 
man faculty. And none of them has achieved any secure 
success. 
It may be premature to try again, but a somewhat ex- 
tended series of studies of the intelligent behavior of fishes, 
reptiles, birds and mammals, including the monkeys, which 
it has been my lot to carry out during the last five years, has 
brought results which seem to throw light on the problem 
and to suggest its solution.” 
Experiments have been made on fishes, reptiles, birds and 
various mammals, notably dogs, cats, mice and monkeys, 
to see how they learned to do certain simple things in order 
' This chapter appeared originally in the Popular Science Monthly, Noy., 
IgoI. 
282 
