sible in tropical and sub-tropical latitudes does
away with the idea of necessity as the mother of invention in those
parts of the world it becomes difficult to see how tool-using man, who
is generally supposed to have originated somewhere in the warm belts,
came to take the first and the most difficult steps in the upward
progress where there was so little, if any, incentive to that sustained
effort and concentration of the mind which is required for the thinking
out of the most difficult of all thoughts, the first principles of any
art or craft. Why, we may well ask, should the primitive African have
worried about cultivating the soil where edible roots and berries
abounded? Why should he have bothered about making fire where there was
no need of artificial warmth or for the cooking of food? Why should he
have cudgeled his brains to fashion weapons and to contrive snares for
the killing of game of which he was in no more need than his vegetarian
cousins, the anthropoid apes? Why should there have been progress where
the environment provided no stimuli therefore, in other words, why
should primitive man have moved forward where indulgent nature allowed
him to stand still?

If we believe, with Darwin and other students, that our primitive
ancestors emerged from somewhere within the warm zones, we cannot avoid
the difficulty of reconciling that supposition with the theory that
civilisation is in the first instance the result of a stimulating
environment. If on the other hand, we surmise that _homo sapiens_
originated in the colder parts of the world we still have to account for
the fact that his further progress was made not in those parts but in
warmer latitudes where a genial climate afforded no apparent provocation
for continued effort in the way of invention and general development.

It would seem that the innate tendency to conservatism latent in man,
the disposition to leave things as they are and to stick to the familiar
devil rather than fly to unknown gods, is in itself sufficient to
account for those lapses in mass-achievement and those long periods of
stagnation which mark the course of mankind everywhere. We see how Egypt
hovered for centuries on the brink of the discovery of the alphabet but
never attained thereto. The exponents of the so-called "pulsatory
hypothesis" can hardly claim that a change in the climate will explain
the fact seeing that the neighbouring people were able to accomplish
this great fe