According to Guns, Germs, and Steel, what influences caused technology to differ from place to place?

Diamond argues that geography is the major influence that
causes levels of technological achievement to differ from place to place.  He notes four
major geographical factors that influence this.  Those factors
are:

• Area


• Population


• Ease
  of diffusion


• Onset of food
  production

The first two of these have to do
with the number of people and societies that are available to serve as potential
innovators.  The larger the area and the more people there are, the more inventions can
be discovered.  If diffusion is easy, the technology can be shared.  Finally, early
onset of food production means that A) people can have more time to devote to inventing
things and B) a complex society requires more
technology.

These factors help to determine which places
have high levels of technological development and which do not.