According to Gun, Germs, and Steel, what role did axis orientation play in development?

Axis orientation played a major role in development.  It
allowed technology to diffuse on some continents and not on others.  This allowed more
civilizations to arise on some continents.  This allowed those continents to become
dominant.

A long east-west axis such as that of Eurasia was
essential to development.  Crops that arose in one place could be diffused to other
places and new civilizations could start up using these crops.  These civilizations
could then invent technologies and trade them with one another.  This allowed all of
the civilizations to benefit from the inventions of any given civilization.  Continents
without such axes had less potential to give rise to civilizations that would help one
another develop.

In this way, the orientation of the
continents' axes played a huge role in determining which continents
developed.