According to Guns, Germs, and Steel, what does the following have to do with the fates of human societies?
According to diamond agricultural innovations spread more quickly from east to west of eurasia's axis than from north to south.
What this has to do with the fate of human society is that it did a great deal to help Eurasian societies to have advantages over other societies in the form of guns, germs, and steel.
Because Eurasia had a long east-west axis, the invention of agriculture could diffuse. This meant that many civilizations could spring up instead of only a few, isolated ones. The fact that there were many civilizations meant that they could all invent various things and then trade them with one another. This meant that they moved ahead much more quickly than any isolated society could.
So, diffusion led to the presence of more civilizations. More civilizations led to more innovation and sharing of innovations. These things led to advantages in technology as well as to the presence of epidemic diseases. The technology and the diseases helped the Eurasians conquer other societies in modern times.