Environmental Determinism and its problems.

In Guns, Germs and Steel, Diamond argues that Eurasian civilization has conquered and dominated over much of our modern world not due to the product of genetics, but through environmental factors. The opportunities and necessity of the Eurasian situation have allowed their civilization to exceed beyond the necessity of superior intelligence. Consequently, the Eurasian condition resulted from a chain of developments that were only made possible by selective environmental conditions. Because Eurasia had a greater availability of suitable plants and animals for domestication, they were able to bring about an earlier advantage in comparison to other people. 

Diamond seems keen towards reviving the theory of environmental determinism. It is the view that the physical environment sets limits on human environment. It is quite the fundamentalist argument where physical geography and the climate influences the psychological mindset of people. Therein defining their behavior and culture. While this idea might have some examples where it fits in greatly such as with Native American's whose environment completely dominates their culture and behavior regardless of those activities' functionalities. However, you also get cases where the theory doesn't work such as in tropical climates where a view of the physical environment is said to cause lazy, relaxed and promiscuous attitudes. And, also falsely believed, is the after thought that the variability of weather in the middle latitudes leads to more determined and driven work ethics. 

As previously stated, Diamond seems keen on bringing this theory back to life, but which for one is very wrongly directed. Furthermore, he doesn't seem to take too far into account human evolution and the migrations of certain groups of people into Eurasia, which very well could happen much faster than their relative evolutionary progress towards adapting to their environments. 

Here is some on the theory of environmental determinism and why it is so controversial:

http://geography.about.com/od/culturalgeography/a/envdeterminism.htm