Guns, Germs and Steel is a very researched hypothesis on how societies and technological differences between them evolved. It's main thesis states that environmental factors such as climate, available domesticable organisms, endemic diseases,.. etc. strongly determined our history whereas differences between ethnic groups had very little influence.

Diamond may have posed his theories with a bit too much confidence, giving the impression that this synthesis has any scientific consensus behind it. It is however based on cited evidence and debatable evidence is discussed as such.