> I have read the book: it explicitly and thoroughly debunks the idea that race was a factor in the development of modern societies. It provides a myriad of geographical and climate-based explanations why the course of history would result societies in the northern hemisphere set the direction of clocks for the globe.

Given that ethnic differences develop alongside migrations into new territories, you'd expect them to be formed by those geographical and climate-based explanations. It's a chicken and egg problem, but it doesn't really help if you're dealing with people who believe in racial superiority, they'll just say "yeah, so we became a super great race because we settled in Whatever Region and they didn't because they didn't".

I believe race is blown way out of proportion by believers, but I found Guns, Germs and Steel to be very hand-wavy and starting from the end, working backwards to tell a story that leads where the author wants it to lead.

As Wikipedia puts it, the academic reaction to the book was "mixed".

How does it show that race differences weren't a factor? Not how does it show that other factors existed, but how does it exclude race?

It shows that other explanations are sufficient and make much more sense. But it's a historical explanation, not a double blind experiment.

Nothing will ever disprove "scientific racism" to people who are racist unfortunately.

That's not a rigorous answer which is possibly why you felt the need to play the racism card at the end.

There's no way to make a rigorous (to the "prove" level) argument from history on racism (or most social issues) because it relies on counter-factuals. Counter-factuals are inherently untestable.

Have you actually read the book? There's nothing about feelings in it, and some of the arguments can be stated as irrefutable facts:

There are more species of animals that can be domesticated in the Eurasian landmass than in Africa, the Americas or Australia. 14 out of the 14 large domesticated species are from Eurasia (including North Africa), with the only exception being the Illama/Alpaca. There isn't a single species of large animal in Sub-Saharan Africa or North America that has been domesticated, even in modern times.

There are more plants suitable for cultivation in Eurasia, and the ones that are turned out to be more useful. Rice, barley, wheat and flax are all Eurasian crops. The only major non-Eurasian crops are Maize and Bananas. The East-West orientation of Eurasia proved a major advantage here, because crops domesticated at one latitude could thrive right across the continent, while in Africa and the Americas crops could be successfully locally but were unable to move North/South because of different climates. In Australia there were zero indigenous candidate crops except the macadamia nut, which is slow growing and hard to grow reliably.

Finally, germs: The larger populations and large trade volume in Eurasia meant Europeans were immune to diseases that killed large numbers of native Americans when they arrived. It seems likely the only disease to go the other way was syphilis - which is a lot less contagious and kills a lot slower than smallpox and measles.

I'll just refer you to my previous comment: There's no way to make a rigorous (to the "prove" level) argument from history on racism.

However, these factors do appear to provide sufficient non-race based evidence to explain the outcome. That's a reasonable way to read the claim that the book "debunks the idea that race was a factor in the development of modern societies".

> The very fact that you listed multiple factors admits that multiple factors may have combined to cause it. It could just as well have included race too.

Since the factors are based around geography, and race is also based around geography you sure would expect to see a correlation!

The explanations in the book give a causal link between geography and outcomes. There will be a large number of other factors correlated with that. A good example is "was beer drunk in country" - countries where beer was drunk were much more successful than countries where it wasn't. Race appears to be the same - dependant on geography, but not part of the causal chain of factors mentioned in the book.