[Depurator]

Isn't it quite naive to use a calculation of the path of least resistance to account for travel costs which the whole argument relies upon? Early civilizations would settle close to rivers and travel on th rivers and along the coasts. It seems like this model does not take this into account.

So when they calculate differences in environmental barriers across continents, it seems important to take water ways into account, which would lead to eurasia having an upper hand over at least NA and Africa. I'm not saying that Diamonds original argument holds, and its great that they try to test the hypothesis.

[hwillis]

> Early civilizations would settle close to rivers and travel on th rivers and along the coasts. It seems like this model does not take this into account.

https://static.cambridge.org/content/id/urn%3Acambridge.org%...

The path cost is dependent on the aridity of the path. They also used examples that specifically contradict your assertion- For instance they looked at an agricultural origin in Ethiopia which should have had easy access all the way to Egypt because of the Nile river. Why didn't culture spread from there instead of from Mesopotamia or Egypt, where those civilizations are at the end of their rivers and don't get any travel benefit?