resources being abundant doesn’t make people fight less
Um, yes it does? Wars are fought over resources.
wars are also fuelled by resources, and population levels rise with abundance, so cultural factors tend to outweigh resource availability.
This seems like kind of a cheat, though! Abundance is relative to need, so if population levels have increase to match then there isn’t really abundance any longer. But abundance implies slack, so you certainly would expect it to have a dampening effect on war, because the alternative to not having war is better in that situation. Once population catches up with abundance the slack is gone, and then you may be back to the same position as you would have with no abundance, but you won’t necessarily have more fighting per capita.
The only situation I can think of where abundance wouldn’t make people fight less is when a resource is extremely scarce and valuable, but locally abundant within a small enough territory to hold – like a guano island, or a key mountain pass. But even there it’s really a situation of scarcity that drives the conflict.
Azar Gat actually talks a lot about this in War in Human Civilization.
With regards specifically to humans in hunting-gathering and comparable civilizations – the evidence seems to pan out such that, in fact, abundance correlates directly with greater violence.
The basic engine seems to be:
In places/times characterized by great scarcity, you really do need to devote all your resources to the very-shortest-term kind of survival. Even raiding is a risk that generally isn’t worth it. If you get killed, well, you get killed, and likely you’re so poor that you have no wherewithal to develop much of an edge over your enemy to prevent this. Even if you just get driven off, you’re fucked, because you put all that energy into the raid instead of into keeping yourself alive. And straight-up winning doesn’t help you that much either, because this is Poverty World and your enemy is just as poor as you are.
A richer environment means that you can (a) raid someone with something worth taking and (b) invest in battle capability. You can also amass enough resources that doing something like “supporting multiple reproductive partners” becomes viable.
No commentary at present on how this logic expands to non-primitive contexts.