True, but there is no evidence of anything like that until just a few thousand years ago. Of course some of that may have been related to increasing population density, natural disasters altering the food supply, etc., I think that it is mostly accounted for by a changing social dynamic - going from largely non-hierarchical enclaves that valued and honored personal autonomy to ones based in male led dominance-hierarchies (patriarchy). There've even been some studies that indicate that this sort inequality spread precisely because it was so disruptive -driving migration and either over-running or encompassing egalitarian communities.

https://www.newscientist.com/article/dn22071-inequality-why-egalitarian-societies-died-out/