Bonobo

Female bonobos are individually smaller than males but coalitionally stronger. Unrelated females bond and back each other, and a male's standing derives largely from his mother's. The result is a society with markedly less lethal aggression than chimpanzees — no observed infanticide, no recorded intercommunity killing.

Their entire world range sits inside the arc of the Congo River, which they cannot cross. Roughly a tenth of that range has formal protection, and much of the rest is unsurveyed forest reachable only by river and foot. Almost everything known about wild bonobos comes from a handful of long-term field sites.