What key factor is thought to drive the evolution of complex social networks in Western Lowland Gorillas?

Relying on seasonally fruiting, unpredictable food sources

The intricate, layered social structure observed in Western Lowland Gorillas is strongly linked to their foraging strategy and the nature of their diet. They depend heavily on tracking and utilizing resources from seasonally fruiting trees, which produce fruit crops that are inherently unpredictable in timing and location. To successfully locate and exploit these high-energy, scattered food sources, collaboration, shared memory, and long-term social networks become highly advantageous. This necessity for collective memory and complex tracking of idiosyncratic food supplies is hypothesized to be the primary evolutionary driver for the development of their sophisticated, multi-tiered social organization, potentially preceding similar complexity in the hominin lineage.