Campbell's Monkey

Campbell's monkeys produce alarm calls with a grammatical structure—adding suffixes to root calls that modify their meaning. The 'boom' call indicates non-predator disturbance. Adding '-oo' creates 'boom-oo' which broadens the meaning. 'Krak' indicates leopard; 'krak-oo' indicates general disturbance. This affixation system parallels human language morphology.

The suffix system creates semantic flexibility. Rather than needing separate calls for every situation, Campbell's monkeys combine elements to generate meanings. This combinatorial capacity vastly expands communication possibilities with limited vocabulary—the same advantage human languages gain from morphological rules.

Cross-species comprehension exists. Diana monkeys respond appropriately to Campbell's monkey calls, extracting the semantic content despite species differences. This suggests the semantic system is transparent enough for eavesdroppers to decode. The calls aren't arbitrary symbols but carry meaning accessible across species boundaries.

Call combinations create sentence-like structures. Males produce sequences of different call types that together convey complex information about predator type, location, and urgency. The sequencing follows patterns—not random concatenation. This proto-syntax demonstrates that compositional communication exists outside human language.

For organizations, Campbell's monkeys demonstrate that flexible communication systems beat fixed vocabularies. Morphological rules that modify base meanings create unlimited expression from limited elements—exactly what human language achieves through grammar.