Is cumulative culture restricted to modern humans?

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Modern humans can and do accumulate culture. Primary evidence for this are the artefacts around us, different across different human cultures, which could not be reinvented by individuals working independently of the discoveries of their forebears. The mechanisms of human cultural transmission ensure that successive generations of humans need not reinvent the cultural innovations of their forebears, as earlier achievements are passed down and improved across generations. This is cumulative culture (CC).As adults, we are heavily influenced by the culture in which we grew up; and there is no question that human children learn elements of culture from others. Thus, an important question is at what age - and how - children accumulate the culture of their peers. The PI (Tennie) proposes to investigate this by providing children with raw materials for tool manufacture, in a basic, but unusual, task (e.g. collecting floating objects). Using chains of children, the experiments will test if and how they accumulate culture across "generations" of interaction (child A will perform the test task while child B watches; then child B will be tested while child C watches, and so on). Such a method will answer the question of which learning mechanisms are necessary for tool use CC in general (imitation, emulation - or a mixture of both) since children cannot yet rely on the same rich CC background as adults (who so far have been the focus of such studies).Current evidence suggests that great apes are poor at one particular learning mechanism: imitation. This renders great apes an ideal additional test case for the necessary mechanisms for CC: if imitation is required for CC, then great apes should not show CC. Yet, some great ape tool use has been proposed as cases of CC (e.g., producing "brush tools"). But it may be that unlike human children they do not acquire their tool using skills through imitation. The existence of tool use is not a reliable guide to CC (e.g. woodpecker finches). Great apes may basically re-invent the techniques required for efficient tool use for themselves after observing the outcomes of others actions - this would be emulation learning. The PI has previously termed this learning strategy the "zone of latent solutions", where latent solutions are the techniques that apes succeed in inventing for themselves.In recent years the PI has developed several research paradigms that test the prediction that great apes do not learn so much from one another, and that cases of 'cultural' learning testifies instead only to spontaneous innovations. Of special importance is a study in which he provided naïve apes (gorillas) with the raw materials for behaviours thought to require cultural transmission in the wild (delicate nettle feeding skills). The tested captive gorillas spontaneously invented these behaviours despite never having seen them. Using the same methodology, the PI plans to continue the strategy of providing naïve apes with the raw materials involved in wild "cultural" behaviour. If naïve subjects show this 'wild' behaviour, it cannot be the consequence of CC but only a latent solution. If all putative cultural behaviours in wild great apes turn out to be latent solutions, then human culture may be the consequence of a uniquely human tendency to engage in imitative learning. Emulation alone (as used by great apes) may thus not be sufficient for CC.The proposed project will therefore determine whether nature put great ape - but not human - cultures "on a leash". It has important implications for the way we view early hominid stone tools, some of which the archaeological record shows kept their basic forms for millions of years. The best explanation for this lack of change may be that these tools - as modern great ape tools - were latent solutions.