What makes a cultural behaviour cumulative rather than just socially learned?
Cumulative culture means that a behaviour is not simply copied from one animal to another but is built up over time: one individual's innovation is added to an existing technique, and later individuals inherit the improved version. This is different from a single socially learned habit that stays the same across generations. The question is therefore not only whether animals learn from each other, but whether their traditions accumulate modifications.
A theoretical review argues that the origins of cumulative culture in non-human animals may not depend mainly on how faithfully social transmission copies a behaviour [2]. That matters because it shifts attention from copying accuracy alone to the processes by which innovations are modified and combined. In other words, an animal can be a good copier and still lack cumulative culture if new modifications are not retained and passed on.
Which experimental designs can separate cumulative from non-cumulative transmission?
The clearest experimental approach is to use a task that cannot be solved by a single innovation, so that success requires combining or building on earlier steps. In a chimpanzee study, researchers used an experimental design aimed at distinguishing cumulative from non-cumulative cultural transmission [3]. The finding that young chimpanzees tended to stick to their initial techniques is important because it suggests a limit on the step-by-step improvement that cumulative culture requires [3].
This kind of design works by making the task's difficulty the test: if animals can only succeed by adding one modification to another over time, then success is evidence of cumulative transmission, while failure or fixation on a first method points away from it. The chimpanzee result is therefore both an empirical finding and a template for how to ask the question in other species [3].
What does long-term field evidence add?
Field records can show whether a behaviour becomes more complex over time, which is one expected signature of cumulative culture. In humpback whales, nine years of song data showed that song complexity increased over time [4]. The authors suggest that this increase may reflect the collective contributions of different animals' innovations to cumulative cultural change [4]. That is a possible interpretation rather than a proven cause, because an increase in complexity could in principle arise without cumulative transmission.
Primate research also points to a potential case of cumulative culture in a non-human species, alongside evidence about selective social learning and transmission biases [5]. The value of such cases is that they identify what cumulative culture might look like in the wild, but they do not by themselves rule out non-cumulative explanations. A field pattern of increasing complexity is therefore best treated as consistent with cumulative culture rather than as decisive proof.
How does collective knowledge fit in, and what is still unresolved?
One broader review examines the emergence of collective knowledge and cumulative culture across animals, humans, and machines, and notes that collective animal knowledge may in turn provide evidence of cumulative culture [1]. This widens the question from individual copying to group-level accumulation, but it does not supply a specific design for telling cumulative from non-cumulative transmission [1].
The unresolved issue is that different lines of evidence answer different parts of the question. Experiments with multi-step tasks can test whether animals build on earlier techniques [3], while long-term field records can show whether complexity rises over time [4]. Neither approach alone settles the case, and the theoretical point that transmission fidelity may not be the key factor means that a species can show strong social learning without cumulative culture [2].
Sources used in this answer
The emergence of collective knowledge and cumulative culture in animals, humans and machines
The review examines collective knowledge and cumulative culture across animals, humans, and machines, and notes that collective animal knowledge may provide evidence of cumulative culture, but it does not detail designs to distinguish cumulative from non-cumulative transmission.
All innovations are equal, but some more than others:(re) integrating modification processes to the origins of cumulative culture
The paper argues that the origins of cumulative culture in non-human animals may not reside mainly in the fidelity of social transmission, offering a theoretical perspective rather than specific experimental designs.
Chimpanzees (Pan troglodytes) and the question of cumulative culture: an experimental approach
An experimental study of chimpanzees found that young chimpanzees tended to stick to initial techniques, which may limit cumulative social learning, and it outlines an experimental design to differentiate cumulative from non-cumulative cultural transmission.
When does cultural evolution become cumulative culture? A case study of humpback whale song
Analysis of nine years of humpback whale song data showed that song complexity increased over time, which the authors suggest may illustrate cumulative cultural change through the collective contributions of different animals' innovations.
Culture and selective social learning in wild and captive primates
The review examines social learning and selective transmission in wild and captive primates and identifies a putative case of cumulative culture in a non-human primate, without addressing designs to distinguish cumulative from non-cumulative transmission.