When does cultural evolution become cumulative culture? A case study of humpback whale song

Abstract

Culture presents a second inheritance system by which innovations can be transmitted between generations and among individuals. Some vocal behaviours present compelling examples of cultural evolution. Where modifications accumulate over time, such a process can become cumulative cultural evolution. The existence of cumulative cultural evolution in non-human animals is controversial. When physical products of such a process do not exist, modifications may not be clearly visible over time. Here, we investigate whether the constantly evolving songs of humpback whales ( Megaptera novaeangliae ) are indicative of cumulative cultural evolution. Using nine years of song data recorded from the New Caledonian humpback whale population, we quantified song evolution and complexity, and formally evaluated this process in light of criteria for cumulative cultural evolution. Song accumulates changes shown by an increase in complexity, but this process is punctuated by rapid loss of song material. While such changes tentatively satisfy the core criteria for cumulative cultural evolution, this claim hinges on the assumption that novel songs are preferred by females. While parsimonious, until such time as studies can link fitness benefits (reproductive success) to individual singers, any claims that humpback whale song evolution represents a form of cumulative cultural evolution may remain open to interpretation. This article is part of a discussion meeting issue ‘The emergence of collective knowledge and cumulative culture in animals, humans and machines’.

The emergence of collective knowledge and cumulative culture in animals, humans and machines

“…Recognizing this, but going far beyond it, articles in this issue address the significance of cases where collective knowledge exists only at the level of the collective, and not in any one individual. The partial or variant knowledge of different individuals that this implies may be distributed across a population in space, and/or over time, with subsequent combinations thence leading to innovations that can drive CCE [ 82 , 93 , 153 – 155 , 159 , 160 ]. Studies are progressively revealing that how these effects play out may be shaped by numerous interacting factors including the form of social structures and networks [ 93 , 159 , 160 ], relationships between individuals such as in degree of tolerance [ 153 ] or coordination [ 157 ], adaptive biases in model selection such as conformity [ 153 , 163 ], and the socio-cognitive capabilities of participant individuals, such as theory of mind [ 29 , 158 ] and inventiveness.…”

“…All such cases are suggestive of collective contributions of different animals' innovations to cumulative cultural change, across significant time-depths. That of the humpback whales is pursued in greater depth in this issue [ 82 ].…”

The origins of human cumulative culture: from the foraging niche to collective intelligence

“…It has been shown that culture can relax or increase selection pressures and favour adaptations in various species [ 140 , 141 ]. However, the reasons for the transition from a facultative inheritance system to dependence on a system of gene-culture coevolution in hominins remain a puzzle.…”

Collective minds: social network topology shapes collective cognition

“…While the burgeoning research on social learning across the species points at cultural evolution and collective knowledge (see Garland et al . [ 62 ]; Gruber et al . [ 63 ]; Whiten et al [ 64 ]; Wild et al .…”