How social learning adds up to a culture: from birdsong to human public opinion

Abstract

Distributed social learning may occur at many temporal and spatial scales, but it rarely adds up to a stable culture. Cultures vary in stability and diversity ( polymorphism), ranging from chaotic or drifting cultures, through cumulative polymorphic cultures, to stable monolithic cultures with high conformity levels. What features can sustain polymorphism, preventing cultures from collapsing into either chaotic or highly conforming states? We investigate this question by integrating studies across two quite separate disciplines: the emergence of song cultures in birds, and the spread of public opinion and social conventions in humans. In songbirds, the learning process has been studied in great detail, while in human studies the structure of social networks has been experimentally manipulated on large scales. In both cases, the manner in which communication signals are compressed and filtered -either during learning or while traveling through the social network -can affect culture polymorphism and stability. We suggest a simple mechanism of a shifting balance between converging and diverging social forces to explain these effects. Understanding social forces that shape cultural evolution might be useful for designing agile communication systems, which are stable and polymorphic enough to promote gradual changes in institutional behavior.

Balanced imitation sustains song culture in zebra finches

“…In the framework of error correction 34 , the developmental question is when and how the vocal learning bird balances between error correction exclusively in reference to tutor sounds to error correction in reference to a state of minimal or maximal sound diversity. Better understanding of this balance and possible transition could reveal the mechanism through which a species speci c level of cultural song diversity is determined 23 . Another observation that requires further study is the recombination of syllable units.…”

“…In reality, however, zebra nch songs remain highly diverse within groups and vary only mildly across them 22 . We do not know if this diversity serves any function in domesticated zebra nches, but high similarity between songs could potentially generate impoverished communication systems that convey little information about individual identity 23,24 . In wild songbirds, across species, and even subspecies, the magnitude of individual song variability differs strongly, often for no apparent reason.…”

Towards an integrated view of vocal development

“…Typically, the studies in this field focus on how the changes in the neural circuitry involved affect the vocal output. The imitative aspect of vocal learning has been studied both at the level of the nervous system (particularly in humans and in songbirds [ 3 ], with almost a complete absence of data for nonhuman mammalian species), as well as at the level of the social interaction required [ 4 ]. Memory, perceptual predispositions, and auditory–motor mappings have been studied in depth, but the role played by the changes in the body structure that generates this behavior has been much less studied.…”

Machine learning reveals cryptic dialects that guide mate choice in a songbird

“…Local song dialects have been identified in bird species with relatively simple songs where individuals show high cultural conformity [5][6][7][8][9][10] . In contrast, the emergence of cultural dialects has been regarded as unlikely [11][12][13] for species with more variable song, such as the zebra finch (Taeniopygia guttata). Instead, it has been proposed that selection for individual recognition and distinctiveness may lead to a complete spread across the space of acoustic and syntactical possibilities [11][12][13][14][15] .…”

“…In contrast, the emergence of cultural dialects has been regarded as unlikely [11][12][13] for species with more variable song, such as the zebra finch (Taeniopygia guttata). Instead, it has been proposed that selection for individual recognition and distinctiveness may lead to a complete spread across the space of acoustic and syntactical possibilities [11][12][13][14][15] . However, another possibility is that analytical limitations have meant that subtle but possibly salient group differences have not yet been discovered in such species.…”