Evidence of social learning across symbolic cultural barriers in sperm whales

TL;DR

This study provides quantitative evidence of social learning across cultural boundaries in sperm whales by analyzing their vocalizations, revealing that vocal styles can be shared between clans through social interactions.

Contribution

The paper introduces a novel computational method to model whale vocalizations, demonstrating social learning across clans beyond traditional vocal repertoire distinctions.

Findings

Vocal style-clans align with repertoire-clans.

Sympatry increases vocal style similarity for non-identity codas.

Social learning occurs across cultural boundaries in sperm whales.

Abstract

We provide quantitative evidence suggesting social learning in sperm whales across socio-cultural boundaries, using acoustic data from the Pacific and Atlantic Oceans. Traditionally, sperm whale populations are categorized into clans based on their vocal repertoire: the rhythmically patterned click sequences (codas) that they use. Among these codas, identity codas function as symbolic markers for each clan, accounting for 35-60% of codas they produce. We introduce a computational method to model whale speech, which encodes rhythmic micro-variations within codas, capturing their vocal style. We find that vocal style-clans closely align with repertoire-clans. However, contrary to vocal repertoire, we show that sympatry increases vocal style similarity between clans for non-identity codas, i.e. most codas, suggesting social learning across cultural boundaries. More broadly, this subcoda structure model offers a framework for comparing communication systems in other species, with potential implications for deeper understanding of vocal and cultural transmission within animal societies.