P. F. Jenkins

P. F. Jenkins appears as an observer of saddleback song whose island study gives concrete form to cultural evolution. His evidence follows songs as they pass between birds, vary through imitation, and sometimes acquire durable new forms: change can be inherited culturally rather than genetically, and a mistaken copy can become the beginning of a tradition.

The Island Song Study

The saddleback lives on islands off New Zealand. On the island where Jenkins worked, the total repertoire comprised about nine distinct songs, but an individual male sang only one or a few. The males formed dialect groups: eight males with neighbouring territories, for example, sang a particular song called the CC song, while other groups sang different songs. Some groups shared more than one song, so the island’s repertoire was distributed among overlapping local traditions rather than repeated identically by every bird.

Comparing fathers’ and sons’ songs, Jenkins found that the patterns were not genetically inherited. Young males were likely to adopt songs from territorial neighbours by imitation, in a process the book compares to the acquisition of human language. The contrast is central to the example: the songs move across generations, but their continuity depends on learning from nearby singers, not on genetic transmission from father to son.

A Song Pool and Cultural Mutation

For most of Jenkins’s observations, the number of songs on the island remained fixed. Young males drew their small repertoires from this shared “song pool,” which functioned as a store of patterns available for imitation. Cultural transmission was therefore both conservative and selective: newcomers learned from the songs already present in their local surroundings.

Jenkins also witnessed the invention of new songs through mistakes in copying old ones. A change in pitch, a repeated or elided note, or a combination of parts from existing songs could produce a novel form. The change was abrupt, but the resulting song could remain stable for years and be accurately transmitted to younger birds. As the new form spread, it could give rise to a recognizable group of similar singers. Jenkins called these origins “cultural mutations”: variation appeared in transmission, and imitation carried the variant forward.

Significance in the Book’s Argument

The saddleback example makes cultural evolution more than an analogy. Song patterns vary, pass between individuals by imitation, and persist through repeated transmission, while new forms can arise and endure without genetic inheritance. Jenkins’s observations thus provide a non-human instance of a process the book says is especially consequential in humans, where language is one among many evolving cultural forms.

The account also clarifies the book’s broader interest in replicators and transmission. Its discussion of genes emphasizes that heredity does not mean a whole organism or a complete blueprint passes unchanged: genetic material is reshuffled, and development depends on complex interactions. Jenkins’s song study offers a distinct route by which patterns persist and change. The analogy between cultural and genetic evolution is useful precisely because it does not collapse them into the same mechanism: saddleback songs evolve by imitation, with a copying error furnishing the variation that can establish a lasting new tradition.