Fashion and fads in bird song

From long-lasting traditions to fleeting fashion and fads – culture is everywhere in our lives, and it relies on our ability to learn from and build on the innovations of others.

For a long time, it was thought that culture was a uniquely human phenomenon. However, over the last decades more and more evidence for culture in animals is accumulating: from tool use in chimpanzees, to foraging techniques in killer whales and of course song in many species of birds. Culture provides a second inheritance system through which these behaviours are transmitted from generation to generation, not through genes, but through social learning.

However, whether animal culture relies on the same processes that also underlie human culture is still an open question. In this project, I propose to study the cultural processes underpinning fashion and fads in bird song using state-of-the-art simulation models in combination with pioneering field experiments.

Bird song is an excellent model to answer questions about cultural behaviour in animals^1,2. Through social learning songs are transmitted over generations and by copying innovations or mistakes, songs change over time: a process called cultural evolution. Interestingly, this pattern of accumulation of modifications in songs has features in common with cumulative cultural evolution (the tendency to accumulate adaptive innovations), often thought to be a core feature of the uniqueness of human culture. While in most bird species this change occurs gradually, in some species changes in songs happen quite abruptly. One of these, the corn bunting (Emberiza calandra) has a particularly unusual pattern of song sharing and transmission. These birds display a system of local song dialects, where all males within a local dialect area (10-40 males) share the same set of songs, but share no songs with males in neighbouring dialect areas³. Moreover, from one year to the next all males in a local area rapidly and concertedly change their songs from last years’ version into an updated version. These cultural dynamics are superficially similar to human fashion or fads and make the corn bunting an excellent model species to study animal fashion cycles:

What processes underlie such an apparently contradictory situation of both conformity (in which all individuals conform to the norm at any one point in time) and periods of plasticity and rapid change? Which social learning strategies could lead to these fashion-like patterns in song sharing? Why do some mutations or innovations spread through a population, but not others? What selection pressures have led to the style of social learning that leads to fads?

In this project, I will combine computer simulation models with song recordings to understand which learning processes and population dynamics can generate animal fashion cycles. I will then reveal the selection pressures underlying the evolution of these cultural dynamics by measuring female preferences for songs, as well as male reproductive success. The use of this approach will not only provide the most in-depth analysis of animal fashions, but it may offer clues about the processes required for the evolution of our own ability for complex culture.