Directional Cultural Change by Modification and Replacement of Memes

Abstract

Evolutionary approaches to culture remain contentious. A source of contention is that cultural mutation may be substantial and, if it drives cultural change, then current evolutionary models are not adequate. But we lack studies quantifying the contribution of mutations to directional cultural change. We estimated the contribution of one type of cultural mutations-modification of memes-to directional cultural change using an amenable study system: learned birdsongs in a species that recently entered an urban habitat. Many songbirds have higher minimum song frequency in cities, to alleviate masking by low-frequency noise. We estimated that the input of meme modifications in an urban songbird population explains about half the extent of the population divergence in song frequency. This contribution of cultural mutations is large, but insufficient to explain the entire population divergence. The remaining divergence is due to selection of memes or creation of new memes. We conclude that the input of cultural mutations can be quantitatively important, unlike in genetic evolution, and that it operates together with other mechanisms of cultural evolution. For this and other traits, in which the input of cultural mutations might be important, quantitative studies of cultural mutation are necessary to calibrate realistic models of cultural evolution.K E Y W O R D S : Birdsong, culture, evolutionary models, memes.

Boldness behavior and stress physiology in a novel urban environment suggest rapid correlated evolutionary adaptation

“…Numerous behavioral differences between the colonist and an ancestral range population have been documented, including earlier onset of reproduction , loss of migratory behavior (Yeh 2004), reduced male territorial responses (Newman et al 2006), altered song frequencies (Slabbekoorn et al, 2007;Cardoso and Atwell 2011), and reduced plumage ornamentation (a difference which was shown to be genetic; Yeh 2004). We have also observed that colonist birds are quicker to approach novel objects, such as food bait, walk-in traps, or mist nets (J.W.A., anecdotal observation).…”

Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

“…A comparative study revealed that the link between geographical patterns of noise distribution and song frequency are especially strong for species that learn their songs through social experience [20]. However, although historical changes to population repertoires suggest that exposure to urban noise can influence loss or retention of different song types [21,22], to date no empirical data have shown that the degree to which songs are masked affects repertoire retention within individuals [23,24], nor is there any evidence that birds need experience to learn which song frequencies work best under different circumstances.…”

Parallel evolutionary forces influence the evolution of male and female songs in a tropical songbird

“…Under both scenarios, songs can diverge quickly and independently of genetic changes (Ellers & Slabbekoorn, ). Furthermore, individual mating preferences may not only influence changes in song structure, but also the song types that are used in populations (Cardoso & Atwell, ). For example, some tropical species follow duet codes when coordinating their songs to produce duets with their mates (Logue, ; Templeton et al ., ).…”