Birds’ intruder alert hints at how sounds took on new meanings

The relationship between sounds in words and their meaning is thought to be mostly arbitrary. Some linguists and behavioural ecologists, however, argue that the instinctive vocal responses that humans and animals make — a cry or laugh, for instance — served as the foundation on which language evolved, as new meanings became associated with them. Feeney and colleagues explore learnt sound–meaning associations in birds (W. E. Feeney et al. Nature Ecol. Evol. https://doi.org/p78m; 2025).