Who’s got rhythm? And why are we such musical, chatty animals? Human music and speech are peculiar behaviours from an evolutionary biology perspective. Notably, they both feature a rhythmic component. Many hypotheses try to explain the origins of our rhythmic capacities, but few are empirically tested and compared. Neither brains nor cognition fossilize, and lacking a time machine, the comparative approach provides a powerful tool to tap into human (pre)history. Notably, behaviours that are homologous or analogous to human rhythm can be found across a few animal species and developmental stages. Hence, investigating rhythm across species is not a zoological endeavour; it is key to unveil when the building blocks of rhythm appeared in human evolution. In this talk, I will introduce the major hypotheses for the evolution of rhythmic capacities in humans and other animals, which link acoustic rhythms to vocal learning, gait, breathing, or group coordination. I will suggest how integrating approaches from ethology, psychology, neuroscience, modelling, and physiology is needed to obtain a full picture. I will then zoom in on some crucial species which are key to test alternative hypotheses on rhythm origins. I will present data from marine mammals and primates (including humans), suggesting that cross-species rhythm research should include ecologically-relevant setups, combining strengths from human cognitive neuroscience and behavioural ecology. These results suggest that, while the full package may be uniquely human due to an interplay between biology and culture, many mammals share one or more building blocks of human rhythmicity. Biological biases amplified by cultural transmission would result in human rhythm as we know it.