From beat to syntax: evolutionary and developmental paths of a shared neural resource for hierarchical processing in music and language

Children who track a musical beat well tend to have stronger grammatical skills, and brief exposure to a regular rhythm can transiently improve grammatical processing. These findings raise the possibility of a shared underlying mechanism, and with it two questions: where did the link come from, and when does it emerge in development? Our central hypothesis is that beat perception, the extraction and prediction of a metrical pulse, and hierarchical syntactic structure building draw on a common computational principle, predictive neural entrainment: the alignment of cortical activity to rhythmic input in a way that enables temporal anticipation. Comparative work indicates that non-human primates track regular input but show little evidence of beat-based prediction. We propose that during hominin evolution the expanding prefrontal cortex exerted stronger top-down control over the auditory-motor pathway, extending an ancestral timing system to meet the hierarchical demands of syntax. For development, we distinguish capacities present in infancy, including beat sensitivity and temporal prediction, from the later coupling of beat-based prediction to syntax, which we hypothesize depends on fronto-temporal maturation; when that coupling emerges is an empirical question. We integrate neuroimaging, comparative, developmental, and clinical evidence into a three-layer model: temporal encoding, structural grouping, and hierarchical prediction, each tied to a distinct neural signature. The model offers an account of why regular rhythmic primes facilitate grammatical processing and why that effect is fragile, why musical experience transfers to speech, and why early insult can leave regularity extraction intact while productive language lags. We separate empirical findings from inferences and state five falsifiable predictions, spanning cross-species comparison, longitudinal development, clinical populations, intervention, and selective musical deficits.