Longitudinal tracking of dyadic body temperature synchrony in social pairs across species.

Social behavior shapes efficient vocal communication and broadly impacts our mental health. While social interactions have been suggested to synchronize daily rhythmicity or even brain activity, examining biophysical signals across naturally behaving individuals in a non-intrusive manner remains challenging. Here, we developed a lightweight, miniature wireless thermo-sensor device and implanted it subcutaneously in pairs of mice or zebra finches to track body temperature fluctuations continuously in their home cages. In both species, longitudinal monitoring revealed increased body temperature synchrony between co-housed pairs despite differing social contexts. Notably, Spearman correlation coefficients differed most during huddled sleep phases, being higher in nocturnal mice and lower in diurnal zebra finches when compared to their active social interactions during waking. Our innovative wearable thermo-sensors provide a powerful new tool for further investigating underlying brain mechanisms when combined with simultaneous monitoring of neuronal activity to inspire translatable biomarkers for clinical targets and improved methods for efficient social learning.