Distinct developmental trajectories of autonomous behaviors and agency in rodents.

Behavioral interactions within the nuclear family may play a pivotal role in the emergence of autonomy and agency in mammals. While the emergence of a behavior may arise over weeks in line with nervous system maturation, individual events occur on sub-second time scales. This makes it uniquely challenging to track development in the lab where observations are made over minutes to hours or in ecological studies which lack individual specificity and sub-second precision. Here we study families of gerbils, a highly social rodent, raised in enlarged home-cage environments over weeks of development, using continuous video recordings to capture tens of millions of time points per family. Focusing on postnatal day 15 (when pups leave the nest) to day 30 (around the time when pups would disperse) we identify distinct developmental trajectories for both autonomous behaviors (exploration, food and water foraging), and social behaviors (huddling, approach, time spent together). Most of these behaviors emerge in concert with clear diurnal and crepuscular patterns and we find sex differences in both autonomous and social behaviors. Our work supports the emergence of distinct autonomous and social behavior phenotypes as the behavioral correlates of critical developmental periods of maturation of the rodent brain and can form the basis of future research on development from both neuroscience and behavioral biology perspectives.