Alladi Ramakrishnan Hall

The prenatal origins of vocalizations in marmoset monkeys

Darshana Narayanan

Developmental Neuromechanics and Communication Lab, Princeton University, Princeton, NJ, USA

In primates a number of vocal behaviors are present at birth. Human and non-human primates can cry as soon as they are born. In addition to cries, non-human primates produce a number of adult-like vocal signals. How these behaviors develop, remains a mystery. Using dense sampling, ultrasound imaging on awake, pregnant marmoset monkeys, and a dynamic systems approach to quantify and characterize fetal orofacial development, we show that orofacial movements necessary for producing vocalizations differentiate from a larger movement pattern that includes the head region. We also show that signature features of marmoset infant calls emerge prenatally as distinct patterns of orofacial movements. Our results establish that aspects of vocal behavior in marmosets have a period of prenatal development. Although some researchers have used simulated environments and computational models to study the human fetus as a coupled brain-body-environment system, no experimental work on primates has been presented to date. Here, we fill the gap, and highlight general principles of early development. Our work can be used to make predictions regarding how perturbations in the fetal stage can alter the trajectory of vocal development. It can also be used to inform the growing field of developmental robotics.