Date of Award

Summer 6-30-2021

Degree Type


Degree Name

Master of Science in Integrative Biology (MSIB)



Major Professor

Dr. Jared Taglialatela

First Committee Member

Dr. Anton Bryantsev

Second Committee Member

Dr. Lisa Ganser

Third Committee Member

Dr. Bill Ensign


Except for humans, extant great apes have evolutionarily conserved lateral ventricular air sacs extending from laryngeal saccules. Humans are the only species of Hominidae that lack this anatomical feature attached to the primary vocal apparatus. As we are the only species that produces spoken language, this association has led to the hypothesis that the loss of lateral ventricular air sacs was necessary for the evolution of spoken language. However, why these sacs are conserved in all other hominids remains unclear. Computer modeling has indicated that air sacs may increase resonance properties, but there are no data from great apes indicating if vocalizations include the use of air sacs during their production. For this study, we hypothesized that we could use high-frame-rate digital audio/video recordings to determine when bonobos (Pan paniscus) inflate their laryngeal air sacs. We identified a region of interest in the air sac area and quantified it using frame-by frame image analysis. We then compared the difference in areas between resting, swallowing, and vocalizing apes. Results suggest air sac inflation may be associated with vocal production but not with other states. The method outlined in this thesis may be utilized in a variety of settings, enabling data collection to test hypotheses regarding the putative function of laryngeal air sacs in extant great apes. Enhancing our understanding of the conservation of laryngeal air sacs in non-human great apes will strengthen hypotheses related to the loss of these sacs in humans and its relevance for the evolutionary origin of language.