title: Yawn duration predicts brain weight and cortical neuron number in mammals.
abstract: Research indicates that the motor action pattern of yawning functions to promote cortical arousal and state change through enhanced intracranial circulation and brain cooling. Because the magnitude of this response likely corresponds to the degree of neurophysiological change, we hypothesized that interspecies variation in yawn duration would correlate with underlying neurological differences. Using openly accessible data, we show that both the mean and variance in yawn duration are robust predictors of mammalian brain weight and cortical neuron number (ρ-values > 0.9). Consistent with these effects, primates tend to have longer and more variable yawn durations compared with other mammals. Although yawning has long been considered a stereotyped action pattern, these findings reveal substantial variation in this response and highlight the importance of measuring yawn duration in future research.
authors.affiliation: Department of Psychology, State University of New York at Oneonta, Oneonta, NY 13820, USA a.c.gallup@gmail.com.
authors.forename: Andrew C
authors.identifier: 0000-0002-0512-5238
authors.initials: AC
authors.lastname: Gallup
authors.affiliation: Department of Psychology, State University of New York at Oneonta, Oneonta, NY 13820, USA.
authors.forename: Allyson M
authors.initials: AM
authors.lastname: Church
authors.affiliation: Department of Psychology, State University of New York at Oneonta, Oneonta, NY 13820, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Pelegrino
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000166:cytology; D002452:Cell Count; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000166:cytology; D008322:Mammals / Q000502:physiology*; D009474:Neurons / Q000166:cytology*; D009929:Organ Size; D015000:Yawning / Q000502:physiology*
keywords: brain scaling; cognition; cortical arousal; neuron number; primates; yawning