Contagious Yawning and Seasonal Climate Variation

Andrew C Gallup,Omar Tonsi Eldakar

doi:10.3389/fnevo.2011.00003

Andrew C Gallup, Omar Tonsi Eldakar

Open Access

https://doi.org/10.3389/fnevo.2011.00003

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Abstract

Recent evidence suggests that yawning is a thermoregulatory behavior. To explore this possibility further, the frequency of contagious yawning in humans was measured while outdoors in a desert climate in the United States during two distinct temperature ranges and seasons (winter: 22°C; early summer: 37°C). As predicted, the proportion of pedestrians who yawned in response to seeing pictures of people yawning differed significantly between the two conditions (winter: 45%; summer: 24%). Across conditions yawning occurred at lower ambient temperatures, and the tendency to yawn during each season was associated with the length of time spent outside prior to being tested. Participants were more likely to yawn in the milder climate after spending long periods of time outside, while prolonged exposure to ambient temperatures at or above body temperature was associated with reduced yawning. This is the first report to show that the incidence of yawning in humans is associated with seasonal climate variation, further demonstrating that yawn-induced contagion effects can be mediated by factors unrelated to individual social characteristics or cognitive development.

Highlights

Numerous hypotheses have been proposed to explain why vertebrates yawn, and the two prevailing hypotheses favor either physiological or social function (Guggisberg et al, 2010)
Physiological hypotheses predict that yawning acts to aid in the regulation of a given body state, while the social hypothesis predicts that yawning functions to synchronize group behavior by communicating unpleasant mental and physical states
Recent evidence for this model comes from prelimbic brain temperature recordings in rats (Rattus norvegicus), showing that yawning is preceded by rapid increases in brain temperature and followed by corresponding decreases in brain temperature (ShoupKnox et al, 2010)

Summary

Introduction

Numerous hypotheses have been proposed to explain why vertebrates yawn, and the two prevailing hypotheses favor either physiological or social function (Guggisberg et al, 2010). One of the physiological hypotheses receiving growing support proposes a role of yawning in brain thermoregulation (Gallup and Gallup, 2007, 2008) Recent evidence for this model comes from prelimbic brain temperature recordings in rats (Rattus norvegicus), showing that yawning is preceded by rapid increases in brain temperature and followed by corresponding decreases in brain temperature (ShoupKnox et al, 2010). According to this model, cooling is primarily the result of enhanced cerebral blood flow and countercurrent heat exchange with ambient air. Yawns become more frequent during initial increases in ambient temperature, but decrease as temperatures approach body temperature

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