The human aerodigestive tract and gastroesophageal reflux: an evolutionary perspective

In order to appreciate fully the nature of supraesophageal complications of gastroesophageal reflux in humans, it is essential to view the problem within an evolutionary framework. Examination of the aerodigestive tract anatomy of our mammalian relatives shows that this region in humans is highly derived as compared to other mammals. Among the specializations that adult humans exhibit is a caudal position of the larynx, which results in a permanently expanded oropharynx. These anatomical features underlie our distinctive breathing and swallowing patterns and provide the substrate that allows for the production of articulate speech. While the selection factors that have shaped human evolution obviously favored our derived aerodigestive tract, aspects of this anatomy appear particularly unsuited to accommodate gastroesophageal reflux. Indeed, our unique aerodigestive tract morphology may predispose us to an array of supraesophageal complications of gastroesophageal reflux.