All vertebrates, from baboons to crocodiles, exhibit yawning or yawn-like behavior. Despite its ubiquity, the purpose of yawning remains a contentious topic among researchers. Contrary to popular belief, yawning does not increase oxygen in the blood, says Andrew Gallup, a professor in behavioural biology at Johns Hopkins University. The actual reason for yawning is still under investigation, but it’s likely not related to respiration as commonly thought.