It has long been known that yawns are contagious, but human beings have long since evolved defense mechanisms to keep excessive yawning at bay.

However, animal yawns–while not normally transmissible to humans–have been known to cross over in a process known as zoonosis. This was most recently demonstrated in the so-called “BY20” yawning pandemic. After a birder observed a small passerine yawning, they caught that yawn and transmitted it to their friends and family. With no natural defenses, the affected people yawned until they passed out from an abundance of oxygen to their brains.

Despite quarantine attempts, the BY20 bird yawning spread worldwide, accelerated by international travel and a slow news cycle. Within 48 hours, cases were active on seven continents.

  • Like what you see? Purchase a print or ebook version!