A tourist takes photos in an open-air studio with a view of the Bosphorus in Istanbul, Turkey, Saturday, July 19, 2025. (Photo by Emrah Gurel/AP Photo)
Actress Nina Dobrev kicks off the first-ever Aperolidays celebration with an Aperol Spritz in hand in the second decade of November 2025. (Photo by Aperol)
In animals, yawning can serve as a warning signal. For example, Charles Darwin, in his book The Expression of the Emotions in Man and Animals, mentioned that baboons yawn to threaten their enemies, possibly by displaying large canine teeth. Similarly, Siamese fighting fish yawn only when they see a conspecific (same species) or their own mirror-image, and their yawn often accompanies aggressive attack. Guinea pigs also yawn in a display of dominance or anger, displaying their impressive incisor teeth. This is often accompanied by teeth chattering, purring and scent marking.