A tree is silhouetted against a light display during the The Magical Lantern Festival marking the Chinese new year at Chiswick House in London, Britain January 18, 2017. (Photo by Neil Hall/Reuters)
A guest poses against a video installation displayed at the Moncler catwalk show during Milan Fashion Week Spring 2019 in Milan, Italy, September 19, 2018. (Photo by Stefano Rellandini/Reuters)
Pakistan girls make selfies holding a Pakistan-made weapon displayed at the four-day International Defence Exhibition and Seminar (IDEAS) 2016 in Karachi, Pakistan, Wednesday, November 23, 2016. (Photo by Shakil Adil/AP Photo)
Guns decorated with gold and jewellery are displayed in the Drugs Museum, used by the military to showcase to soldiers the lifestyles of Mexican drug lords, at the headquarters of the Ministry of Defense in Mexico City, October 14, 2016. (Photo by Henry Romero/Reuters)
A view of fluffy toy bears displayed for attraction outside the windows of a hotel in Yantai in Shandong province Thursday, January 6, 2022. (Photo by Tang Ke/Future Publishing via Getty Images)
People look at “The Fall” sculpture by Steve Cramb on display between Bondi and Tamarama beach as part of the Sculpture by the Sea exhibition in Sydney on October 21, 2022. (Photo by Muhammad Farooq/AFP Photo)
A woman poses for a souvenir photo with a cat statue on display at the Shenzhen Bay commercial district, in Shenzhen, China's Guangdong province, Monday, September 15, 2025. (Photo by Andy Wong/AP Photo)
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.