A model poses for a photographer backstage ahead of the Ferreira Couture catwalk show at Malta Fashion Week in Valletta, Malta on July 20, 2022. (Photo by Darrin Zammit Lupi/Reuters)
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.
A spectator cools herself at a water spraying fan at the Australian Open tennis championships in Melbourne, Australia, Tuesday, January 17, 2017. (Photo by Kin Cheung/AP Photo)
Five-month-old baby elephant Fah Jam swims during a hydrotherapy treatment as part of a lengthy rehabilitation process to heal her injured front left foot at a rehabilitation center in Pattaya, Thailand January 5, 2017. The baby elephant was injured at three months old when she got stuck in an animal snare put up by villagers to prevent elephant intrusions in Chanthaburi province. (Photo by Athit Perawongmetha/Reuters)
A model displays a creation during the Sophia Webster presentation at London Fashion Week, in London, Britain February 19, 2018. (Photo by Paul Hackett/Reuters)
A United States Border Patrol agent on horseback tries to stop a Haitian migrant from entering an encampment on the banks of the Rio Grande near the Acuna Del Rio International Bridge in Del Rio, Texas on September 19, 2021. The United States said Saturday it would ramp up deportation flights for thousands of migrants who flooded into the Texas border city of Del Rio, as authorities scramble to alleviate a burgeoning crisis for President Joe Biden's administration. (Photo by Paul Ratje/AFP Photo)
Chinese workers maintain an Animatronic Dinosaurs at Gengu Dinosaurs Science and Technology company on November 13, 2019 in Zigong, Sichuan Province, China. There are hundreds of simulated dinosaur manufacturers in Zigong City. It is the largest simulated dinosaur manufacturing in China. It accounts for 95% of mainland China's production and 85% of the world's total. Its products are exported to more than 100 countries. (Photo by Lintao Zhang/Getty Images)
Cast member, Iranian actress Zar Amir-Ebrahimi poses during a photocall for the film “Holy Spider” at the 75th edition of the Cannes Film Festival in Cannes, southern France, on May 23, 2022. (Photo by Stephane Mahe/Reuters)