Visitors watch a California sea lion at the Smithsonian National Zoological Park on Thursday May 26, 2022 in Washington, DC. (Photo by Matt McClain/The Washington Post)
A picture taken on June 3, 2022 shows a unique albinos Galapagos giant tortoise baby, born on May 1, at the Tropicarium of Servion, western Switzerland. Albinos Galapagos tortoises have never been observed in captivity or in the nature. The Galapagos giant tortoises are strictly protected and are among the most endangered species among CITES-listed animals. (Photo by Fabrice Coffrini/AFP Photo)
A baby goat named Simba, has the World's longest ears which are 48 cm, is seen with her owner in Karachi, Pakistan on June 16, 2022. (Photo by Yousuf Khan/Anadolu Agency via Getty Images)
Peasants celebrate a traditional festival “Corpus Cristhi” since the time of the conquest, in Anolaima in the department of Cundinamarca, Colombia on June 29, 2022. Peasants collect all kinds of fruits and assemble great representative figures in gratitude to God for this festival. (Photo by Yair Suarez/Anadolu Agency via Getty Images)
In this Wednesday, May 23, 2012 photograph, a young deer and a cat share a moment in Feench village near Jodhpur, Rajasthan state, India. (Photo by 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.