Revellers enjoy the Notting Hill Carnival for the first time in three years in London, United Kingdom on August 28, 2022. (Photo by Simon Jones/The Sun)
Members of rival teams fight with oranges during an annual carnival battle in the northern Italian town of Ivrea, Italy on February 11, 2018. Established in 1808, the Carnival of Ivrea is one of the oldest and most particular festivals in the world. (Photo by Alessandro Bianchi/Reuters)
Costumed revelers pose in front of the Chapell bridge on the opening day of the carnival in Lucerne, Switzerland, 20 February 2020. The carnival takes place in Lucerne from 20 to 25 February 2020. (Photo by Alexandra Wey/EPA/EFE)
A member of Brazilian samba school “Aguia de Ouro” takes part in a parade at Anhembi sambadrome as part of carnival in Sao Paulo, Brazil, early 25 February 2017. The Sao Paulo Carnival runs from 24 to 28 february 2017. (Photo by Fernando Bizerra Jr./EPA)
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.
Participants in costumes arrive at the Notting Hill Carnival in London, Britain, 29 August 2022. The Notting Hill Carnival is the largest street carnival in Europe and returned to London after two year break due to the coronavirus pandemic with more than a million people expected to attend the two-day celebration of Caribbean heritage on 28 and 29 August. (Photo by Tolga Akmen/EPA/EFE)