People in colorful costumes perform acrobatics for drivers waiting at red lights in Nairobi, Kenya on February 20, 2024. (Photo by Gerald Anderson/Anadolu via Getty Images)
Adventurer Sam Cossman movies towards the huge lava lake wearing a custom built industrial proximity heat suit on December 20, 2014 in Ambrym, Vanuatu. (Photo by Conor Toumarkine/Barcroft Media)
A man hugs a child at the Santuario de Nuestra Senora de Guadalupe during a celebration on the Virgin of Guadalupe Day in Guatemala City, December 12, 2015. According to Catholic believers, December 12 marks the anniversary of the apparition of the Virgin of Guadalupe at the Cerro del Tepeyac in Mexico. (Photo by Jorge Dan Lopez/Reuters)
Mortuary Chamber of the Ponte San Pietro Hospital in the Province of Bergamo on March 18, 2020 – the area in Italy where the highest number of infections was recorded by COVID19 Coronavirus. (Photo by Carlo Cozzoli/IPA/SIPA Press/Rex Features/Shutterstock)
Tasmanian devils play on May 31, 2023 in Sydney, Australia. Creatures living at the zoo welcomed the arrival of winter with snow and an array of treats. Many of the zoo's species would naturally experience seasonal changes within their wild ranges. With the support of the SEA LIFE Sydney Aquarium's sub-Antarctic penguin team, snow is predicted to hit the Darling Harbour-based attraction on Wednesday morning. (Photo by Jenny Evans/Getty Images)
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.
Drinkers celebrated on the last Friday before Christmas in York, United Kingdom on December 18, 2020. Black Eye Friday, affectionately named for its tendency to prompt drink-fuelled punch ups as the Christmas cheer spills over, has been dampened this year by the global coronavirus pandemic shutting bars and banning socialising. (Photo by Nb press ltd)