Women wipe the sweat from their faces as they wait for bus on a hot and humid summer day in Mumbai, India, Thursday, May 23, 2024. (Photo by Rafiq Maqbool/AP Photo)
A caiman swims amidst trash in Canal das Taxas at the Recreio dos Bandeirantes neighborhood in west Rio de Janeiro, Brazil, on November 22, 2023. The urban expansion of the area and the resulting pollution have put the yacare caiman (Caiman latirostris) “in danger of extinction”. (Photo by Tercio Teixeira/AFP Photo)
Women atop a boat take a group photo as the U.S. Navy’s Flight Demonstration Squadron’s Blue Angels perform in the skies over Annapolis, Maryland, on May 22, 2024. (Photo by Kevin Lamarque/Reuters)
A man falls from his motorcycle after hitting a water buffalo on his way to work outside Phnom Penh, Cambodia, Friday, September 6, 2024. Cambodian animal owners have been warned to keep their animals, which often cause traffic accidents, leashed and could face prison time if relatives of those who die or are injured in such accidents initiate legal proceedings. (Photo by Heng Sinith/AP Photo)
A tree frog uses a leaf as an umbrella in pouring rain in Karacabey floodplain near the city of Bursa, Turkey in the first decade of June 2023. (Photo by Savas Sener/Solent News & Photo Agency)
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 Chinese girl touches the gun of a relievo featuring Chinese soldiers fighting with Japanese troops during World War II at an exhibition at the Anti-Japan War Museum to mark the 60th Anniversary of the Victory of the Chinese People's War of Resistance Against Japan on August 18, 2005 in Beijing, China. (Photo by Cancan Chu/Getty Images)
Over 30 Douglas C-47 Skytrains (Dakotas) making final preparations for flight formation practice before the 75th D-Day Anniversary flight to Normandy in Duxford, England on June 4, 2019. (Photo by UK Air Force Images)