In this November 28, 1966 file photo, one of the 10 beagles involved in the first test of the Veterans Administration Hospital in East Orange, N.J. smokes a cigarette through a machine linked to its windpipe by a plastic tube to test any link between smoking and emphysema. (Photo by AP Photo)

In this photo taken Tuesday, April 14, 2015, immigrant men armed with machetes make their way onto a Durban, South Africa, street during clashes with police and in search of locals that attacked foreign shop owners in the city center. (Photo by Tebogo Letsie/AP Photo)

Local residents take part in the celebrations of Kolyada pagan holiday, which over the centuries has merged with Orthodox Christmas festivities and marks the upcoming end of winter, in the village of Noviny, Belarus, January 21, 2017. (Photo by Vasily Fedosenko/Reuters)

Fifty years ago, as France exploded in mass protests, words scrawled on the walls of the Sorbonne summed up the revolutionary zeal of the time: “Run free, comrade, we’ve left the old world behind!”. Sexual liberation, artistic creativity and anti-capitalism were the order of the day. For those who were there, it was an unforgettable time. Here: A wounded student is transported by first-aid workers during riots on the Boulevard Saint-Michel, Paris, France on May 6, 1968. (Photo by Gökşin Sipahioğlu/SIPA Press)

Emma Raducanu of Great Britain takes a selfie after victory over Stephanie Voegele of Switzerland in the first round of the women's singles of the US Open at the USTA Billie Jean King National Tennis Center on August 31, 2021 in New York City. (Photo by Rex Features/Shutterstock)

Battersea Power Station Ice Rink in London, United Kingdom on November 13, 2022. Running until 8th Jan. 2023, a large outdoor ice-rink outside the power station and next to the riverside brings in festive Christmas fun with vivid illumination. (Photo by Guy Corbishley/Alamy Live News)

A person watches Mount Etna, Europe's most active volcano, light up the night sky with eruptions, as seen from Piazzale Funivia dell'Etna, Italy on December 1, 2023. (Photo by Etna Walk/Giuseppe Distefano/Handout via Reuters)

In this picture taken on January 11, 2021, young gymnasts train at the Li Xiaoshuang Gymnastics School in Xiantao, Hubei province. This summer's delayed Tokyo Olympics, which are now due to start on July 23, 2021, will be the defining moment for Chinese gymnasts who have trained relentlessly since as young as age four in the pursuit of gold. (Photo by Nicolas Asfouri/AFP Photo)