These two young siblings appear to cling on to a tree for dear life and even hold hands as they learn the ropes of climbing, on June 25, 2013. (Photo by Tim Fitzharris/Minden/Solent)

In this handout image provided by Ogilvy, a burger made from cultured beef, which has been developed by Professor Mark Post of Maastricht University in the Netherlands (pictured) is shown to the media during a press conference on August 5, 2013 in London, England. The in-vitro burger, cultured from cattle stem cells, the first example of what its creator says could provide an answer to global food shortages and help combat climate change, was fried in a pan and tasted by two volunteers. The burger is the result of years of research by Dutch scientist Mark Post, a vascular biologist at the University of Maastricht, who is working to show how meat grown in petri dishes might one day be a true alternative to meat from livestock.The meat in the burger has been made by knitting together around 20,000 strands of protein that has been cultured from cattle stem cells in Post's lab. (Photo by David Parry)

Hundreds of Nigerians celebrate at an intersection in the flashpoint northern city of Kaduna on March 31, 2015 the victory of main opposition All Progressives Congress (APC) presidential candidate Mohammadu Buhari. (Photo by Nichole Sobecki/AFP Photo)

In this photo released by Xhinhua News Agency, a rescuer evacuates residents near the site of a chemical plant blast in Zhangzhou, southeast China's Fujian Province Tuesday, April 7, 2015. Six people have been hospitalized and hundreds of firefighters deployed to battle a blaze sparked by an explosion at Goure PX Plant that produces the toxic chemical paraxylene, officials said Tuesday. (Photo by Wei Peiquan/AP Photo/Xinhua)

A visitor holds up her toy bunny to the aquarium glass in front of Aurora the Russian polar bear at the Sao Paulo Aquarium in Sao Paulo, Brazil, Thursday, April 16, 2015. (Photo by Andre Penner/AP Photo)

A woman counts her money as she sells flowers ahead of International Women's Day in central Kiev, Ukraine on March 7, 2019. (Photo by Gleb Garanich/Reuters)

A protester raises her fist at the entrance of Highway 280 and S. 4th St. as people protest the killing of George Floyd in Minneapolis in downtown San Jose, Calif., on Friday, May 29, 2020. (Photo by Nhat V. Meyer/Bay Area News Group)

China Airlines stewardess Wang Wen Hwang leaps from the burning China Airlines plane after assisting the passengers to safety February 27, 1980. Miss Wang saved most of the lives of the passengers despite her injuries. She was the last to leave the planes. (Photo by AP Photo)