Participants wearing masks during a hazy day at the Beijing International Marathon in front of Tiananmen Square, in Beijing, October 19, 2014. (Photo by Reuters/Stringer)

A red squirrel sniffs out nuts inside Christmas stockings as part of the festive celebrations and enrichment programme at Wildwood Escot Park in Ottery St Mary, Devon, United Kingdom on December 17, 2020. (Photo by Ben Birchall/PA Images via Getty Images)

A family takes a picture at the Oscar Myer Wienermobile during a visit to “The Flower Fields”, as California opens up from the pandemic, in Carlsbad, California, U.S., March 31, 2021. (Photo by Mike Blake/Reuters)

Belgian-British teenager Zara Rutherford closes the canopy of her Shark Ultralight airplane as she prepares to take off at the Kortrijk-Wevelgem airfield in Wevelgem, Belgium, Wednesday, August 18, 2021. A Belgian-British teenager took to the skies Wednesday in her quest to become the youngest woman to fly around the world solo. Nineteen-year-old Zara Rutherford took off from an airstrip in Wevelgem, Belgium, in an ultralight plane looking to break the record set by American aviator Shaesta Waiz, who set the world benchmark at age 30 in 2017. (Photo by Virginia Mayo/AP Photo)

A man walks pat sculptures with face masks on along an alley in Beijing on August 3, 2021. (Photo by Noel Celis/AFP Photo)

A model stumbles as she presents a creation by Swiss designer Albert Kriemler as part of his Spring/Summer 2020 women's ready-to-wear collection show for fashion house Akris during the Paris Fashion Week in Paris, France, September 29, 2019. (Photo by Gonzalo Fuentes/Reuters)

Revellers perform during the “Salsodromo”, the kick-off of the music and cultural festival Feria de Cali (Cali Fair) in Cali, Colombia, on December 25, 2021. The “Salsodromo”, an event in which more than 2,500 revellers and salsa music dancers perform along a kilometre-long stripe, marks the start of the Feria de Cali festival every year. (Photo by Paola Mafla/AFP Photo)

The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)