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)

Ellen MacRae a student from Edinburgh University take a lateral flow antigen test at a test centre which is also open to students in Edinburgh Napier University, Queen Margaret University and SRUC on December 1, 2020 in Edinburgh, Scotland. The programme is running in partnership between the University of Edinburgh and other Scottish universities, the Scottish Government and NHS Test and Protect, supporting students leaving their term-time accommodation to travel home at the end of term for the winter break. (Photo by Jeff J. Mitchell/Getty Images)

Two men look at the sea while taking part in the annual New Year's dive into the North Sea in Scheveningen, Netherlands on January 1, 2020. (Photo by Piroschka van de Wouw/Reuters)

A reveller wears a carnival mask in St. Mark's Square to celebrate Venice's annual colourful carnival, which has been cancelled this year due to the coronavirus disease (COVID-19) pandemic, in Venice, Italy, February 7, 2021. (Photo by Manuel Silvestri/Reuters)

Viking re-enactors representing the rival armies of the Vikings and Anglo-Saxons skirmish near Clifford’s Tower during the Jorvik Viking Festival on February 23, 2019 in York, England. The annual Jorvik Viking Festival held in York is recognised as the largest event of its kind in Europe. This year the festival remembers the role that the Viking women played during those turbulent times. (Photo by Christopher Thomond/The Guardian)

A dancer poses for her own photographer in front of pink cherry tree blossoms during a sunny spring morning at the Parc de Sceaux gardens near Paris, France, April 12, 2019. (Photo by Christian Hartmann/Reuters)

A first white-handed gibbon infant born at the Skopje Zoo is seen with his mother in Skopje, North Macedonia on May 9, 2019. (Photo by Ognen Teofilovski/Reuters)

An Indian Sadhu, or Hindu holy man, performs a yoga position on International Yoga Day at Kamakhya temple in Gauhati, India, Friday, June 21, 2019. (Photo by Anupam Nath/AP Photo)