Two Inuit children at Point Barrow, Alaska, holding the tusks of a large walrus, probably killed for food, circa 1930. (Photo by General Photographic Agency/Getty Images)

Australian model and designer Madeline Stuart, who has Down syndrome, acknowledges attendees after presenting creations from her label 21 Reasons Why By Madeline Stuart during New York Fashion Week in Manhattan, New York, U.S., February 12, 2017. (Photo by Andrew Kelly/Reuters)

Attendees wear a cardboard “Facebox” at the 2017 South By Southwest (SXSW) Interactive Festival at the Austin Convention Center in Austin, Texas, U.S., on Monday, March 13, 2017. The SXSW Interactive Festival features a variety of tracks that allow attendees to explore what's next in the worlds of entertainment, culture, and technology. (Photo by David Paul Morris/Bloomberg)

A cowgirl participates in the barrel race competition at the Bill Pickett Invitational Rodeo on April 1, 2017 in Memphis, Tennessee. The Bill Pickett Rodeo is the nations only touring black rodeo competition. The rodeo celebrates western heritage and the contributions that black cowboys and cowgirls have made to the sport of rodeo. (Photo by Scott Olson/Getty Images)

A man runs away during a police round up of suspected drug addicts in Kabul, Afghanistan December 27, 2015. Afghan officials have opened a new drug treatment centre in an abandoned NATO military base in Kabul, in the latest attempt to stamp out the country's massive problem of drug abuse. Camp Phoenix, a former training camp on the edges of Kabul set up by the U.S. army in 2003, will take in around 1,000 homeless drug addicts who will receive food, medical attention and treatment, said Public Health Minister Ferozuddin Feroz. (Photo by Ahmad Masood/Reuters)

Pokot men carry a part of a carcass of a bull killed by a young man during an initiation ceremony in Baringo County, Kenya, January 20, 2016. Far from the bustling city of Nairobi, in an isolated corner of Kenya's Rift Valley, young men from the Pokot community spear a bull in a ceremony called Sapana that takes them into adulthood. (Photo by Siegfried Modola/Reuters)

The Aurora Borealis (Northern Lights) lights up the sky near the village of Pallas (Muonio region) of Lapland, Finland September 8, 2017. (Photo by Alexander Kuznetsov/Reuters/All About Lapland)

Open jaws of a Great White Shark Carcharodon Carcharias, South Africa. (Photo by Stephen Frink Collection/Alamy Stock Photo)