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)

A woman dressed up for Halloween travels on a Metro train in São Paulo, Brazil on October 30, 2017. (Photo by Cris Faga/Rex Features/Shutterstock)

People cross Flagstaff Hill as the snow starts to fall, in Schenley Park, on their way to the Carnegie Mellon University campus, Tuesday, March 20, 2018, in the Oakland section of Pittsburgh. Yet another powerful storm bore down on the Northeast on Tuesday, with wind-whipped snow falling in parts of Pennsylvania and New Jersey as people grumbled and complained about a first day of spring that looked an awful lot like the last weeks of winter. (Photo by Darrell Sapp/Pittsburgh Post-Gazette via AP Photo)

A masked Kashmiri protester shouts freedom slogan near burning tires set up as road blockade by protesters in Srinagar, Indian controlled Kashmir, Tuesday, July 19, 2016. The largest street protests in recent years in the disputed region, that left dozens of people dead and hundreds injured erupted more than a week ago after Indian troops killed a popular young rebel leader. (Photo by Dar Yasin/AP Photo)

Bo, a 55-day-old baby Echidna known as a puggle, rests in the hands of vet nurse Annabelle Sehlmeier at Taronga Zoo in Sydney November 1, 2012. The puggle was brought to the zoo after it being found by itself on a walking track north of Sydney and will be fed by hand until it is weaned at about six months of age. (Photo by Tim Wimborne/Reuters)

Kale grows at Kajodlingen farm in Gothenburg, Sweden, September 28, 2016. They are doing it on the rooftops, on tower block balconies and even on a disused railway: Swedes have discovered a passion for urban gardening as a way of growing fresh food and getting back in touch with nature. Part of a global movement, an increasing number of Swedish city-dwellers are growing their own in window boxes and allotments or are visiting public gardens built in or on industrial or office spaces. (Photo by Maxim Shemetov/Reuters)

Mikhail Baburin, 66, talks to his cat Marquis at his house in the remote Siberian village of Mikhailovka, Krasnoyarsk region, Russia, December 5, 2016. Baburin, a former Navy man, barge worker and employee of a military plant in Krasnoyarsk, is the last inhabitant of Mikhailovka, which was founded in the 19th century by migrants from Russia's Mordovia region. He moved in 2000 to Mikhailovka where he was born and has lived there all alone for the last 10 years with only domestic animals. (Photo by Ilya Naymushin/Reuters)

Vehicle lights illuminate a street after a massive blackout, in San Juan, Puerto Rico, Thursday, September 22, 2016. Puerto Ricans faced another night of darkness Thursday as crews slowly restored electricity a day after a fire at a power plant caused the aging utility grid to fail and blacked out the entire island. (Photo by Carlos Giusti/AP Photo)