A migrant smokes a cigarette as he waits among others to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. Thousands of migrants clamoured to enter European Union member Croatia from Serbia on Monday after a night spent in the cold and mud of no-man's land, their passage west slowed by a Slovenian effort to impose limits on the flow to western Europe. (Photo by Marko Djurica/Reuters)

A newborn grey seal pup is tended by its mother at Donna Nook, a nature reserve on the county’s coastline managed by Lincolnshire Wildlife Trust in Lincolnshire, UK on November 23, 2015. (Photo by David Tipling/Rex Shutterstock)

People walk along a street with long-tailed macaques in Lopburi, north of Bangkok November 29, 2015. (Photo by Jorge Silva/Reuters)

In this Wednesday, December 2, 2015 photo, Dr. Gal Kelmer, head of the department of large animals, unties a horse after its operation at the University's Koret School of Veterinary Medicine in Rishon Lezion, Israel. “Horses have an instinctive response of flight from danger”, Kelmer said. “The minute they wake up they start trying to stand and run, even if they don't have control of their limbs. So then they fall”. (Photo by Oded Balilty/AP Photo)

Valery Bystritskii, 10, gets a fellow student into a lock at Bunny's Gym in July 2015 in Winchester, Tennessee. (Photo by Mike Saliba/Barcroft USA)

A cat dressed in a traditional Ukrainian embroidered shirt takes part in a parade in Kiev, Ukraine on May 28, 2016. (Photo by Gleb Garanich/Reuters)

Somali couple Mohamed Noor (L) and Huda Omar pose for a photograph at their makeshift home during their wedding ceremony in Mogadishu's Rajo camp, Somalia August 17, 2016. Having met two years ago, the pair have just married at Rajo camp, where some 400 families live. Most, like Noor's parents, came here in the early 1990s to flee famine. (Photo by Feisal Omar/Reuters)

China has recently relaxed its one child policy that was used to control a burgeoning population. A couple has their wedding photo taken in an old quarter of Beijing on May 24, 2016. (Photo by Michael Robinson Chavez/The Washington Post)