A group of children and their dog playing an Easter game in Cardiff. The game involves trying to eat an Easter egg off a piece of string without using their hands. (Photo by Richards/Fox Photos/Getty Images). 26th March 1937

From the waters edge a New York policeman urges two young children to put their bathing costumes back on. (Photo by Ed Clarity/Keystone/Getty Images). July 1949

Yoga Studio for ultra-Orthodox located at Ramat Beit Shemesh Nachal zohar 4/8, Israel. Separate classes for men, women and children. Occupations look quite funny... (Photo by Michal Fattal)

Two children jumping through a water hydrant's shower on a New York street. They have come from a neighbouring co-educational playgroup organised by the city's Police Department. (Photo by Orlando/Getty Images). 1950

Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)

Myanmar punks walk in the downtown area as they take part in a punk gathering ahead of the Thingyan water festival in Yangon, Myanmar, 12 April 2017. Myanmar punks have been gathering in Yangon on the day ahead of Thingyan water festival to celebrate every year. The annual water festival is marked with large groups of people congregating to celebrate by splashing water and throwing powder at each others faces as a symbolic sign of cleansing and washing away the sins from the old year to mark the traditional New Year in countries such as Myanmar, Thailand, Laos and Cambodia. This year, the Myanmar Thingyan water festival falls on 13 April and ends on 16 April. (Photo by Lynn Bo Bo/EPA)

Clinging on with sticky toes, a green tree frog sits bravely on its unlikely friend – a large tree python. Curled around the branches of a small coconut tree, the snake appears relatively undisturbed by the bold passenger that has clambered onto its skin. Grown in captivity together, the pair display no signs of aggression or fear, comfortable with their encounters high up in the leafy branches. Photo enthusiast Fahmi Bhs watched in surprise as the frog slowly climbed along the scales of the metre long snake in a zoo in Jakarta, Indonesia. (Photo by Fahmi Bhs/Solent News/SIPA Press)