Happy was one of seven Asian elephant calves captured, probably from the same herd, in Thailand in the early 1970s. Named after Disney’s seven dwarves, they were shipped to America and sold to circuses and zoos. Happy and Grumpy ended up in the Bronx zoo, where they lived in an enclosure for 25 years. In 2002 they were transferred to a larger enclosure with a second pair of pachyderms, Patty and Maxine. Their new environment was a little closer to the wild one, in which elephants form large families. But Patty and Maxine charged at Grumpy, injuring her. Unable to walk and with suppurating wounds, Grumpy was euthanised.

Happy was then paired with a younger female elephant, Sammy. She died of kidney failure in 2006. But meanwhile Happy had become a scientific celebrity. In 2005 she became the first elephant to pass the “mirror self-recognition test”, an indicator of self-consciousness. Scientists painted a white cross over her left eye, and led her to a large mirror. Happy repeatedly touched the marking with her trunk, showing that she recognised herself. Most animals (and human infants) cannot do this.