A gibbon at a Leicestershire zoo has reached the age of 50 due to its "chilled-out" persona, keepers believe.
The lar gibbon known as "Granny" Jane was aged as four by vets on her arrival from the wild to Twycross Zoo in 1966.
Staff at the zoo said the apes rarely reach such an age in the wild due to disease and infection.
Keepers have described Jane as "chilled-out and wise", but she is also "often stubborn".
Natalie Gudger, from Twycross Zoo, said: "Jane is looked after well, has a good diet, she is monitored closely and lives in a safe environment."
Jane has had 13 offspring over the years and has descendants at six different European zoos.
Deputy Curator, Julian Chapman, said: "Normally captive gibbons live until their late 30s, early 40s, so she's doing very well.
"Jane can be seen swinging around her enclosure within our primate house, and she's surprisingly agile for her age."
The lar gibbon are listed as critically endangered on the International Union for Conservation of Nature Red List.