This is Mama, a 59 year-old chimpanzee who was matriarch of the colony at the Royal Burgers Zoo in Arnhem, the Netherlands She was coming to the end of her life, sick and unable to eat ...

The couple later claimed that the chimp, which they named Viki, had learned simple words like 'mama', 'cup' and 'up'. However, very little direct evidence from these early trials survived and due ...