IT was an ordinary day at the Smithsonian National Zoo in Washington DC. Five orang utans were milling about the yard of the exhibit called the think tank, playing intermittently with a barrel that a keeper had rolled out for them. By the time staff had realised that the power to the electric fence on top of the wall had failed, orang utan Bonnie had up-ended the barrel, scaled it and escaped. Mingling with the zoo’s visitors, her baby son Kiko clinging to her body, she headed for lunch…

This article first appeared in the Guardian on 19 June 2003. To continue reading click here.