Koko the rhyming gorilla and the woman trying to get her pregnant

She tells jokes, talks in rhyme and is pals with DiCaprio - but there's one thing missing from Koko's life: a baby. A riveting new documentary explores the controversial bond between one woman and her ape

It wasn't the first time I had looked into the eyes of a gorilla, but it was the first time a gorilla had asked me to sit down so she could check out my nail varnish.

Koko is a 44-year-old Western Lowland gorilla who communicates in sign language. I was in California to make a documentary about her life and, uniquely, Koko had to give final signoff for the film to go ahead. Despite the appalling state of my nails, she agreed.