Watch the extraordinary moment when Sir David Attenborough and BBC filmmakers recorded monkeys lying to fellow members of their troop.

Even better, you can watch a further 1,000 more memorable moments, for free, anytime, on your smartphone or tablet, via Attenborough's Story of Life app, which is now available to download via Google Play, or Apple's app store.

Find out more at http://www.bbc.com/earth/storyoflife.

The Story of Life has been produced in collaboration with Sir David Attenborough, BBC Earth and ideas and innovation company AKQA.