Babies first laugh around four months of age . It is unclear whether or not they can understand humor at this age. But by five months, they laugh in response to anything absurd.

Silly faces, ridiculous dances, and funny noises – if you're waiting for your baby's first laugh, we bet you've tried it all.

Dr Caspar Addyman is an expert on babies' laughter. Hearing your little laugh is one of the best sounds in the world. But as well as being extremely infectious – did you know that their laughter ...