Defining the most 'normal' shape of a human skull
22 November 2013 Last updated at 10:03 GMT
Reconstructive surgery for people born with a misshapen skull is one of medicine's most complicated challenges.
Part of the problem for surgeons is defining what a normal head actually looks like.
A team of Liverpool-based surgeons, and artists, have been hoping to find the answer.
Tim Muffett reports.