Everyone's ear preserves its structure as you get older

Professor Mark Nixon of University of Southampton told BBC World Service's Outlook programme that ears do not change much as we get older, unlike other body parts.

This, he believes, means they are well suited for identification purposes, giving them a "unique advantage" in terms of age and expression.

"If you compare it with faces, the advantage of these is that they're both non-invasive biometrics - you don't have to make contact. But the disadvantage with faces is that they smile, they get old, you get wrinkles," he said.

"Your ear just carries on growing and it preserves its structure as you get older.

"That makes it quite advantageous in terms of biometrics."

Ear pattern

Biometric signatures are typically taken from teeth, fingerprints and the retina in our eyes.

Various governments have been looking into using them for systems such as ID cards and passports.

Biometrics have also already been put to use in areas such as computing, where a fingerprint can be taken to register a user.

Face recognition is already running but can have problems

And biometric facial recognition has already become a reality, with one police force describing it as the biggest forensic breakthrough since DNA.

But the problems of people's faces changing prompted Dr Nixon to look into using the ear as an alternative.

He pointed out that, for example, people do not tend to "decorate" their ear, as opposed to their face, with things such as make-up.

Two years ago the Canadian Passport Office ordered that smiling was banned from passport photos, as was wearing hairpieces that "substantially" altered a person's appearance.

"The problem with ears is obviously that you have hair, and sometimes the hair can obscure it, but with imaging technology we should be able to solve that," added Prof Nixon.