What causes BO smell in armpits?

If you're a teenager or have older brothers and sisters, you'll know that one of the bad bits about getting older is you start to get a bit smellier.

Well now scientists have identified the key reason behind smelling bad is an enzyme that causes body odour - often just called 'BO'.

Researches at the University of York and scientists at hygiene product company Unilever discovered a unique 'BO enzyme' found within specific bacteria in the armpits.

The enzyme in the bacteria is responsible for the unique smell of BO.

Dr Michelle Rudden from the University of York's Department of Biology said: "Solving the structure of this 'BO enzyme' has allowed us to pinpoint the molecular step inside certain bacteria that makes the odour molecules."

"This is a key advancement in understanding how body odour works," she said.

Scientists say their research suggests body odour played a big part in the evolution of humans and was used as communication before language was used

Researchers also say that their findings suggest that early humans were smelly too and the smell was an important way of communication during prehistoric times when primitive humans used very little language.