How our bodies have changed over time. This week: The vanishing arm muscle
PUT your arm on the table palm face up. Touch your thumb to your little finger and flex your wrist. Can you see a band rising in your wrist? If so, you are one of the 80 per cent or so of the population who still has the palmaris longus muscle, which runs from the arm to the wrist. Don’t fret if you don’t have it, as it has no obvious purpose: it’s thought to have become largely redundant since humans developed opposable thumbs. In fact, surgeons often graft this muscle elsewhere in the body following disease or trauma.
Quite why some people still have the muscle is a mystery. "I suspect it’s because there was no evolutionary imperative to get rid of them," says Dr Michael Berthaume, a bioengineering research associate at Imperial College London.
© Solo dmg media
