The oldest human ancestor is a 500million-year-old worm-like creature no longer than a thumb.
Pikaia gracilens is the most primitive known vertebrate and therefore the ancestor of all descendant vertebrates, including humans.
The tiny creature had the beginnings of a backbone and skeletal muscle making it the oldest ancestor like us.
It is a member of the chordate family, the group of animals that today includes fish, amphibians, birds, reptiles and mammals.
Pikaia, now extinct, averaged about five centimetres in length and has been found only in the Burgess shale fossil beds of Canada’s Yoho National Park.
It was first discovered in 1911 and thought to belong to the leech or earthworm... read more