SCIENTISTS now believe humans evolved from a five-centimetre-long worm-like creature that wriggled in the sea more than 500 million years ago.
The extinct Pikaia Gracilens has been confirmed as the oldest known member of the chordate family, which includes all modern vertebrates including humans.
It gave rise to the panoply of vertebrate animals alive today - fish, amphibians, birds, reptiles and mammals.
When Pikaia was first discovered in 1911 scientists assumed it was related to leeches and earthworms.
But a new study has now confirmed what many experts suspected, that the creature was a primitive ancestor of animals with spinal cords.
Every specimen of Pikaia discovered so far has come from the Burgess Shale fossil beds in Canada's Yoho National Park, which date back 505 million years.