According to Science magazine, prehistoric "toes" evolved about 40 million years ago. The anatomy of the first elephant by Scottish surgeons can be traced back to 1706. "This discovery is great. It solves a very mysterious mystery." Professor john hutchinson of the Royal Veterinary College said.

But this "sixth toe" is not like other five toes, nor is it a real toe, but a structure with toe function which is mutated from sesamoid.

In the past, some researchers found the sesamoid structure when dissecting elephants, but they all regarded it as a strange cartilage and did not pay much attention to it. Many museums do not add this "sixth toe" when setting up elephant specimens.

The elephant's "sixth toe" has been neglected for a long time because the elephant's sole is difficult to study. Living elephants are not easy to be anesthetized, and the thick soles of their feet are not easy to be X-rayed. Professor Hutchinson obtained many samples of elephant soles after death from the zoo. After comparative analysis, he finally confirmed this knot.