Inside the stout fins of a fish that prowled the shallow waters of an estuary in what is now eastern Canada about 380 million years ago, scientists have found what they call the evolutionary origins of the human hand.

The researchers examined a remarkably complete fossil of a fish called Elpistostege watsoni that represents a pivotal stage in a landmark event in the history of life on Earth - the transition of fish to land vertebrates.

For this to occur, anatomical changes were needed including the evolution of hands and feet. Inside the tip of Elpistostege’s front fins - called pectoral fins - were tiny bones called radial bones arranged in a series of rows like digits - the precursor to fingers. These would have provided the flexibility for Elpistostege’s fin to bear weight on land.

“By looking at Elpistostege, it is important to realize that we, as human beings, are coming from a long line of evolution, that every part of our body, like our fingers, has a long evolutionary history,” said paleontologist Richard Cloutier of Université du Québec à Rimouski in Canada, lead author of the research published in the journal Nature.

“This is true for Homo sapiens but it is also true for all living organisms,” Cloutier added.

This marks the first time such traits have been found in a fish rather than in the earliest amphibians - the first land vertebrates - that later evolved from fish with sturdy fins like Elpistostege. It had two explicit digits and three other apparent digits.

