Flinders University research reveals origins of human hand in fish ‘fingers'

The bony structure of human hands first took shape in ancient fish, 380 million years ago, Flinders University and Canadian research shows. These ancient marine predators were just starting to reach for land. SEE THE VIDEO.

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Evolution of the hand and fingers has been traced back to the bones in a fossilised fish fin that are about 380 million years old.

Flinders University palaeontology Professor John Long says the research published today in the journal Nature reveals “extraordinary new information about the evolution of the vertebrate hand”.

“The articulating digits in the fin are like the finger bones found in the hands of most animals,” he said.

“This finding pushes back the origin of digits in vertebrates to the fish level, and tells us that the patterning for the vertebrate hand was first developed deep in evolution, just before fishes left the water.”

The evolution of fishes into tetrapods, four-legged vertebrates, to which humans belong, was one of the most significant events in the history of life. Vertebrates (backboned animals) were then able to leave the water and conquer land.

The fossil of the ancient elpistostege fish, a large marine predator, was found in Miguasha, Canada. Scientists from the Universite du Quebec a Rimouski in Canada collaborated with colleagues at Flinders.

Co-author Richard Cloutier from Universite du Quebec a Rimouski says the fish is not necessarily our ancestor, but it is closest we can get to a true ‘transitional fossil’, an intermediate between fishes and tetrapods.

“The origin of digits relates to developing the capability for the fish to support its weight in shallow water or for short trips out on land,” he said.

“The increased number of small bones in the fin allows more planes of flexibility to spread out its weight through the fin.

“The other features the study revealed concerning the structure of the upper arm bone or humerus, which also shows features present that are shared with early amphibians.”

The 1.57m specimen shows the complete arm (pectoral fin) skeleton for the first time in any elpistostegalian fish.

Using high energy CT-scans, the skeleton of the pectoral fin revealed the presence of a humerus (arm), radius and ulna (forearm), rows of carpus (wrist) and phalanges organised in digits (fingers).