Robo-salamander's evolution clues

The mechanical salamander is a tool to study the past

A robot is being used by a Franco-Swiss team to investigate how the first land animals on Earth might have walked.

The bot looks a lot like a salamander; and the scientists can change the way it swims, slithers and crawls with commands sent wirelessly from a PC.

The group says it provides new insight into the nervous system changes aquatic lifeforms would have had to acquire to move to a terrestrial existence.

The researchers report their study in the latest edition of Science magazine.

A decapitated chicken that runs for a while even without the brain is a good example of spinal cord regulation of locomotion Auke Jan Ijspeert

By mimicking the nervous system and the movements of the salamander, the team hoped "to decode perhaps some of what happened during evolution", Auke Jan Ijspeert, of Ecole Polytechnique Federale de Lausanne, told BBC News.

Simple systems

The first animals capable of walking on land are thought to have emerged during the Devonian Period.

The transition is a crucial period in Earth history Fossils mark move to land

Palaeontologists have found fossils dating back some 360 million years that show a process where fins are transformed into limbs.

Before the appearance of these tetrapods - four-legged vertebrates that mostly live on land - all backboned animals were confined to water.

Precisely how they came out on to the shore is not clear - but the latest research indicates the transition would not have required a huge leap in brain power.

Mr Ijspeert and colleagues have shown how even the simple nervous system of a lamprey (a primitive eel-like fish) can, with a few modifications, drive walking motion in a creature that resembles a salamander.

The computer system that runs their robot is based on just such a nervous system; it is no more complex.

Chicken heads

The computer sends signals through the machine's "spinal cord" to the limbs, allowing the bot to switch effortlessly between swimming and walking.

The robot was tested on the shores of Lake Geneva

The scientists chose a salamander as the inspiration for their mechanical animal because the amphibian is probably quite similar to the first vertebrates that lived on land.

When it swims, it does so like a fish - its body makes undulating movements, with its limbs folded backward.

On firm ground, however, the salamander changes to a slow stepping gait, in which diagonally opposed limbs are moved together while the body makes S-shapes.

The research group has demonstrated how salamanders can control their locomotion using largely just their spinal cord.

"Their brains are more or less only involved to regulate the speed and direction," said Mr Ijspeert.

"A decapitated chicken that runs for a while even without the brain is a good example of spinal cord regulation of locomotion."