New ‘Paleo-Robots’ Could Shed Light on Animal Evolution, Revealing How Some Fish Evolved to ‘Walk’ on Land

Life on Earth started in the oceans. Beginning around 390 million years ago, however, the ancestors of modern land animals rose out of the waters, trading their fins for limbs and gills for lungs. This was a crucial transition in the evolution of all creatures—including humans—that walk the planet today.

Now, a team of roboticists, paleontologists and biologists are using robots inspired by both living and extinct animals to shed light on this and other pivotal evolutionary transformations. They detailed their work in a review article published in the journal Science Robotics last week.

“Building a robot … will hopefully give us a little bit of insight into what kind of evolutionary pressures, or what kind of mechanics, started to force fish to develop these different anatomies that would be useful on land,” article co-author Michael Ishida, a roboticist in the Bio-Inspired Robotics Lab at the University of Cambridge in England, tells the Guardian’s Nicola Davis.

Fossil evidence from the water-to-land transition is limited, and it doesn’t allow researchers to test the motion of hip and pelvic joints—parts of the body that are crucial to movement in vertebrate animals. So, the team is trying to fill those knowledge gaps by building energy-efficient fish robots with mechanical joints, muscles and ligaments. Their machines are inspired by the anatomy of existing “walking fish,” like mudskippers, as well as fossils of extinct fish species.

The researchers want to understand the amount of energy it takes for the creatures to walk in certain patterns, with the aim of pinpointing which movements would have been most efficient—and thus might have led the way toward marine animals evolving to walk on land.

“In the lab, we can’t make a living fish walk differently, and we certainly can’t get a fossil to move, so we’re using robots to simulate their anatomy and behavior,” Ishida says in a statement from the University of Cambridge.

The first step in building paleo-inspired robots is to understand an extinct animal’s anatomy, including how its joints worked and how its muscles and bones connected, Paul Smaglik writes for Discover magazine. Then, the team matches the extinct animal with a close living relative and uses video and computer vision techniques to translate the modern animal’s movements into mathematical representations.

Finally, they combine the knowledge from both the extinct species and the live one to build a simple robot that uses parts such as rods, springs and dampers instead of bone, flesh and cartilage.

“In some cases, we’re just guessing how certain bones connected or functioned,” Ishida says in the statement. “That’s why robots are so useful—they help us confirm these guesses and provide new evidence to support or rebut them.”

For those wondering why the scientists wouldn’t just use computer simulations, they explain it’s because robots can be placed in real environments with terrains, such as sand or mud, that would be complicated to simulate in a model, per the Guardian. Then, the team can put the robots through experiments to understand evolutionary pressures and advantages.

“Roboticists can test the effects of millions of years of evolution in a single day,” Ishida explains to Discover. The scientists can also make small adjustments to the code or print a new piece of the robot in minutes—changes that would have taken millennia in a real animal.

“It would be mesmerizing to build a robot to, say, understand how giant dinosaurs walked and moved. But what is especially exciting to me is the potential of using robots to study major evolutionary transitions,” Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the report, tells the Guardian. “These robots can help us test hypotheses about the history of life.”

The team is still in the early stages of robot construction, and in addition to the water-to-land transition, they also hope to eventually study the evolution of flight and how some animals transitioned to walking on two legs.

They’re not just looking into the past, however. Similar robots could provide insight into the evolutionary changes that are happening to animals today—as a result of pressures such as human activity and climate change—to imagine how species will look in the future.

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.