Washington: A study on a robot with flapping wings have put weight on the theory that avian flight evolved from tree-dwelling animals, and not from land animals.
In order to gain an insight into the evolution of early birds and insects, a six-legged, 25-gram robot has been fitted with flapping wings.
The study showed that although flapping wings significantly increased the speed of running robots, the origin of wings might lie in animals that dwelled in trees rather than on the ground.
Fossils of animals closely related to dinosaurs, dating back further than when birds actually emerged, show that feathers were present on all four limbs, suggesting that the original function of wings was to help animals glide when dropping from a height, much like a paper aeroplane.
An alternative theory is that the first wings may have appeared in land-based animals, functioning as a mechanism to increase running speeds and then leading to take-offs and flying thereafter.
The researchers, from the University of California, Berkley and the Smithsonian Tropical Research Institute, aimed to gauge how much of an advantage flapping wings give a running animal.
“By using our robot we can directly determine the performance effects of flapping wings on a running platform as well as gaining a much greater mechanical insight into how the wings are actually working on the robot,” said Kevin Peterson, lead author of the study.
“We are thus able to look at the performance of the wings directly rather than attempting to build theoretical aerodynamic models based on fossil morphologies that may be overly sensitive to various assumptions,” said Peterson.
The researchers concluded that flapping wings do provide an advantage to running robots but not to the level that is needed to allow it to take off.
“We believe that this result lends indirect support to the theory that avian flight evolved from tree-dwelling animals, and not from land animals that required ground-based running take offs,” he added.
The study has been published in IOP Publishing’s journal Bioinspiration and Biomimetics.