It’s A Bird… It’s A Plane… It’s a Robotic Bug.
Dr. Ron S. Fearing and a team of engineers at the University of California, Berkeley gave Dash (Dynamic Autonomous Sprawled Hexapod), a six-legged robot wings to increase its running speed and improve its stability. The researchers report in the journal Bioinspiration and Biomimetics that attempts to fly with the appendages were no match for gravity – the critter was unable to take flight from the ground. The findings shed light on a longstanding debate about the evolutionary origins of flight.
The researchers applied the appendages on the robotic bug to gauge how much of an advantage flapping wings give a running animal. According to Kevin Peterson, lead author of the study, “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. 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.”
Relying on scant fossil evidence and theoretical models, scientists debate whether birds first evolved flight as ground dwellers or tree jumpers. Proponents of the Trees-down Theory (first articulated by Othniel Charles Marsh in 1880) argue that flight developed from gliding, as birds soared short distances amongst the branches of trees. Over time, incremental changes to the wings and feathers enabled birds to fly more efficiently. Advocates of the Ground-up Theory (cursorial) (first articulated by Samuel Wendell Williston in 1879) claim that ancestral birds hopped up from the ground to catch prey and experienced incremental morphological modification to better survive and reproduce.
Peterson and his team believe the results lend “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.”
However, supporters of an alternative theory called the pouncing proavis model (first proposed by Garner, Taylor, and Thomas in 1999) believe that birds evolved from predators that specialized in ambush from elevated sites. The authors argue that neither the arboreal nor cursorial theories adequately account for the complexity of evolution of flight in birds.
The origin of wings in the frequently inhabited skies remains a hotly debated topic.