Airplanes may have developed through many of the same forces that drove the evolution of birds and other flying animals. These were driven by the laws of physics that control flight.
Researchers believe both the dodo bird and the trans-Atlantic supersonic jet Concorde each ran into an evolutionary dead end.
"The evolution of Earth's species occurred on a timescale far too large for humans to witness. But the evolution of our use of technology and airplanes to transport people and goods has taken place in little more than a single lifetime, making it visible to those who look," Adrian Bejan, professor of mechanical engineering and materials science at Duke University and lead author of the study, said.
Bejan discovered a law of physics in 1996 that he believes guides both natural and artificial evolution of flight.
The Constructal law deduced by Bejan states that for a system to thrive, it must increase fluid flow. The human bodies evolved similar methods to rivers in order to best provide access to blood - and oxygen - for cells. Tree branches and highways also follow similar patterns to one another, as they strive to move water and cars along their lengths.
"[L]arger airplanes are faster, more efficient as vehicles, and have greater range. The engine mass is proportional to the body size: this scaling is analogous to animal design, where the mass of the motive organs (muscle, heart, lung) is proportional to the body size. Large or small, airplanes exhibit a proportionality between wing span and fuselage length, and between fuel load and body size," researchers wrote in an article announcing their discovery.
Airplanes have been required to ferry a greater number of people - and greater loads of cargo - for great distances over the last several decades. New airplanes have been introduced, both large and small, but the largest of all models in general use have grown more massive over time. Larger aircraft have required longer wingspans and fuselages, along with more massive engines and increasingly larger fuel loads.
When velocity was graphed against body size for animals and aircraft, the two lines followed nearly parallel paths. The Concorde was far out of the norm for this development, carrying few passengers and consuming large quantities of fuel.
Aerospace companies may be able to make use of this research, to design more efficient aircraft.
Investigation of the parallels between natural evolution in flying animals and development of mechanical aircraft was detailed in the Journal of Applied Physics.