Articles

The Evolution of Insect Flight

by Matthew Vanhorn

According to evolutionary theory, insects were among the first creatures on the Earth to dwell on dry land. They supposedly originated in the Silurian Period, which lasted from 435 to 410 million years ago. The earliest known fossilized insect is said to have lived in the Devonian Period, which began 410 million years ago. Then suddenly, around 300 million years ago, winged insects appear in the fossil record. The evolution of insect wings and insect flight is an incredibly difficult concept for even the most studied evolutionists to explain.

Many theories have been proposed concerning the origin of insects’ wings. Conrad Labandeira, in the Encyclopedia of Paleontology, wrote that insects evolved from “an unspecified lineage of crustaceans” (1999, p. 603). Though many theories concerning wing evolution have been proposed, only two of them currently are accepted as plausible. The first of these theories is known as the paranotal theory, which proposes that wings originated from rigid lateral projections of thoracic terga (back of the insect) that gradually became larger. However, Labandeira admitted that “the theory suffers from several deficits, including absence of evidence” (p. 618). Indeed, “absence of evidence” is quite a deficit. The second (and more accepted) theory, called the epicoxal theory, suggests:

They grew out of a gill-like apparatus present in the very earliest insects. Some of these gills may have grown over time, after they were supplanted in the adults by trachea, to form little flaps. Initially, these proto-wings would have been useful for little more than jumping, perhaps adding a little to the distance over which insect could leap. Gradually, these wings would have grown larger, until they could be used for controlled diving, gliding, and then even flapping flight (p. 618)

INSECTS AND THE FOSSIL RECORD

These two theories notwithstanding, what does the evidence really show? Andrew Brodsky remarked in his book, The Evolution of Insect Flight, that the first 20 million years of insect evolution are “shrouded in mystery” (1994, p. 79). In their book, The Evolution of Life, Linda Gamlin and Gail Vines stated: “Arthropod fossil history dates back to 600 million years, but, unfortunately, there are no fossils of their earliest ancestors” (1987, p. 81).

Winged insects emerge suddenly in the fossil record, and even the oldest possesses exactly the same structures as their twenty-first century counterparts. Many dragonfly fossils from the Carboniferous Age have been found that possess the same structures as the dragonflies of modern times. Also, dragonflies and flies emerge instantaneously in the fossil record, together with wingless insects. This disproves the assumption that wingless insects developed wings and gradually evolved the musculature with which to utilize them in flight. Evolutionary scientists propose that insects have undergone extreme morphological alterations. Such drastic changes strongly suggest that something major occurred that prompted these changes. Robert Dudley, along with numerous other scientists, contends that insects developed their wings and flight in response to predation. Apparently, insects became tired of always getting eaten, so they began the twenty-million-year-long process of developing wings. But one should ask: What predators could insects have had 410 million years ago?

According to evolutionary timelines, the fossil record indicates that dragonflies were flying at least 350 million years ago. What do evolutionists speculate lived on land during this period? They believe only that insects and arachnids had evolved. There were no birds, no bats, and no aardvarks. Insects would have had very few predators from which to escape, if any. Did the insects go through twenty million years of trouble, just so that they could evade a few scorpions? Still, insects would not have needed to evolve a complex form of flight to escape from scorpions and spiders; they would just have to fly.

THE BIOMECHANICS OF INSECT FLIGHT:
FORM, FUNCTION, CREATION

Flying insects go far beyond “just flying.” Their aerial feats and maneuvers cannot be matched by any creature, other than the fascinating hummingbird. In his book, The Biomechanics of Insect Flight: Form, Function, Evolution, Robert Dudley attempted to explain how certain insects developed wings and flight mechanisms over millions of years. Insects require a highly specialized flight apparatus. Biomechanical prerequisites for insect flight include extremely powerful muscles in the thorax to generate force, axillary apparatus (the “shoulders” of the insects) to transfer force, and the wings themselves to convert force into flight. Most insects can perform a variety of aerial feats, because they possess a direct as well as an indirect muscular system. Direct muscles are attached directly to the wings, indirect muscles are not. The dorsoventral (midline on the back—MV) muscles contract to raise the wings. The longitudinal muscles contract to lower the wings. When the dorsoventral muscles contract, the tergum (back segments—MV) is lowered and the wings rotate about the other hinges and rise. When the longitudinal muscles contract, tergum is forced up again and the wings rotate in the opposite sense about the outer hinges. Additionally, insects are able to flap their wings in figure-eight patterns because of their dorsoventral muscles that are attached to the wing base.

As a result of their unique musculature, insects can beat their wings much faster than birds, which possess a direct muscular system. Humans also possess a direct muscular system. Break from your reading for a moment and try something. Extend your arms out to your sides parallel with your shoulders. Now flap your arms as fast as you can for five seconds. I would be impressed if you could flap twenty times. Insects can beat their wings up to 1,000 times in one second. This feat is a result of their unique muscular system as well as the unique design of the insect’s brain. The muscles themselves require few orders from the brain. When a human flaps his arms, his brain has to command each stroke on each side of his body. The insect’s brain does not have to think about every wing beat; it only needs to instruct the wings to begin or stop flapping.

When you flapped your arms, you probably not only looked silly to those around you, but you probably also became tired very quickly. Now imagine flapping your arms 200 times as fast! This would cause even the strongest of humans to collapse from exhaustion. The metabolic rate of all flying creatures is extremely high in relation to land-dwelling creatures. Dudley even found himself confessing: “Flight is energetically very costly, and the metabolism of winged insects represents an extreme of physiological design among all animals” ( Dudley, 2000, emp. added).Insects do not have a central breathing organ (like lungs); instead, oxygen is supplied to the flight muscles via the insect’s tracheal respiratory system. Insects do not breathe as humans do. They do not pull air in, but simply diffuse gases that pass through the tracheal respiratory system. This system comprises up to 10 percent of the insect’s body mass. The whole body is equipped for flying, yet many scientists purport that it is an evolutionary accident that they are able to fly.

Researcher Michael Dickinson attributed the aerodynamic feats of insects to the phenomena of delayed stall, wake capture, and rotational circulation. Delayed stall occurs when an aircraft’s wing cuts through the air at too steep of an angle. Vortices created by airplanes usually leave behind a pestering turbulence in the slipstream. However, insects require these vortices to remain in flight. A vortex is a rotating flow of fluid, such as occurs in a draining bathtub. When proceeding at shallow angles, the air splits at the front of the wing and flows smoothly in two streams along the upper and lower surfaces. The upper flow travels faster, resulting in a lower pressure above the wing. This draws the wing upward, producing lift. The first stage of stall initially increases the lift because of a brief flow structure called a leading-edge vortex. This type of vortex forms directly above and behind the wing’s leading edge. Airflow in the vortex is extremely fast, and the resulting low pressure adds substantial lift.

In addition to delayed stall, Dickinson discovered that the wings generated temporary strong forces at the beginning and end of each stroke that could not be explained completely by the stall. These force peaks occurred during stroke reversal, when the wing decelerates and rapidly rotates, suggesting that the rotation itself might be responsible. Dickinson illustrated the idea of rotational circulation by using a tennis ball. A tennis ball hit with backspin pulls air faster over the top, causing the ball to rise, whereas topspin will pull air faster underneath, causing the ball to sink. Dickinson concluded that flapping wings develop significant lift by rotational circulation.

Finally, Dickinson discovered that wake capture—the collision of the wing with the swirling wake of the previous wing stroke—assists in the flight of insects. Each stroke of the wing leaves behind a complex of vortices. When the wing reverses direction, it passes back through this churning air. A wake contains energy lost from the insect to the air, so wake capture provides a way for the insect to recycle energy.

The evolution of insect wings and subsequent flight is a concept impossible for evolutionists to explain. Insects are the ultimate flying machines—even humans’ most state-of-the-art aircraft cannot match the flight of insects. There is no way that the insects could have gradually evolved flight, nor is there fossil evidence of any intermediate species of insect between flying and non-flying insects. The fossil record indicates that if, in fact, flight evolved in insects, then it did so very rapidly. However, such a rapid, complex evolutionary advancement is impossible, and even goes against evolutionary theory. All of the evidence exemplifies elaborate design, and documents that everything was created fully functional in the beginning. All evidence points toward the intelligent design of insect flight—its form, function, and creation.

REFERENCES

Brodsky, Andrew (1994), The Evolution of Insect Flight ( New York: Oxford University Press).

Dudley, Robert (2000), The Biomechanics of Insect Flight: Form, Function, Evolution ( Princeton, NJ: Princeton University Press).

Gamlin, Linda and Gail Vines (1987), The Evolution of Life ( New York: Oxford University Press).

Labandeira, Conrad (1999) “Insects and Other Hexapods,” Encyclopedia of Paleontology ( Chicago, IL: Fitzroy Dearborn), 1:603-624.

http://www.apologeticspress.org/articles/2534