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Words of a Feather

by  Matthew Vanhorn

At first glance, the feather seems to be not much more than a colorful piece of fluff. One might wonder how such a seemingly simple thing found in nature could represent a decisive case for Creation. But feathers do indeed offer powerful evidence. Feathers exemplify the wonders of intelligent engineering, and indicate incredible design. Feathers are a unique integument [natural outer covering] that belongs only to birds, and are described by Richard Prum as “the most complex epidermal appendages found in animals” (1999, p. 291). Consider the feather’s state-of-the-art design.

Each feather has a shaft that runs along the center. The fluffy strands that extend from the shaft are called vanes. Each vane is composed of even smaller thread-like strands, called barbs. These various barbs allow the feather to achieve lift. But the structure is even more streamlined. On either side of the barb are microscopic barbules. One side has barbules comprised of ridges, whereas the other side is composed of hooks. The hooked barbules thus attach to the ridges of the adjacent barbules, forming a sort of natural Velcro®. Actually, the feather has a better design than Velcro, because the ridges allow the barbs to slide, keeping the surface intact, and yet allowing it the flexibility required for flight. Thus, it can be said that birds of a feather flock together, and feathers of a bird lock together.

Diagram of a feather
Illustrated by Thomas A. Tarpley
© 2004 AP

Cross-section of two barbs showing how their barbules “hook” together.
KEY: A. Shaft (Rachis); B. Vane; C. Barbs; D. Hooked barbules; E. Ridged barbules.

The complexity of the feather does not stop here, though. The sliding joint made by the hooked and ridged barbules needs lubricating oil. Once the barbs of a feather have been separated, it is difficult for them to come back together. But the owner of the feather has been given a solution to this problem. The bird spends much of its time preening—methodically combing, smoothing, cleaning, and lubricating its feathers. The bird secretes a special preening oil from a gland at the base of its spine. Without this special oil, the birds would be useless in flight. This oil also allows birds to be waterproof, and simultaneously prevents heat loss. The many outstanding characteristics of the feather caused Roger Peterson to write:

The feather is a marvel of natural engineering. It is at once extremely light and structurally strong, much more versatile than stretched skin on which a bat supports itself in flight, or the rigid structure of an aircraft’s wings—and far more readily repaired or replaced when damaged.... Though nearly weightless it has strength. The stiff shaft of the quill provides rigidity when support is needed, yet it is supple towards its tip, when flexibility is required for split second aerial maneuvering. Feel the sleekness of the web, soft yet firm. Separate the barbs; zipper them together again by running them through the fingertips as a bird would preen with its bill. The intricacy of the design that allows this can be appreciated by putting the feather under microscope (1963, p. 33, emp. added).

Feather design enables birds to ride air currents more gracefully than the best aircraft that engineers have designed. If, like in the case of the ostrich, the barbs have no hooklets, then the bird will not be able to fly. Hooklets are designed so that they can separate under certain conditions, preventing wind damage to the wing and feathers, yet can be easily reattached when the bird preens its feathers. Preening behavior is part of the irreducible complexity of the total feather design.

Feathers must be designed to give the bird lift by causing the air on the top surface to flow faster then the air on the bottom surface (a situation known as the Bernoulli Effect). Flight feathers (often called contour feathers) accomplish lift with the smaller vane on the leading edge in direct contact with the air during flight. Birds need feathers to fly, but feathers also give the bird much-needed protection against adverse weather, especially cold air and water. “Overlapped like shingles and coated with a layer of oil, feathers protect the bird from water and heat loss much like roof shingles help to protect a house” (Bergman, 2003, p. 3).

FEATHER FACTS IN THE FOSSIL RECORD

In an article that appeared in American Zoologist ( “Explanatory History of the Origin of Feathers”), Walter Bock wrote: “The factual knowledge available on which we can speculate on the evolution of the avian integument is most scanty” (2000, 40:480). There is much known about the biological roles of the skin and feathers in recent birds. There is also much known about current reptilian scales. What we do not know, are any intermediate “repti-birds.” Bock continued: “Fossil remains of the skin of reptiles are rare and tell us little to nothing about the morphology of scales in possible avian ancestors among the reptiles…. We lack completely fossils of all intermediate stages between reptilian scales and the most primitive feather” (40:480, emp. added). The same “complicated morphology” is present in all feathers found in the fossil record.

“The oldest known feathers from the Late Jurassic are already modern in form and microscopic detail” (Martin and Czerkas, 2000, 40[4]:687). Acknowledged feather expert Alan Brush theorized about how a feather might have evolved from reptilian tubercles rather than scales.

The very early steps in the evolution of a protofeather largely reflect the development of modern epidermal structures…. A tubercle-like morphology was involved. Similar structures have been found on dinosaurs and living reptiles. Tubercles afford the formation of filament, quite possibly one that is hollow. The early feather bud would have been radially symmetrical. The barb ridges would have produced columns rather than plates of cells…. Hence, the tubercle would have represented a rather complete morphogenic unit (2000, 40:634).

Unfortunately for Dr. Brush, his theories have little, if any, evidence to support them. The discovery of Archaeopteryx (which allegedly existed 145 million years ago) led to the dinosaur-bird hypothesis which suggested that modern birds evolved from dinosaurs. However, these findings, originally hailed as proof of evolution in action, turned out to be wrong (see Harrub and Thompson, 2001).

THE ORIGIN OF FEATHERS—IN THEORY

There are two major theories in the evolutionary realm concerning the evolution of feathers: (1) the flight theory; and (2) the insulation theory. The flight theory suggests that primitive feathers were flight feathers that derived from elongated scales along the back of the reptile’s forelimbs. With this, the creature eventually evolved flight by gliding from trees. As the scales became longer, they became frayed, and developed into the barbed structure of feathers. The feathers then spread over the rest of the body.

Those who advance the insulation theory claim that primitive feathers were a type of contour feathers, and did not have to be good insulators. Since birds are warm-blooded, they must find a way to prevent heat loss in order to survive in cooler climates. The air spaces between the feathers act as effective insulators. This function is so integral to the bird’s survival that many Darwinists have theorized that feathers actually originated as an insulating device, and only later facilitated flight (see Bock, 2000).

Much disagreement exists about the role of thermoregulation in feather evolution. Kenneth Parkes argued that if “the primary ‘need’ of the avian ancestor” was for “an epidermal outgrowth...useful as a thermoregulatory mechanism, why ‘bother inventing’ anything as complex as a feather? Hair would have been much simpler!” (as quoted in Bock, 40:481). Actually, a hair-like structure is better for insulation! For this reason, some argue that feathers evolved to help cool the bird by functioning as “Sun shades” that reduce the level of heat absorption (40:481). Bock concluded that the thermal theory of feather evolution is, at best, only “a poorly tested theory.”

Although I feel that a rather satisfying explanation can be offered for the insulation theory of the evolutionary origin of avian feathers, this explanation can be offered only as a poorly tested theory and one that probably cannot be tested any better than it has been to date. And the insulation explanation, much as I might prefer it, is no better tested than the flight theory for the origin of feathers (40:484).

It seems strange that for insulation purposes, a bird would, by chance, also evolve flight and waterproofing capabilities. Brush made a similar comment: “The question of why a relatively complex machinery was necessary to produce a relatively simple object is not directly answerable” (Brush, 2000, 40:639).

These theories, as it turns out, are mostly the product of guesswork. “What is found consistently in the fossil record is fully developed scales, feathers that are fully feathers, and skin that is clearly skin” (Bergman, p. 5). No transitional structures consisting of feathers that are part feather and part scale, or even feathers that are less than modern types, have ever been uncovered (Bergman, p. 5). Bock was forced to admit:

There is still the unanswered puzzle of the morphology of the primitive feather—whether it was a simple contour feather with or without a downy base, whether it was a contour feather with an aftershaft, whether it was a downy feather, or whether it was a flight feather. Was the primitive feather water-proof or, better said, water resisting? No empirical evidence exists with which to test it (40:482).

Phillip Regal added: “Evolutionary theories relating to the origin of feathers and flight (and even heat conservation) are all inadequate, and evidence for such an evolutionary origin is nonexistent” (1975, p. 35).

The feather is yet another decisive design found in nature. It has long been a sore spot for evolutionists, and apparently will continue to be. Examination of the evidence leads to one obvious conclusion. Feathers could not have evolved. Rather, they are the product of an intelligent Cause. They are the result of the divine planning of a beneficent Creator.

REFERENCES

Bergman, Jerry (2003), The Evolution of Feathers: A Major Problem for Darwinism, [On-line], URL: www.answersingenesis.org/home/area/magazines/tj/docs/
v17n1_feathers.pdf.

Bock, Walter J. (2000), “Explanatory History of the Origin of Feathers,” American Zoologist, 40:478-485.

Brush, Alan H. (2000), “Evolving a Protofeather and Feather Diversity,” American Zoologist, 40[4]:687-694.

Carroll, Robert (1997), Patterns and Processes of Vertebrate Evolution (New York: Cambridge University Press).

Harrub, Brad and Thompson, Bert (2001) “Archaeopteryx, Archaeoraptor, and the ‘Dinosaurs-to-Birds’ Theory,” Reason & Revelation, April, 21:25-31.

Martin, Larry D. and Stephen A. Czerkas (2000), “The Fossil Record of Feather Evolution in the Mesozoic,” American Zoologist, 40[4]:687-694.

Parkes, Kenneth (1966), “Speculations on the Origin of Feathers,” Living Bird, 5:77-86.

Peterson, Roger Tory (1963), The Birds (New York: Time).

Prum, Richard O. (1999) “Development and Evolutionary Origin of Feathers,” Journal of Experimental Zoology (Molecular, Developmental, Evolution), 285:291-306.

Regal, Philip (1975), “The Evolutionary Origin of Feathers,” The Quarterly Review of Biology, 50[1]:35-66.




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