Page 45 - Design in Nature

Flawless Flying Machines: Birds 43

structure of a feather.
Feathers are constructed of a protein substance called keratin. Keratin
is a hard and durable material that is formed by the old cells that migrate
away from the nutrient and oxygen sources in the deeper layers of the skin
and die in order to give way to new cells.
The design in bird feathers is so complex that the process of evolution
simply cannot explain it. Scientist Alan Feduccia says feathers "have an
almost magical structural complexity" which "allows a mechanical
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aerodynamic refinement never achieved by other means". Although he is
an evolutionist, Feduccia also admits that "feathers are a near-perfect
adaptation for flight" because they are lightweight, strong, aedodynamically
shaped, and have an intricate structure of barbs and hooks. 15
The design of feathers also compelled Charles Darwin ponder them.
Moreover, the perfect aesthetics of the peacock's feathers had made him
"sick" (his own words). In a letter he wrote to Asa Gray on April 3, 1860, he
said "I remember well the time when the thought of the eye made me cold
all over, but I have got over this stage of complaint..." And then continued:
... and now trifling particulars of structure often make me very
uncomfortable. The sight of a feather in a peacock's tail, whenever I
gaze at it, makes me sick! 16

Small Barbs and Hooklets
One encounters an incredible design if the feather of a bird
is examined under the microscope. As we all know, there is
a shaft that runs up the centre of the feather.
Hundreds of small barbs grow on either side of
this shaft. Barbs of varying softness and size
give the bird its aerodynamic nature.
Furthermore, each barb has thousands of
even smaller strands attached to them called
barbules, which cannot be observed with the
naked eye. These barbules are locked together
with hooklike hamuli. The barbules hold on to one