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Thursday, 19 July 2007

Nature had it first--and had it right the first time!


There appear to be two languages spoken by scientists. Here is an example of the one, in which they study nature in a detached and condescending way, as if they could have done a far better job if they were in charge:
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"Phylogenetic group contributed in a highly significant way to explain the considerable variation in bird flight speeds that remained, even after the biometrical dimensions of the bird species had been taken into account," Alerstam reported.

This matches what would be expected from evolution, says Tobalske. Instead of making a perfect bird, evolution does the best it can from the animals that are around to evolve flight. What’s more, he said, the real world is always changing in unpredictable ways that require birds to adapt to keep pace or die out. Few adaptations that help different birds survive also make them the best fliers.

It’s an example of what’s called the Red Queen Hypothesis, said Tobalske, referring to the character in Lewis Carroll’s Through the Looking Glass.

"The Red Queen is running just to stay in place," Tobalske told Discovery News. Evolution does the same with birds: keeping them in constant evolutionary motion, but never allowing them to get any closer to aerodynamic perfection.

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Here is an example of the other, in which they stand in awe and practically stutter at the perfection they observe in nature, one far beyond their ability to produce or even predict (I lost the example I was going to use, but this will have to do for now):

"The researchers found that the major factors involved in determining ideal wing position were speed, and the angle of the wings relative to the ground. Not surprisingly, extended wings were best for slow gliding, since they increase lift and allow the bird to float longer on a breeze. As speed picks up, drag forces increase and swept-back wings become more advantageous.

The results on turning were more surprising. In general, extended wings are better for turns, providing stability and lift that smooth the turn. For high-speed turns, however, swifts invariably sweep back their wings, and the researchers discovered that this behavior is due not to aerodynamics, but to the fragility of their wings. Extended wings can fracture under the extreme force generated during a fast turn, while swept-back wings are safe, mostly because they don't flutter.

The realization that extended wings are vulnerable to breakage during fast turns is one of several aspects of the study that may be useful in designing aircraft. Another is the proof that fully extended wings are best for generating lift; previous studies with artificial wings had suggested that swept-back wings actually give a better boost. A few high tech planes, such as the F-14 Tomcat fighter plane, already use flexible wings, but Lentink hopes his findings will help make aircraft wings even more efficient. Tomcats can sweep back their wings when they fly at super high speeds, but their abilities are primitive compared to those of swifts. "The swifts are just better at it," he told "The amount of feathers and muscle involved is challenging for us to imitate."

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For some odd reason, articles of the second sort are typically rife with factual errors. Articles of the first sort could often be considered free of these, but only because they are almost pure hypothesis, without any factual claims subject to being disproven.

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