Evolutionary Miracles?



Fortuitous Flaws. If you're a student of physics, you know that honey bees shouldn't be able to fly at all. 

The secret of honeybee flight is an unconventional combination of short, choppy wing strokes, a rapid rotation of the wing as it flops over and reverses direction, and a very fast wing-beat frequency that is uncommon of an insect this large. 

Aerodynamic performance decreases with size, and so to compensate, small animals have to flap their wings faster. Mosquitoes flap at a frequency of over 400 beats per second. Being relatively large insects, honey bees would be expected to beat their wings slowly and to sweep them across the same wide arc as other flying insects. They do neither. Honey bee wings beat over a short arc of about 90 degrees, but vigorously fast, at around 230 beats per second. Fruit flies, in comparison, are 80 times smaller than honeybees, but flap their wings only 200 times a second.

Why? Honey bees have evolved flight muscles that are physiologically very different from those of other insects. One consequence is that the wings have to operate fast and at a constant frequency or the muscle doesn't generate enough power. Researchers cite that bee ancestors inherited this kind of muscle and now present-day bees must live with its peculiarities. A fortuitous flaw that allows honey bees to fly, pollinating most of the plants that provide food for our planet.—N.B.

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