are among the insect world's most powerful fliers.
good is half a wing?" asked Darwin's skeptical contemporaries.
It is a question that cuts to the heart of evolution theory.
If evolution proceeds in steps, how can something as complex
as flight - and the necessary wings, nerves and muscles -
In "Taking to the Air," Alan meets Pennsylvania State University
biologist Jim Marden,
who demonstrates exactly what evolutionary advantage half
a wing might have had 350 million years ago before insect
clip stonefly wings to get to the roots of flight evolution.
Marden and his student Melissa Kramer looked to the rivers
of eastern Pennsylvania, where insects called stoneflies hatch
and rush to shore to find a mate. The winged but flightless
stoneflies use their wings to propel themselves across the
surface of the water.
in their lab, Marden and Kramer time the speed of the flies
as they skim across the water. Then the scientists clip their
wings and time them again. Even with their wings clipped down
to little nubs, the stoneflies can still propel themselves
across the water's surface. And that improves their chances
of finding a mate. So that's what half a wing is good for.