Wings that aren’t: Milos Radakovich

Ostrich

Ostrich

In 1798, sixty years before Charles Darwin’s first book was published, a French anatomist, Étienne Geoffroy St. Hilaire, traveled to Egypt with Napoleon where he witnessed and wrote about a flightless bird whose wings appeared useless for soaring. The bird that Hilaire described was the cassowary, and it is one of several birds that have wings that are vestigial. Besides the cassowary, other flightless birds with vestigial wings are the ostrich, emu, kiwi, dodo, flightless cormorant, and the kakapo (a flightless nocturnal parrot). There are, and have been, many other examples. In general, the wings of a bird are considered complex structures that are specifically adapted for flight and those belonging to flightless birds are no different. They are, anatomically, rudimentary wings, but they could never get these bulky birds airborne. The wings of flightless birds are not completely useless, as they are used for defense, for balance while running, camouflage and temperature control, and in flagging down potential mates during courtship displays. Penguins use their wings for flight, but underwater, instead of through air. The capacity for flight has been invented and reinvented countless times throughout the evolutionary history of fish, insects, reptiles, mammals, and, of course, birds. At many places along the way, that ability was lost or traded for something that conferred even better survival value, yet leaving the rudimentary wing structures in place.

Milos Radakovich

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