The Flamingo’s Smile Read Free Page B

recalls the hump on a camel’s back, but because it mimics the bend of the nose that imparts an inappropriate (but unshakable) impression of haughtiness to both animals (see my essay on the history of Mickey Mouse and the messages accidentally conveyed by facial features of animals—essay 9 in The Panda’s Thumb ). Turned upside down, the hump becomes a grin as a smiling “swan” replaces the haughty flamingo.

    The famous flamingo, FROM J.J. AUDUBON’S Birds of America .
    The bills are elaborately adapted to their reversed roles, not simply bent in the middle for proper reorientation. First, relative sizes have been rearranged to complement the shapes. The upper bill is small and shallow, the lower deep and massive. (In most birds, the smaller lower bill moves up and down against the larger upper beak.) Second, the flamingo’s lower bill (functionally upper in feeding) has evolved unusual rigidity. The bones of each half (or ramus, in technical parlance) are tightly fused, and the rami themselves are then bonded extensively to each other. The lower bill is massive and well braced. The tongue runs fore and aft in a deep trough cut into the lower jaw. (Remember that filter feeding serves as a coordinating theme for all these changes—the upside-down feeding posture, the attendant alteration in size and shape of the bills, and the fat tongue that once almost sealed the flamingo’s fate.) Third, in most species of flamingo, the smaller upper jaw slots into a receiving space on the larger lower jaw, a reversal of the usual convention—lower jaw moving up and fitting into a larger upper bill.
    These complex, coordinated changes make a persuasive case, but they leave a missing piece, recognized as the key to flamingo peculiarities ever since Menippus recorded the first preserved speculation nearly 300 years before Martial’s plea: are movements also reversed to match the inversion of form?
    In most birds (and mammals, including us), the upper jaw fuses to the skull; chewing, biting, and shouting move the mobile lower jaw against this stable brace. If reversed feeding has converted the flamingo’s upper jaw into a working lower jaw in size and shape, then we must predict that, contrary to all anatomical custom, this upper beak moves up and down against a rigid lower jaw. The flamingo, in short, should feed by raising and lowering its upper jaw.
    With great credit to the clear thinking of our finest naturalists, I noted with pleasure in my readings that this central question has been continually posed as paramount for more than 2,000 years—by scientists of many cultures and through all the vicissitudes of theory and practice that have marked the history of biology. Georges Buffon, the greatest of all synoptic naturalists, began his mid-eighteenth-century essay on flamingos by admitting the fame of their red color, while maintaining that the odd form of their beak posed a problem of even greater interest: “This fiery color is not the only striking character displayed by this bird. Its beak has an extraordinary form, the upper bill flattened and strongly bent at its midpoint, the lower thick and well set, like a large spoon.” In short, and in his own lovely tongue, “une figure d’un beau bizarre et d’une forme distinguée.” Then, tracing the question right back to Menippus, Buffon stated the primum desideratum of flamingo studies—“to know if, in this singular beak, it is (as many naturalists have said) the upper part that moves, while the lower remains fixed and motionless.”

    Nehemiah Grew’s flamingo, 1681. The illustration accompanying the first important proposal that flamingos feed by moving their upper jaw up and down against their lower. Look at this figure upside down as well. FROM N. GREW, MUSAEUM REGALIS SOCIETATIS, 1681. REPRINTED FROM NATURAL HISTORY .
    The first extensive and explicit commentary had been offered in 1681 by Nehemiah Grew, the great English naturalist (known primarily for his