How the Snake Lost Its Legs by Lewis I. Held, Jr.

Ants evolved from wasps (which they still resemble) but, like fallen angels, lost their wings ~100MY ago. Ants probably lost their wings for the same reason that snakes lost their legs: these appendages became a hindrance in the tunnels which had recently become their homes. Also like snakes, living underground took its toll on their eyes, which have become mere vestiges compared to those of wasps. Presumably, as their vision waned, their chemical senses assumed a greater role to the point where modern ants are as adept as snakes in following scent trails. Wing discs still develop to some extent in larval workers, so why don't these discs go on to make wings? Until recently the evidence seemed to implicate malfunctions at various nodes of the wing gene network, but in 2010 we learned the primary reason: worker wing discs undergo programmed cell death before adulthood. We still need to figure out (1) how the cell death pathway gets triggered in workers and (2) how other castes (queens and males) manage to avoid this doom.

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