Blinking twice at Carl Zimmer

July 1, 2009

I have to thank Carl Zimmer, science writer extraordinaire, for restoring a bit of my sense of wonder in science, and in our mutual profession. His much-emailed NYTimes two-pager about firefly mating practices is, as Charlie Petit might have said, a simple story, elegantly told.

My sentimental turn happened right about here:

In recent years scientists have analyzed the DNA of fireflies to figure out how their light has evolved. The common ancestor of today’s fireflies probably produced light only when they were larvae. All firefly larvae still glow today, as a warning to would-be predators. The larvae produce bitter chemicals that make them an unpleasant meal.

I guess it was remembering how beautiful evolution is. It was also really cute when he described how the researcher clicked her penlight twice and and got a firefly to flash back. Picking up:

As adults, the earliest fireflies probably communicated with chemical signals, the way some firefly species do today. Only much later did some firefly species gain through evolution the ability to make light as adults. Instead of a warning, the light became a mating call. (An enzyme in the firefly’s tail drives a chemical reaction that makes light.)

The more Dr. Lewis watched firefly courtship, the clearer it became that the females were carefully choosing mates. They start dialogues with up to 10 males in a single evening and cankeep several conversations going at once. But a female mates with only one male, typically the one she has responded to the most.

It may have something to do with advertising a male’s “nuptial gift” of protein, injected along with the sperm, which sustains the female during reproduction.

For more firefly science, read Steven Strogatz.


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