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Delve deeper into hot topics featured in NGM's September Geographica and Who Knew? and Field Dispatch with help from Resources. Click on a link, pick up a periodical, browse through a book, and explore!
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There's a buzz about stick insects: Scientists now believe they've lost and regrown their wings several times during their 300-million-year history, shattering the long-held assumption that the insect wing evolved just once. Camouflage artists that mimic twigs, walkingsticks are divided into two types: winged and partly winged or wingless. Michael F. Whiting, a biologist at Brigham Young University, analyzed DNA from 37 species and found that their flightless ancestors sprouted wings about 250 million years ago. "After that, walkingsticks lost their wings, then re-evolved them at least four times," Whiting says. But the wings didn't re-evolve from scratch. Genes that govern walkingstick wing development appear to be linked to genes for other—more crucial—body parts, perhaps legs. So the wing genes are never lost, even if they aren't physically expressed. The genes turn on or off, depending on whether conditions make it more advantageous to be winged or wingless.
—John L. Eliot
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