Where Did The Pigeon Get That Weird Thing On Its Head?

pigeons

Visit most any city on Earth, and you’ll find flocks of pigeons. And as you stare at the birds as you sip a cup of coffee at a sidewalk cafe, you may be fascinated by their diversity: varying in color, from white to grey to black to brown. Even the common grey ones all look a little different.

But true pigeon variety is really found in the 350 or so fancy breeds that have been developed since the bird was first domesticated 5,000 years ago. (Above, clockwise from upper left: English trumpeter, Brunner pouter, fantail, Italian owl, Chinese owl, Pomeranian pouter.)

One of the traits that can make a pigeon look extraordinary is the presence of a head crest. This headgear itself can come in a variety of looks, but scientists who have sequenced the genome of Columba livia (that’s the common rock pigeon) have found that “crest” or “no crest” is determined by a single gene, called EphB2.

The trait first becomes apparent when the birds are juveniles, but the mutant gene has effects even earlier in life: When the pigeon embryo is still in the egg, the gene causes molecular changes that reverse the direction of growth of the feathers on the top of the head.

The study was published online last week by the journal Science.

Images courtesy of Mike Shapiro, Science magazine

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