Why did the chicken grow a beard?

June 10, 2016

Beards have made their comeback not only in the hipster population but also for some chickens in the form of tufts of elongated feathers around their face and beak. For years, farmers have noticed these bearded chickens, but the cause has always been a mystery. Now, thanks to scientists in China, the mystery has been solved.

In their study, scientists compared the DNA of bearded chickens to non-bearded chickens and their results led them to investigate a gene, HOXB8. They found that bearded chickens have multiple copies of HOXB8 and surrounding genes, while non-bearded chickens only had one copy of HOXB8.

After they found the gene duplication, the scientists wanted to know about the activity, also known as gene expression, of HOXB8. A recent article on the study compares gene expression to the volume control on a radio dial. The gene can be turned up, blasting loudly, or played at barely a whisper. The scientists took skin samples from around the faces of chickens to determine whether the HOXB8 gene was being "turned up" more in bearded chickens than in normal chickens.

In chickens of all ages tested, the HOXB8 gene was highly expressed in the facial skin of bearded chickens, but not on at all in the facial skin of non-bearded chickens. In other words, the gene was being played loudly in the bearded chickens, but was silent in the non-bearded ones.

As of now, the article explains that the scientists don't believe that beards provide the chickens with any evolutionary advantage. Although the researchers can only speculate why these genetic differences came about, they are most likely due to thousands of years of domestication and breeding practices. In fact, some breeders specifically select bearded birds over their non-bearded or “normal” counterpart.

Ying Guo, one of the study's authors and a geneticist at the China Agricultural University, said the scientists really have no knowledge of the exact time when the breads were first formed. But he said he believes it holds hundreds of years of history.

In other words, chickens have probably been growing beards long before it was cool.

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