Double-Sex Chickens Wow Scottish Scientists

The secret genders of chickens revealed. (Tim Archibald /The Image Bank/Getty Images)

Forgive the exploitative (and awesome) headline, but it's Friday and I feel like we all might need a good scientific tidbit to carry with us to our various dinner parties, hot dates, family meals or Xbox Live gaming sessions. Live your life how you see fit, people, just make sure you talk about gender-bending chickens.

As covered by NPR (and published in Nature), Michael Clinton of the University of Edinburgh studies these amazing chickens, which are known in sciencey circles as "gynandromorphs." I kid you not: they're split right down the middle. One side looks like a rooster; the other side like a hen. Seriously, look at the photo.

It's like some sort of kooky fashion show costume. Except, as Clinton points out, its rooted at the cellular level. Contrary to his initial suspicions, the condition is not due to hormones. The gynandromorphs have both male and female cells, each containing either male or female chromosomes. Normally, one set of these chromosomes determines what kind of gonads a creature has: testes or ovaries.

Scientists still aren't sure what exactly causes this anomaly. Sex is imposed by both external hormonal signals and internal genomic signals. But up until now, scientists assumed that in birds and mammals hormones were the key signal for sex determination.

The research continues. Until then, I think you have some double-gender chicken jokes to work on.

About the Author: Robert Lamb spent his childhood reading books and staring into the woods — first in Newfoundland, Canada and then in rural Tennessee. There was also a long stretch in which he was terrified of alien abduction. He earned a degree in creative writing. He taught high school and then attended journalism school. He wrote for the smallest of small-town newspapers before finally becoming a full-time science writer and podcaster. He’s currently a senior writer at HowStuffWorks and has co-hosted the science podcast Stuff to Blow Your Mind since its inception in 2010. In his spare time, he enjoys traveling with his wife Bonnie, discussing dinosaurs with his son Bastian and crafting the occasional work of fiction.