"Uppsala University functional genomicist Leif Andersson and colleagues used cutting-edge sequencing technology to comb the chicken genome and identified some genetic signatures of domestication, according to a study published today (10th March) on Nature's website. These genetic signatures code for traits that make domestic chickens useful as egg or meat producers, but in humans, changes to homologous genes can lead to complex 'lifestyle diseases' -- such as obesity and diabetes. This suggests that biomedical researchers may be able to use the domesticated chicken to research these conditions."
The other, in Nature, No Sexual Confusion for Chicken Cells, takes note of a phenomenon, gynandromorphism, in which both sexes are expressed in a single individual, http://tinyurl.com/yd36lmy. It's described as a "rare, naturally-occuring phenomenon in which one side of the animal appears male and the other female." How this happens is being explored for insight into how sex is determined, the influence of hormones and the inherent sex of the animal's cells.
"The cluster of seemingly nondescript cells that grows into a chick has a stronger sense of identity than you'd think. Rather than waiting for hormonal cues from the sex organs, the cells know whether they're male or female from the start, a new study reveals. The discovery challenges the standard picture of how sexual differences develop in vertebrates."
This photo shows such a bird in a mirror, but I'm not sure what breed they are. Perhaps some variety of Leghorn. Although the researchers say this occurs naturally, I've never heard of it. It would certainly be obvious in breeds that have significant sexual dimorphism, such as Faverolles and Dorkings. On the other hand, in breeds that are henny feathered, such as Campines, the birds wouldn't look much different from usual.