Half-Male, Half-Female Chicken Mystery Solved

It was a tough egg to crack, but scientists have discovered that half-male, half-female chickens possess a mixture of genetically male and female cells.

It was a tough egg to crack, but scientists have finally explained why some chickens are born half male and half female.

The bodies of these hen-rooster hybrids, or gynandromorphs, have a mixture of genetically male and female cells, the research reveals.

Only about 1 in 10,000 chickens are born as gynandromorphs, which have male features—such as a rooster's comb and a defensive leg spur—on one side of their bodies and dainty, henlike features on the other.

Researchers had thought a rare genetic abnormality causes the condition. To test this theory, Michael Clinton of the University of Edinburgh and his team analyzed cells from three gynandromorph chickens.

(Related picture: "Lobster Caught

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