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Can chickens really change gender? ©iStock

Can chickens really change gender?

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Cocka-doodle-woahhhhhh....

Asked by: William Spurr, Colchester

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It depends on how you define gender. The chromosomes that normally control the physical differences between male and female are fixed at the moment of fertilisation and cannot change. But the sex chromosomes work by coding for enzymes that affect the bird’s development in the egg and during its life. These enzymes are sensitive to temperature and if eggs fertilised with male chromosomes are cooled by a few degrees for three days after laying, the relative activity of the sex hormones will favour development of female characteristics. (In reptiles, temperature is entirely responsible for determining sex.) In about 10 per cent of cases, this cooling will produce a chicken with a fully functioning and reproductively fertile female body-type; even though the chicken is genetically male.


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Authors

luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.

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