A puzzle that has baffled scientists for centuries – why some birds appear to be male on one side of the body and female on the other – has been solved by researchers.
The research, which involved studying rare naturally occurring chickens with white (male) plumage on one side and brown (female) plumage on the other, sheds new light on the sexual development of birds.
It was previously thought that sex chromosomes in birds control whether a testis or ovary forms, with sexual traits then being determined by hormones.