What stops a chick’s penis from growing while allowing a duck’s to reach startling lengths?
How did the chicken lose its penis? By killing off the growing appendage in the egg.
That’s the finding of a new study, which reveals how most birds evolved to lose their external genitalia. Turns out, a particular protein released during the development of chickens, quail and most other birds nips penis development in the bud, according to the new research, published today (June 6) in the journal Current Biology.
The findings have implications for genital development in general, which is important because birth defects in the external genitalia are among the most common congenital defects in humans, said study researcher Martin Cohn, a developmental biologist at the Howard Hughes Medical Institute and the University of Florida.
“Comparative evolutionary studies of development allow us to understand not only how evolution works, but also gives us new insights into the possible causes of malformations,” Cohn told LiveScience.
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