Silkie the "SHH" gene, called the ZPA Regulatory Sequence (ZRS). This causes ectopic "SHH" expression in the anterior of the developing limb bud, leading to increased tissue growth and digits. While the feet of the Silkie display polydactyly, the wings have the standard tridactyly (three digit) arrangement. The Japanese Silkie initially develops additional digits in the wing as an embryo, but these are lost prior to hatching. The genetic cause behind Silkie polydactyly differs from those that cause polydactyly in the Dorking chicken breed, which is due to ectopic "FGF4" expression in the AER, with ectopic "SHH" a secondary effect. The
The Great Silkie of Sule Skerry as "Silkie" in the early 1960s. Although Jean Redpath disparaged Water's tune as "phony", preferring a longer version of Child 113 to another tune, by 1965, Jim Butler had heard Waters' tune sung by a Scottish student at the University of British Columbia, unaccompanied in the traditional style, and under the impression that he had learned it from his grandfather. "This has to be one of the most flattering things that has ever happened to me", added Waters, who eventually copyrighted his version and assigned it to Folk Legacy Records. Folk Legacy reassigned all copyright interest to James Waters in