1. In the 1950’s, and the 1960’s the biologist Edgar Zwilling experimented on chicken embryos by cutting small pieces off of the bird, and either keeping them removed, or moving the piece to another part of the embryo. One experiment took off the tip of the embryos developing wing, which completely stopped the wing from forming. This discovery was the discovery of the ZPA, which led to the discovery of the hedgehog gene, which allowed scientists to discover the gene in all developing animals.
2. The Hedgehog gene is a gene found in the center of flies. It was named the Hedgehog gene due to its resemblance to a hedgehog, and is used to determine which side will be the front of the fly, and which side will be the back of the