The Chicken, the Egg

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A new genetic experiment on chickens is helping scientists uncover clues about the bird’s evolutionary origins from dinosaurs, Live Science reported.

In their study, a research team wrote about how they were able to permanently change the scales on a chicken’s feet into feathers.

They used commercial broiler chicken embryos and specifically targeted the sonic hedgehog gene (Shh), which is responsible for the development of certain characteristics at the embryonic level.

The gene – named after the video game character – affects the development of fundamental parts, such as the spinal cord, limbs, and brain, but also scales and plumage.

Researchers then utilized a technique called “egg candling” to illuminate the blood vessels inside an egg using a light source. This allowed them to detect the suitable vessel to inject a molecule to trigger the activation of the Shh pathway into the developing embryo.

The newborn chicks displayed downy soft feathers on their feet that were comparable to the plumage covering the rest of their bodies, the team noted.

“The effect is really clear once they hatch,” said lead author Rory Cooper. “And the change lasts. Once the chickens develop the feathers, they don’t go back to having scales on the targeted area.”

Cooper and his colleagues noted that the findings could help scientists understand how the avian species evolved.

“In dinosaurs, feathers could have been used to regulate the animal’s internal temperature or as a colorful display,” said co-author Michel Milinkovitch. “By changing the expression of one gene, we were able to create a cascade of developmental effects that triggered feather growth, offering new insights into the evolution of these animals.”