Which came first, the chicken or the dinosaur?
An easy question to answer you might think, but the answer may be about to change, as an evolutionary biologist at Harvard University has developed snouted chickens.
Chickens share a common ancestor with alligators. The tip of an alligator snout is made of a separate set of paired bones called the premaxillary, while in birds, these have fused with the main bone of the upper jaw to form one single, sharp bone. Arhat Abzhanov started by trying to pinpoint the gene changes that led to the myriad beak shapes of Galapagos finches. In 2004, he showed that all the finches share a handful of genes crucial to beak development, but instructions for the signaling molecules they control vary from bird to bird. Abzhanov realized that a similar process might underlie the much bigger evolutionary shift from snouts to beaks.
Abzhanov scanned signaling molecules in alligator and chick embryos and found that that the two of them – known as sonic hedgehog and fibroblast growth factor 8 – show up before the snout and beak form. In alligators, however, the molecules were only present along the sides of the face. Chicks express them both at the sides and centre of the developing face. What would happen, he wondered, if he turned that central expression off?
He developed a gel bead full of proteins that stick to the signaling molecules and deactivate them. As the molecules arrived at the centre of the embryonic chick face – around day five – Abzhanov added his bead to the mix and the chicks developed paired bones. “It looks exactly like a snout looks in an alligator (at this stage)” says Abzhanov.
In the long term, reports New Scientist, Abzhanov dreams of turning chickens back into Maniraptora – small dinosaurs thought to have given rise to the 10,000 species of birds that exist today.
The snounted chicks have not been allowed to hatch, but the work suggests that a variety of traits could be introduced, or reintroduced to whatever the creature that emerges from an egg would be called. While chickens with ostrich-length legs or peacock-type breasts may belong in realm of story books, Abzhanov’s work and similar could become increasingly important given expected pressures resulting from a growing population and finite resources.
Chickens with alligator beaks conjure up images of Jurrasic Park for me, and I don’t fancy them hatching and roaming the streets, but who knows the benefits that this sort of work may eventually lead to?
