Then, Wired tells us, comes a dinosaur egg. At least that’s one paleontological plan to flip the genetic switches separating “chicken” from “dinosaur”:
Jack Horner wants to make a dinosaur. Not from scratch—don’t be ridiculous. He says he’s going to do it by reverse-evolving a chicken. “It’s crazy,” Horner says. “But it’s also possible.”
The same basic molecular components get deployed to make the six-legged architecture of an insect or fish fins or elephant trunks. Different body shapes aren’t the result of different genes, though genetic makeup certainly plays a role in evolution. They’re the result of different uses of genes during development.
So making a chicken egg hatch a baby dinosaur should really just be an issue of erasing what evolution has done to make a chicken. “There are 25 years of developmental biology underlying the work that makes Horner’s thought experiment possible,” says [Sean] Carroll, now a molecular biologist at the University of Wisconsin-Madison. Every cell of a turkey carries the blueprints for making a tyrannosaurus, but the way the plans get read changes over time as the species evolves.
[Matthew] Harris and his colleagues soon discovered that by stimulating production of a protein called beta-catenin in chick embryos, they could get normal, nonmutants to produce neat rows of conical, crocodile-like tooth buds along their upper and lower beaks. “Chicks have the potential to create toothlike structures,” Harris says. “They just need the right signal to come through.”
Where Harris—now on the faculty at Harvard Medical School—saw an interesting bit of developmental biology, Horner saw yet another stepping stone to his dinosaur. The beta-catenin trick made growing chickenosaurus teeth relatively easy. Unfortunately for Horner, Harris is among those who don’t see the path quite as clearly. “I respect him and what he does,” Harris says. “But I think what he’s trying to sell is a little outlandish.”
The photo of the chicken with teeth should be alarming. The mention of the woolly mammoth project should be delightful.
[via Paul M Davis]