At the University of Oregon, researcher Joe Thornton and his colleagues are busy "raising the dead," says Nature News' Helen Pearson. Thornton analyzes proteins that are hundreds of millions of years old in an attempt to better understand how organisms evolved. "Thornton is a leader in a movement to do for proteins what the scientists in Jurassic Park did for dinosaurs: bring ancient forms back to life, so that they can be studied in the flesh," Pearson says. He started his current line of research in 2003 when he tracked the genes for steroid hormone receptors from several living organisms back through their evolutionary trees to determine the most likely common ancestor. "Instead of stopping there, as most evolutionary biologists would have done, he then built the gene and inserted it into cells that could manufacture the ancient protein," Pearson says. Thornton tells her that the resurrection step allowed him "to experimentally test hypotheses about evolution that would otherwise be just speculation."