Classroom Evolution Kids Can Watch
Evolution has taken another step away from being dismissed as “a theory” in the classroom, thanks to a new paper published this week in the online open-access journal PLoS Biology. The research article, by Brian Paegel and Gerald Joyce of The Scripps Research Institute, California, documents the automation of evolution: they have produced a computer-controlled system that can drive the evolution of improved RNA enzymes—biological catalysts—without human input. In the future, this “evolution-machine” could feature in the classroom as well as the lab, allowing students to watch evolution happen in their biology lessons.
The evolution of molecules via scientific experiment is not new. The first RNA enzymes to be “evolved” in the lab were generated in the 1990s. But what is exciting about this work is that the process has been made automatic. Thus evolution is directed by a machine without requiring human intervention-other then providing the initial ingredients and switching the machine on.
As all students of Darwin know, evolution occurs when there is variation in a population; where some variants confer a survival or reproductive advantage to the individual, and where the basis for this advantage can be inherited. Finally, there must be a selection pressure—a reason that not all animals can survive or reproduce—such as a limited supply of food or a predator that must be avoided. These are the principles that the Paegel/Joyce system uses. The system begins with a population of RNA enzymes, which are the individuals that will evolve, and these enzymes vary slightly from each other. The enzymes are challenged to catalyse a reaction, and those that do catalyse it bind a “promoter” sequence to themselves in the process. Other enzymes in the machine (which act like part of the machine, rather than part of the experiment) cause any RNA enzyme bound to a promoter to be reproduced; therefore, enzymes that are good at reacting with the substrate become more numerous. This is analogous to those animals that are most successful being able to reproduce, both of which lead to the advantageous variation becoming more common.
It’s kind of hard to dismiss evolution as a "theory" when it’s happening right in front of your eyes.