Digital SAT Reading and Writing Practice Question #634

In evolutionary biology, the "Red Queen Hypothesis" posits that species must constantly adapt and evolve not merely to gain a reproductive advantage, but simply to survive against ever-evolving opposing species. Consider a predator-prey dynamic between foxes and rabbits: if rabbits evolve longer legs to run faster, foxes must inevitably evolve stronger cardiovascular systems or better stealth to avoid starvation. However, paleontological records of the extinct dire wolf and its primary prey, the giant ground sloth, reveal a period of roughly one million years during which neither species underwent significant morphological changes. During this epoch, the local environment remained remarkably climatically stable, and no new predatory or competitive species migrated into the region.