The rock pocket mouse is a living example of Darwin's process of natural selection. Not only is evolution happening right now everywhere around us, but adaptive changes can occur in a population with remarkable speed. This speed is essential if you're a desert mouse living in an environment where a volcanic eruption can reverse selective pressure in nearly an instant. The film features Dr. Michael Nachman, whose work in the field and in the lab has quantified the selective pressure of predators and identified the genes involved in adaptation. In a complete story, from ecosystem to molecules, pocket mice show us how random changes in the genome can take many paths to the same adaptation—a colored coat that hides them from predators.

For life to survive, it must adapt and readapt to an ever-changing Earth. The discovery of the Antarctic icefish has provided a stunning example of adaptation in an environment both hostile and abundant, where the birth of new genes and the death of old ones have played crucial roles. Researchers Bill Detrich, Christina Cheng, and Art DeVries have pinpointed the genetic changes that enable icefish to thrive without hemoglobin and red blood cells and to avoid freezing in the icy ocean.

In some parts of the world, there is an intimate connection between the infectious parasitic disease malaria and the genetic disease sickle cell anemia. A keenly observant young man named Tony Allison, working in East Africa in the 1950s, first noticed the connection and assembled the pieces of the puzzle. His story stands as the first and one of the best understood examples of natural selection, where the selective agent, adaptive mutation, and molecule involved are known—and this is in humans to boot. The protection against malaria by the sickle-cell mutation shows how evolution does not necessarily result in the best solution imaginable but proceeds by whatever means are available.