Host Ira Glass reminds the audience about the old TV series MacGyver, about the guy who stops bad guys without a gun. He uses science and sheer ingenuity to invent solutions.

You can divide all living creatures into two camps. We humans are in one camp, along with lots of other things like dogs and birds and trees and caterpillars.

Susan Drury reports from Tennessee on a test that provides sudden truth from a stranger. It's based on a science whose goals could not be grander—to aid in the fight between good and evil.

Producer Alex Blumberg explains that he wanted to do this show because of his conflicted relationship with his own testosterone. He tells host Ira Glass that the reasons go back to a girl in his eighth-grade homeroom and the 1970s seminal feminist novel The Women's Room. We also hear from a man who stopped producing testosterone due to a medical treatment and found that his entire personality was altered.

We hear two stories of everyday life which are more easily understood if one knows some of the laws of physics, specifically the Mediocrity Principle and the Casimir Effect.

More stories like the one in the prologue, where kids look at something going on around them, observe it carefully, think about it logically, and come to conclusions that are completely incorrect. Includes a story set at Christmastime, where a father tells his daughter about the baby Jesus being born, and all the "good stuff." Then the daughter notices a picture of Jesus on the cross, and asks why they killed him.

Host Ira Glass tells the story of a time capsule project designed to document our lives so that people a thousand years from now can know what we were like. Ira explains that when a friend of his got involved in the time capsule, Ira realized that he hates the people of the future.

Keith Gessen, a young Russian emigre, revisits the heroes of his youth: the brave Soviet dissidents who risked their lives at the height of the Cold War. Many of them resettled into comfortable suburban lives in America.

Producer Nancy Updike tells the story of scientists who simply made up an invisible, weightless subatomic particle called the neutrino. Then they set out on the task of finding it, using tools that sound positively crude: A mineshaft and 100,000 gallons of dry cleaning fluid.

D. Travers Scott and his boyfriend spent six months gathering data on their own relationship and put together a report on it in the form of a corporate annual report.

Scott Carrier in Salt Lake City with the latest installment in his 12-year quest to chase down and catch an antelope. This story and others are included in his book Running After Antelope.

Ira interviews Bob Helms, creator of the zine Guinea Pig Zero, which is about people who make their living by donating their bodies to science for medical experiments. Bob says he wouldn't do spinal tap studies or psychoactive drugs (he calls the people who do the latter "brain sluts").

Anthropologists agree that humans stopped being animals when they started walking upright, on two legs. But scientists don't agree on why our ancestors did this.

Writer Jack Hitt discovers that the world of dinosaurs is a man-made creation, a simulated world that may or may not accurately reflect what happened on earth 100 million years ago. Talking with dinosaur experts like Jack Horner (whose work was the basis of much of the film Jurassic Park), Hitt finds that most of what you think you know about dinosaurs is probably wrong, and that Americans' ideas about dinosaurs go through "fashions" that reflect the national mood: We believed dinosaurs were more aggressive when we were on the brink of World Wars One and Two.

This American Life contributor Paul Tough visits Catherine Chalmers. She raises small animals and insects in her apartment, feeds them to each other, and photographs them eating each other.