Joel thinks that his girlfriend is embarrassed to tell her friends that she is dating a caveman.

Nick gets a job at Norkbild, a home improvement center, through Joel. But when Nick is quickly fired for being a terrible worker, he considers his firing to be a discrimination act against him and immediately files a lawsuit against the company. Meanwhile, Andy scares a woman in an attempt to prove that he is not scary.

Joel, Nick, and Andy visit a frozen-yogurt shop, and Nick falls for the hot cavewoman who works there.

Nick takes a job as a substitute teacher and discovers that the school's mascot is an offensive, stereotypical caveman -- which leads him on a quest to have the mascot removed. Meanwhile, Andy's search for an accounting job comes to an end when Leslie hires him to balance her books. But he's torn about what to do when he discovers that Leslie has been dabbling in some creative financing for her lover that could both estrange her from her family and land.

Joel gets a new Homo Sapien friend, Jake, but Nick suspects he's a caveman trying to blend in. Also, Nick considers Jake to be a shaver, a person who shaves his body hair to differentiate himself from cavemen. Meanwhile, Thorne is attracted to the beast in Andy.

Andy has people coming at him from two different directions: Nick and Joel want him to vote their way in the next election, while Thorne wants him to buy a gun after a burglary.

Nick causes problems for Joel when his girlfriend Kate refuses to spend the night. Joel starts spending more time at her place and finds he'd rather be with his roommates. In the end, Joel moves back home and they all make compromises to get along. Andy starts working for SodaCo and his coworkers find him rather annoying. The entire office is forced to go through a series of seminars starting with "boundary training" because of him. He figures out that they can't fire him and continues to do all of the good-natured but annoying things that made everyone upset.

Nick goes to see the student health centre with paresthesia in his buttocks, where he is advised by the caveman doctor to exercise more. While there, he learns that his CRP is up but he his told not to worry. However, he does research on the internet and finds out it could be a sign of leukocytosis. worried, he pretends to be Joel and uses his insurance to see a HMO who tells him he has appendicitis and schedules him for an appendectomy. Meanwhile Joel and Kate are having relationship troubles, with Kate using far-fetched excuses not to sleep with Joel and avoiding him. Their relationship has lasted three months, which is when Kate traditionally dumps her boyfriends. Joel's boss finds out about the surgery for Nick when the insurance calls, but believes it to be for Joel and so gives him time off. When Kate comes to break it off with Joel, she learns of his major surgery and rushes to the hospital where Joel, disgusted that she only came when she thought he was having surgery breaks it off with her.

The boys are throwing a party because it is Long Night, a cavemen holiday that remembers when the cavemen did not die in the coldest day in history.

Andy participates in Nick's open mike night, and becomes famous for his character of a dumb caveman.

Joel runs into trouble when he parks in an executive's parking space. Nick competes with Maurice for the attention of his ex-girlfriend, Heather, after Maurice explains his own charm with women in terms of hunter and gatherer roles, classifying himself as a hunter and Nick as a gatherer.