The plot of the film follows college professor Ira Kane (David Duchovny) and geologist Harry Block (Orlando Jones) who investigate a meteor crash in Arizona. They discover that the meteor is harboring extraterrestrial life which is evolving very quickly into large, diverse and outlandish creatures.
Evolution was based on a story by Don Jakoby, who converted it into a screenplay along with David Diamond and David Weissman. The movie was originally written as a serious horror science fiction film, until director Ivan Reitman re-wrote much of the script. Shooting took place in California with an $80 million budget and the film was released in the United States on July 13, 2001. The movie grossed $98,376,292 internationally. Reviews for the film were mostly unfavorable, as the movie review aggregation website Rotten Tomatoes gave the film a 43% positive rating.
A short-lived animated series, Alienators: Evolution Continues, loosely based on the film, was broadcast months after the movie was released.
Wayne Grey (Seann William Scott), a fireman trainee practicing in a shack in the desert near Glen Canyon, Arizona, sees a meteor strike his car and land in an underground cavern. College professor Ira Kane (David Duchovny) and his colleague, geologyprofessor Harry Block (Orlando Jones), investigate, taking a sample of strange blue liquid that oozes from it. Ira discovers that it harbors extraterrestrial single-celled nitrogen-based organisms multiplying exponentially, condensing millions of years of evolutionwithin a matter of hours. The next day, they take the science class to survey the meteor site and find it already surrounded by evolved oxygen-converting fungi and alien flatworms, later discovering the cells and organisms reproduce rapidly through mitosis.
Soon Ira and Harry find the site sealed off by the Army, who have set up a base. They take General Russell Woodman (Ted Levine) and the clumsy Dr. Allison Reed (Julianne Moore) to court for the right to be part of the research of their discovery, but their efforts fail when it is brought up that Ira was previously discharged from the army after creating an anthrax vaccine which led to terrible physical disorders, dubbed "The Kane Madness". When Woodman confiscates their research, Ira and Harry infiltrate the base underground to get another sample and find an alien rainforest teeming with life. They are caught by Allison as an alien insect gets inside Harry's body, which has to be removed rectally by a doctor, and immediately dies.
Wayne arrives at the college and shows the two the dead body of an amphibian alien which killed a country club owner, while another creature appeared in a woman's home before dying. Ira and Harry theorize the aliens are spreading through the caves connected to the main cavern but cannot breathe oxygen. The trio later find a valley from the caves strewn with dead flying dinosaur-like creatures, one of which gives birth before it dies. The newborn alien is able to breath the oxygen safely and flies away to a mall, where it snatches up a shoplifter before the trio gun it down.
The Governor of Arizona (Dan Aykroyd) demands to know what is happening. Allison explains that in two months the aliens will spread and multiply enough to engulf the entire United States. Woodman proposes a plan to evacuate the area and use napalm to burn the aliens away, when Ira, Harry and Wayne arrive to tell them about their findings. The aliens, now evolved into primate-like creatures, climb up from the caves below and attack them, but are fought off. The shaken governor then approves Woodman's plan against protests from Ira and Allison that they don't know how the aliens will react. Allison leaves the site, procuring Ira's original research and samples of the blue liquid for him.
At the college, Harry accidentally tosses a match into the petri dish of alien liquid, causing a mass of flesh to rapidly grow from it. Ira realizes that heat is the catalyst to their evolution, as it activated the dormant alien cells when the meteor entered the atmosphere. They attempt to warn Woodman that the effects of napalm will be disastrous, but are rebuffed. Looking at the positions of nitrogen and carbon on the periodic table, Ira theorizes that selenium might be poisonous to the aliens, since they are nitrogen-based, asarsenic is poisonous to Earth's carbon life. Ira's students Deke and Danny (Ethan Suplee and Michael Ray Bower) recall that selenium sulfide is the active ingredient in Head & Shoulders shampoo, so the team procures a firetruck and fills it with the shampoo.
Woodman begins the napalm strike, causing the aliens to rapidly mutate and merge into a gargantuan amoeba-like organism that bulges out of the caves. As it prepares to divide via mitosis, the team drives under the organism and pumps a firehose of shampoo into its rectal hole, causing it to explode. Governor Lewis declares Ira, Harry, Wayne and Allison heroes, making Wayne an honorary firefighter while Ira and Allison skip the festivities for romance in the fire truck. Later, Harry, Ira and Wayne promote Head & Shoulders for both hair care and fighting aliens.
The three-eyed smiley face used as the logo of the film in marketing was borrowed from the comic book Transmetropolitan. Producers had to get permission from DC Comics to use it and were licensed by Smileyworld Ltd., owner of the smiley face trademark, to use it for advertising and commercial purposes.
During the lengthy shooting in Page, Arizona, Dan Aykroyd entertained locals by checking ID cards for guests at a bar, greeting people at Wal-Mart, and visiting locals for a cup of coffee in their homes. Because the film was shot (but not set) in December, DreamWorks asked the locals to delay putting up their Christmas decorations. Following the shoot, DreamWorks paid the city employees overtime to decorate the town in time for Christmas.
All of the on-campus, classroom, lab and professor's office scenes were filmed at California State University, Fullerton, in Fullerton, California. The building used for the movie was Miles D. McCarthy Hall, which is home to the College of Natural Science and Mathematics.
The clumsiness of Julianne Moore's character was her idea. The three main male characters perform a commercial for Head & Shoulders at the end of the movie; Ivan Reitman's son Jason came up with the idea. As part of the commercial they each hold out a bottle of Head & Shoulders. Harry Block (Orlando Jones) holds his out backwards.
- David Duchovny as Colonel (Ret.) Dr. Ira Kane, PhD.
- Julianne Moore as Dr. Allison Reed, PhD.
- Orlando Jones as Professor and Coach (female volleyball) Harry Phineas Block
- Seann William Scott as Wayne Grey
- Ted Levine as Brigadier General Russell Woodman
- Ethan Suplee as Deke Donald
- Michael Bower as Danny Donald
- Pat Kilbane as Officer Sam Johnson
- Ty Burrell as Colonel Flemming
- Dan Aykroyd as Governor Lewis
- Katharine Towne as Nadine
- Gregory Itzin as Barry Cartwright
- Ashley Clark as Lieutenant Cryer
- Stephanie Hodge as Jill Mason