In Mr. Jakoby's original story, as in the finished movie, a meteor strikes Earth, carrying a sampling of one-cell alien life forms that rapidly evolve into more dangerous creatures. But his story was more of a flat-out thriller about top scientists. Until Ivan Reitman read it and understood it. Mr. Jakoby took a swing at a comic version of the script, but Mr. Reitman wanted even more laughs and brought in another team of writers, David Diamond and David Weissman, who shifted the heroes from Ivy League titans to community college burnouts. That's the way the business works.
Directors usually bring in their own writers.
And I have to admit, they did make a funny movie out of it. Privacy Information Stay connected to the news that interests you with free e-mail alerts from The New York Times.