Negroni argues that in the world of “Monsters Inc.”, humans no longer exist in the current timeline. It posits that “Monsters Inc.” takes place somewhere between 3100 and 5201, during a time when humans died out because animals eventually evolved beyond them. We see what might be another example of this period in the movie “Onward,” which depicts a world of magical creatures living in human-like societies where humans themselves don’t exist. “Onward” may represent a transition period in this evolutionary phase.

But, you might ask, there are humans in “Monsters Inc.”, so how does it work? The answer, dear reader, is time travel.

Although humans no longer exist, monsters (which evolved from animals) still need human emotions to create power. Monsters Inc. is thus created to collect the emotion of a previous timeline in which humans still existed. The doors depicted in “Monsters Inc.” are portals that can send Monsters Inc. employees to the past, where they then scare children and harvest their power. To maintain their current schedule and keep the secret from leaking out, the company kept this technology a secret, convincing all of the monsters that their employees are visiting another world – one the company claims is highly toxic.