The first World War Z trailer is out, and the long-anticipated adaptation of Max Brooks’ zombie novel looks fairly cool. But it raises one important question: What’s up with all those swarming zombies?

Where are the slow-moving hordes like those in The Walking Dead or the fast-running lone rangers of 28 Days Later? What’s up with the massive throngs of quick-moving ghouls? And what’s the deal with the coordinated efforts of these things and all the body-ladder building?

Are World War Z’s raging dead actually — gulp — smart? According to zombie neuroscientist Bradley Voytek, they’re not. So Brad Pitt’s character Gerry Lane has one less thing to worry about.

“Unlike previous ‘fast zombie’ flicks like 28 Days Later wherein the zombies are basically acting independently of one another, the zombies here are showing what look like intelligent behaviors: clustering, swarming and even coming together to form a ‘zombie ladder,'” Voytek, a neuroscience Ph.D. who is on the advisory board of the Zombie Research Society, said in an e-mail to Wired. “While people might be tempted to say that the WWZ zombies are therefore somewhat intelligent, I’d argue the zombies here are simply exhibiting emergent behaviors like what we see with ants.”

The behavior, Voytek said, can be akin to those insects, which work together to take down much bigger spiders or build bridges across large bodies of water. Meaning that even though World War Z’s monsters look like they’re forming a well-coordinated army to take on Pitt and the rest of humanity, they’re actually just dumb lugs mimicking the actions of the rest of the horde.

“While these behaviors look very intelligent, they’re really a different kind of intelligence that emerges at a macro scale from micro-scale, or local, interactions,” Voytek said. “It’s like when you see a flock of birds or a school of fish all turning together: There’s not an organizing intelligence directing them all where to go; rather, each individual is tuned in to its nearest neighbors.”

Heh. Stupid zombies.

World War Z swarms theaters June 21, 2013. To find out more about zombie neuroscience, watch the animated version of Voytek and fellow zombie scientist Tim Verstynen‘s Ted-Ed zombie diagnosis in the video below.