AMC threw The Walking Dead fans for a loop at this year’s San Diego Comic-Con with a brief tease of alleged “smart” zombies in a new trailer for the last eight episodes of the eleventh and final season. “I’ve heard stories of walkers that can climb walls and open doors,” says Aaron (Ross Marquand). “I was never sure if they were just stories…” You might think the hordes of the undead are somehow evolving after all these years, but you’d be wrong. In fact, these resourceful ghouls have been around since the very start.

“We’ve seen that on the show before,” Walking Dead brand manager and executive producer Scott M. Gimple stated during an interview with Entertainment Weekly. “It has escaped discussion on the show. You can see in the trailer, there’s some different behavior, but this isn’t any sort of reinvention. It’s addressing something that is inside the show already. The calls are coming from inside the house.”

Showrunner and executive producer Angela Kang echoed that sentiment, adding that these brainy (no pun intended) walkers “will cause some massive problems for our people.”

Longtime audiences may recall how Morgan’s wife not only returned to the house in which her husband and son were hiding long after she succumbed to the zombie virus there, but also had the wherewithal to turn the doorknob. In the very next episode, you can clearly see a Walker using a rock to try and break into the Atlanta department store where Rick, Andrea, Glenn, T-Dog, and the other survivors have posted up.

“That came right out of Night of The Living Dead. That was right out of Barbara in the car with the first-ever zombie, Bill Hinzman, using a rock,” said executive producer and director Greg Nicotero, who started work on the show as the lead visual and makeup effects artist. “The truth is we hadn’t really figured out yet what the rules for the zombies were,” he admitted. “They were also a bit faster in the first episode when they chased Rick down the street on his horse.”

To get around the absence of “smart” zombies after more than a decade, the creative minds came up with a retroactive explanation that leans into the ways in which certain creatures adapt to the environments in which they live. “We sort of played into that as if there might be certain walkers in certain regions that might have different abilities that we really haven’t seen before,” Nicotero said. “We’re kind of playing into the idea that some of these are out there and they’re just encountering them now.”