What's behind the runs on toilet paper?

(FOX 2) - What are the hottest brands out there this season? Well, they're not Gucci, Jordan or Apple. The in-demand brand names are Charmin, Cottonelle and Northern ... toilet paper. 

It's a necessity but who would have predicted toilet paper would be sold out just about everywhere? I understand the demand for masks and hand sanitizer - this is the coronavirus we are fighting.  But why does everyone want toilet paper?"

Dr. Stephanie Preston is a professor of psychology at University of Michigan. She says part of it has to do with social cues.

"(They are saying) 'Everybody is buying toilet paper, I better buy toilet paper too.'"

And while that may explain the panic buying at the start of the hysteria, why a month or so in are the shelves still bare in the bathroom tissue aisle?

"Supply chains which are good at managing and reducing costs, are horrendous at being responsive," said Dr. Steven A. Melnyk.

Melnyk is a professor of operations and supply chain management at Michigan State University.

He says companies that make just about anything here in America are based on keeping costs down and prices down for their customers, which means making just enough product to fill the shelves.

"Now you have a system that is very good at dealing with predictability and now what you're asking it to do is to is to deal with uncertainty," he said.

And that uncertainty has lead people to keep buying toilet paper anytime they see it - which may seem weird but psychologically isn't.

"There's a lot of negativity toward the word hoarding or stockpiling," Preston said. "People are using it as an accusation, as a judgment against somebody. But it's perfectly normal and adaptive in evolution for hundreds of millions of years and lots of species do it."

It's an animal instinct to hoard when you're overcome with anxiety. But the computerized, digital world of big company sales perhaps doesn't understand "human nature."

"Everything has been so predictable so these companies can use all this data they've been gathering for years to know how much to produce and now this throws a monkey wrench into everything," Melnyk said. "And their systems were not designed to deal with it."

So the companies that produce toilet paper are reprogramming to keep up with demand. But right now, the demand isn't being driven by need, it's being driven by human emotions - the emotion to grab and hoard the rolls of white gold.

"These are all normal behaviors and I don't think it's necessary to demonize anybody for doing it," Preston said.

So until we flush out this virus - it's likely the toilet paper shelves will be wiped out.