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The science of zombies
University of Alaska Southeast Assistant Professor of Science Matthew Pawlus talks to a crowd about zombies Wednesday at the UAS Ketchikan Campus Library. Staff photo by Taylor Balkom

Daily News Staff Writer

It’s possible that cat owners who attended Wednesday’s Ask UAS lecture might have given their feline friend a worrisome look when they arrived home.

As a part of the Ask UAS series, University of Alaska Southeast Assistant Professor of Science Matthew Pawlus gave a presentation on zombification and parasites — and spoke about one parasite in particular that can be found in cats, called toxoplasma gondii, or toxo.

“He (the parasite) does much of his life in cats, but every so often his eggs find their way into a mouse,” Pawlus said to a crowd in the UAS Ketchikan Campus Library. “That’s a problem, because he really likes cats. He’s a cat person — or cat parasite, I suppose.”

If toxo finds its way into a mouse, it works its way into the brain and messes with the brain chemistry of the rodent. Pawlus said it causes the mouse to be attracted to cat urine, instead of being afraid of it.

“This causes the mouse of course to seek out areas where there’s lots of cats, and get eaten by a cat,” he said.

Once that happens, the parasite will fulfill its life in a cat and continue the circle of life. He said this is evidence that a single-celled protist is able to control the behavior of something as complex as a mammal — and mice are similar to humans. Pawlus said we share about 95 percent of our genes with mice.

Can the parasite work its way into humans? Pawlus said it can indeed.

“If you have cats, and you’re changing a litter box, that’s something to think about,” he said, as people in the room turned towards their friends and gave each other skeptical looks. “Wash your hands afterwards.”

He said toxo can have some effects on a human brain behavior — such as cognitive defects. Pawlus said toxo in humans is also associated with increased vehicular accidents and neurological disorders.

“Next time you’re in a vehicle accident, maybe think about getting a brain biopsy and searching for toxoplasma, you might be able to sue somebody, maybe a kitty litter company,” Pawlus said as the group let out a few laughs.

Pawlus added there is a correlation between people with schizophrenia and bipolar disorder, and people who are infected with toxo in their brain. Among humans, he said it’s estimated that there’s a 30 to 60 percent chance that humans actually have toxoplasma in the brain, and they don’t even know it.

“The scary part about this one is we deal with cats on a regular basis,” he said, “and these eggs are being spread by cats.”

He said if the group were to look around the room, there’s a good chance that at least one person in the room, but probably more, already has the parasite inside of them.

Toxoplasma was a part of the last group of possible zombies Pawlus talked about — pathological zombies and parasites. He said it’s the “most exciting” category of possible zombie pathogens, because there are a lot of them.

He said people tend to think of parasitism as a strange thing, because humans are not parasites — but really, parasitism is the most common form of life on the plant. Pawlus said close to about three-quarters of life on the planet exists as a parasite, living inside or on top of something else.

“We tend to ignore parasites in day-to-day life unless they make us sick,” he said. “Most parasites are going to make you sick, cause some type of disorder. However, there’s a lot of research suggesting that parasites can actually be used for some sort of medical treatments. They might actually help you out.”

When people think about zombie parasites, Pawlus said people are speaking of parasites that can change the brain function of a host — and he said there’s evidence of it happening almost everywhere that we look.

A popular zombie parasite is an ant fungus called cordyceps — a fungus and parasite that controls the brain function of ants, who have a “fairly simple brain,” but a functional brain, nonetheless.

Cordyceps doesn’t just cannibalize the ant — before the fungus springs forth from the ant's head and uses the ant for nutrients, the fungus actually controls the ants brain. Pawlus said the fungus causes the ant to leave its colony, and climb up to a height of about 25 centimeters off the ground.

“Once it gets that high, it’s in basically the optimal range for growing cordyceps fungus — it’s just the right humidity,” Pawlus said.

The ant then latches onto a plant and then it dies. Then, the cordyceps erupts from its body. Pawlus showed a video of it happening, and the ant’s friend actually dragging it away from the colony so it doesn’t infect and kill off the group.

“There’s his friend carrying him off,” Pawlus said, captioning the video. “Kicking him to the curb.”

Before Pawlus talked about pathological zombies, he spoke about psychological and pharmacological zombies. He mentioned several different types of worms, mad cow disease, bath salts and several other examples of possible zombies.

He ended his lecture by saying it’s not bad to be afraid of zombies.

“If you showed up at this talk because you have an interest in zombies, and you ended up learning one or two things today that you can drop at parties, that’s great,” Pawlus said.

“I just want to encourage you all, whatever you’re interested in, whether it’s zombies or not — keep following that interest,” he added. “It will lead you (to) weird places. You may end up giving a talk up here one of these days.”