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Scientific American Instant Egghead
Zombies don't just exist in science fiction movies and music videos.
They're for real and we can find them all over the animal kingdom.
It's not because animals have come back from the dead,
it's because parasites have figured out how to control the behavior of their animal hosts.
For example, a parasitic fly lays eggs in a honey bee's body.
The beset bee leaves the hive one night,
then crawls in zombie-like circles before dying.
The fly larvae hatch from the bee's body to seek their own victims.
Then there's the parasitic hair worm that lives inside crickets.
Crickets can't swim but the worm forces the cricket to jump into water
when it's ready to emerge and start its next phase of life.
And then there's the fungus that can infect tropical tree-dwelling ants.
When the ants are infected by the fungus, they crawl out to a spot on the tree where the fungus can thrive.
Then the fungus kills the ant and eats its body from the inside out,
sprouting spores from the ant's head.
Other ants pick up these spores; now they're doomed as well.
So how do these dastardly parasites do it?
Scientists think these parasites can control or mimic molecules in the animals' brains that influence behavior.
And no, humans are not immune to getting "zombified" by parasites.
Researchers think the protozoan, Toxoplasma gondii, might actually change people's personalities
making them more sociable but also reckless.
It's thought that the parasite alters hormone levels and boosts dopamine, making us feel good.
More than 22 percent of Americans might be infected with Toxoplasma gondii
which we catch from house cats.
For Scientific American's zombie edition of Instant Egghead, I'm Katherine Harmon.