Zombie Science

Katharine Harmon at Scientific American is fascinated by zombies ... in particular, animals whose parasites turn them into zombies. Here are three pieces from her ongoing series. (Sorry I'm late for Halloween with this post. Ah, well, zombies are always timely.)

Start by watching her 2-minute video on Scientific American's "Instant Egghead":

How Do Animals Become Zombies? Instant Egghead [Video]

Scientific American explains how animals--and possibly humans--can become real-life zombies

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ZOMBIE WORLD: Parasites are responsible for many of the real-life zombies in the wild kingdom.Image: Instant Egghead

It may sound like something straight out of a horror movie, but many animals can come under the zombie-like control of parasites. So what about humans? Scientific American editor Katherine Harmon fills us in on the ghoulish side of Nature ...

[Note: The cat isn't our zombie here, in spite of the eyes. But house cats are the source a parasite, Toxoplasma gondii, which may infect 20% or so of us humans. T. gondii can change our hormone and dopamine levels, making us "more sociable, but also reckless".]

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Then take a look at her overview article and slide show of zombie critters:

Zombie Creatures: What Happens When Animals Are Possessed by a Parasitic Puppet Master? [Slide Show]

From fungi to flies, some parasitic species have figured out how to control their host's behavior to get what they need. See what happens when bugs go really bad

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ON THE DARK SIDE?: Some tiny organisms can make much larger animals do their dirty work for them. Find out how parasites can take control of bodies and minds.Image: STEVE YANOVIAK

A spider, seemingly possessed, spins an uncharacterisitic web—just before wasp larvae nesting on its abdomen suck the last nourishing juices from the spider's dying body and make a cocoon in the weird web.

A worm gets into the brain of a shy, shade-loving snail, compelling it to crawl out of its safe home and into the open where it gets attacked by a bird—which is destined to be the parasite's next host.

Creepy tales like these are happening all over the animal kingdom, and not just on Halloween or under a full moon. Some organisms have taken evolutionary advantage to a whole new level, achieving success by insidiously—and still quite mysteriously—changing the behavior of another animal against its will ...

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And, finally, take a look at her most recent article on how being a zombie-ant fungus isn't without its dangers ... in the form of parasitic fungi of its own:
Undead-End: Fungus That Controls Zombie-Ants Has Own Fungal Stalker

A specialized parasite fungus can control ants' behavior. But that fungus also faces its own deadly, specialized parasites

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ZOMBIE-ANT FUNGUS FEAST: New research is uncovering how zombie-ant fungus might control its hosts. But this parasite also has its own fungal threats.Image: Wikimedia Commons/David Hughes/
Maj-Britt Pontoppidan/PLoS ONE

An unsuspecting worker ant in Brazil's rainforest leaves its nest one morning. But instead of following the well-worn treetop paths of its nest mates, this ant stumbles along clumsily, walking in aimless circles, convulsing from time to time.

At high noon, as if programmed, the ant plunges its mandibles into the juicy main vein of a leaf and soon dies. Within days the stem of a fungus sprouts from the dead ant's head. After growing a stalk, the fungus casts spores to the ground below, where they can be picked up by other passing ants.

This strange cycle of undead life and death has been well documented and has earned the culprit the moniker: "zombie-ant" fungus—even in the scientific literature. But scientists are just learning the intricacies of this interplay between the Ophiocordyceps parasitic fungus and the Camponotini carpenter ants that it infects. Fossil evidence implies that this zombifying infection might have been happening for at least 48 million years. Recent research also suggests that different species of the fungus might specialize to infect different groups of ants across the globe. And close examination of the infected ant corpses has revealed an even newer level of spooky savagery—other fungi often parasitize the zombie-ant fungus parasite itself ...