Mind-controlling parasites date back millions of years

http://www.msnbc.msn.com/id/38747237/ns/technology_and_science-science/

By Charles Q. Choi
updated 8/17/2010 8:15:18 PM ET

Mind control by parasite sounds like the stuff of science fiction, but not only have scientists revealed that it is real across a range of animals including perhaps humans they now even have fossil evidence suggesting it has taken place for millions of years.

An unnerving variety of parasites have evolved the ability to control the brains of victims to help the parasites spread. For instance, the protozoan known as Toxoplasma gondi imakes rats love cat urine so that it can spread among its feline hosts and it may influence human culture as well, making people more prone to certain forms of neuroticism.

Another case of parasite mind control involves the fungus Ophiocordyceps unilateralis, which essentially turns ants into zombies. It maneuvers the insects into biting down on the major veins of the undersides of leaves just before they die the fungus then rapidly grows a stalk from their victims' heads, releasing spores to infect more ants.

Now scientists have discovered what might be ancient evidence of such mind-control-induced death grips scars on a roughly 48-million-year-old leaf.

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"We are now realizing that half of life on Earth is parasitic — each free-living organism has at least one parasite," Hughes said. "But very few manipulate behaviors and there is a reason for that — it is likely very costly.

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