How Parasites Commandeer and Change Our Neurocircuits | Kathleen McAuliffe | Big Think

How Parasites Commandeer and Change Our Neurocircuits

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Parasites are more than dormant feeders. Microscopic science is uncovering the ways viruses and bacteria prey on their hosts, influencing them to behave in some very strange ways.Parasites are more than dormant feeders. Microscopic science continues to uncover the very active ways in which viruses and bacteria prey on their hosts, influencing them to behave in some very strange ways. Perhaps the most famous of these is the parasite Toxoplasma gondii, which cats defecate and then rodents pick up from scavenging on the ground. Once inside the rodent, the parasite alters the animal's neurocircuitry such that it becomes sexually attracted to cats. Naturally it's existence proves short-lived from this point forward as the rodent actively courts its main predator. Once in the belly of the cat, the parasite is free to reproduce once more — its bizarre life cycle complete and ready to begin again.

Science journalist and disease researcher Kathleen McAuliffe was shocked to learn that the parasite could — and does — also affect humans. In fact, approximately twenty percent of Americans are believed to be infected with Toxoplasma gondii, which potentially influences their behavior in adverse ways. McAuliffe reports that schizophrenia patients are likely to have two to three times the amount of virus antigens in their body. In addition, international studies have found that suicide rates increase proportionally to the virus's infection rate. Of course any behavior changes caused by the virus are likely to be subtle beyond direct detection, but its effect on human behavior is real.

Another parasite McAuliffe profiles is the parasitic barnacle which can attach itself to a crab and inject a small clump of its cells into the crab. "Those cells then grow into a tangle of root like structures," she says, "and these roots wrap around all the crab's internal organs and eventually even sterilize the crab. Where the crab would normally grow a brood pouch on the bottom of its belly to incubate it's young, the parasitic barnacle pushes out of the crab and grows a brood pouch of its own. And from that moment forward this crab lives and exists solely to feed the parasite and to take care of it's young."

It all goes to show the wonder of the microscopic world, and how our free will is so commonly influenced by factors widely out of our control. Beyond social, cultural, and historical factors, there are biological agents inside of us which affect how our brain functions, and so how we interact with the world around us.

Kathleen McAuliffe's book is This Is Your Brain on Parasites: How Tiny Creatures Manipulate Our Behavior and Shape Society

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KATHLEEN MCAULIFFE

Kathleen McAuliffe’s articles, many featured on covers, have appeared in over a dozen national magazines, including Discover, The New York Times (both the Sunday Magazine and newspaper), US News & World Report, Smithsonian, Atlantic Monthly, More Magazine, Glamour, and Reader's Digest. In addition to being a feature writer, McAuliffe was a health columnist for More Magazine from 1999-2006. A decade earlier, she founded a quarterly newsletter put out by the American Foundation for AIDS Research, which she edited for the first year of its publication. From 1985 to 1988, she was a senior editor at US News & World Report, focusing on the coverage of health and science. In the six years previous to this position, she was an editor at Omni Magazine, where she assigned and prepared science articles for publication. During that period, she also co-authored Life for Sale, one of the first popular books about the genetic engineering revolution

Her article, "Are We Evolving?", was featured in The Best American Science Writing 2010, edited by Jerome Groopman. The year before, she was awarded an Alicia Patterson Journalism Fellowship to study and report on human evolution. In 2000, she received an award from the National Coalition of Women With Heart Disease in recognition of excellence in journalism. Twelve years earlier, she was honored with the Institute of Food Technology award for outstanding writing on food science and nutrition. McAuliffe was also awarded a science writing fellowship in 1996 from the Marine Biological Laboratory at Woods Hole.

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TRANSCRIPT

Kathleen McAuliffe: We know that parasites can make us sick, of course, and siphon off our nutrients, but it's very surprising to hear that some of them, in fact there may be a large number,

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