Mind-Control Microbe
A bug in your body can give you schizophrenia, make you have a car crash, or determine the sex of your child.
Five years ago, Oxford University zoologists showed that the parasite Toxoplasma gondii alters the brain chemistry of rats so that they are more likely to seek out cats. Infection thus makes a rat more likely to be killed and the parasite more likely to end up in a cat—the only host in which it can complete the reproductive step of its life cycle. The parasite also lives in the brain cells of thousands of species, including about 60 million supposedly symptom-free Americans. Studies over the past few years have suggested that toxoplasmosis infections in humans, too, may cause behavioral changes—from subtle shifts to outright schizophrenia. Two studies this year add even weirder twists.
U.S. Geological Survey biologist Kevin Lafferty has linked high rates of toxoplasmosis infection in 39 countries with elevated incidences of neuroticism, suggesting the mind-altering organism may be affecting the cultures of nations.
Stranger still, parasitologist Jaroslav Flegr of Charles University in Prague thinks T. gondii could also be skewing our sex ratios. When he looked at the clinical records of more than 1,800 babies born from 1996 to 2004, he noted a distinct trend: The normal sex ratio is 104 boys born for every 100 girls, but in women with high levels of antibodies against the parasite, the ratio was 260 boys for every 100 girls. Exactly how the parasite might be tipping the odds in favor of males isn't understood, but Flegr points out that it is known to suppress the immune system of its hosts, and because the maternal immune system sometimes attacks male fetuses in very early pregnancy, the parasite's ability to inhibit the immune response might protect future boys as well as itself.
"Our present study was rejected by eight journals, usually without any formal review," says Flegr, who had the same problem publishing an earlier one showing that infection more than doubles the odds of a person having a traffic accident. "People don't like the possibility that their behavior and life are manipulated by a parasite," he says.
If altering our culture and causing car crashes weren't bad enough, toxoplasma may actually wheedle their genes into our genomes.
There are plenty of other theories about what affects the reproductive sex ratio. Some of them are actually true.
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Brain reader triggers call for Neuroethics
Tom Heneghan
Reuters
Thursday, 15 February 2007
News of a brain scanner that can read a person's intentions has led to calls that neuroscientists should debate the ethics of their work before it can be misused by governments, lawyers or advertisers.
The fledgling field of "neuroethics" has emerged in the wake of rapid progress in research aimed at unlocking the brain's secrets.
Some neuroethicists say the same discoveries that could help the paralysed use brain signals to steer a wheelchair or write on a computer might also be used to detect possible criminal intent, religious beliefs or other hidden thoughts.
"The potential for misuse of this technology is profound," said Dr Judy Illes, director of the Stanford University's neuroethics program in California. "This is a truly urgent situation."
A research paper published last week showed neuroscientists can now not only locate the brain area where a certain thought occurs but probe into that area to read out some kinds of thought occurring there.
Its author, Dr John-Dylan Haynes of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, compared this to learning how to read books after simply being able to find them before. "That is a huge step," he says.
Haynes hastened to add that neuroscience is still far from developing a scanner that could easily read random thoughts.
"This could be really big
Haynes and his research team used functional magnetic resonance imaging to detect a volunteer's unspoken decision to add or subtract two numbers flashed on a screen. They got it right 70% of the time.
Farah, Illes and Sahakian are among a small group of neuroscientists who founded the Neuroethics Society in May 2006 to promote an international debate about the proper use of the discoveries their field was making and will make in future.
"But we need to think about those ethical implications right now.
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