Finding parasitic behavior
Two adjacent stories, both by Tina Hesman Saey, at first glance may appear to be unrelated but in actuality show examples of a well-known phenomenon: parasites adversely affecting the behavior of the host so that the parasite can get to its next victim.

The article “Belly bacteria can boss the brain” (SN: 10/8/11, p. 9) is an example of such behavior. A stressed-out wild mouse that clings to walls and avoids swimming is a mouse that lives to breed another day. Being relaxed is no more beneficial to it than climbing to the top of the tree is for the caterpillars in “Virus gene turns gypsy moth caterpillars into climbers” (SN: 10/8/11, p. 9).

Can human apathy — or any behavioral extreme — be a symptom of a parasitic infection (bacterial, viral or other)? Perhaps instead of finding a solution to problems, researcher John Bienenstock found an explanation.
Fran Tabor, Kalispell, Mont.

An editorial gem
I am sure I speak for others when I say the thing I most look forward to in each Science News issue is Tom Siegfried’s perspective. Always a first read, I’d never have guessed an editor could play as big a role in what I choose to read. He is a real down-to-earth multifaceted gem who makes your publication great.
Mark Carr, Brinnon, Wash.

Water makes geology slippery
The article “Weather affects geologic activity” (SN: 12/31/11, p. 8) seems to ignore the possibility that the increase in geologic activity may be due to something besides the lightening and drying of the upper crust with the reduction of the winter snow-and-ice pack.

That mechanism certainly makes excellent sense; however, another paradigm leaps to my mind: While the weight of the ice is being reduced — and before drying can commence to any great extent — the ground below the ice is being saturated with water.

Water, as schoolchildren who pay attention know, is the “universal solvent”; a tiny bit of thought also reveals water to be the “universal lubricant.” As the ice pack is being lightened, it is simultaneously lubricating the ground below — as deeply as the fissures allow, which may be very, very deep.
Scott McCleve, Douglas, Ariz.

Water can indeed act as a geological lubricant. In fact, this was the first idea that researcher Thomas Ader and his colleagues considered when they noticed a link between monsoons and earthquakes in the Himalayas. But computer simulations of water lubricating the fault simply could not reproduce the back-and-forth motions recorded by the GPS stations. — Devin Powell

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