By ROBERT SAPOLSKY - EDGEVIDEO
Added: Fri, 04 Dec 2009 00:00:00 UTC

Thanks to Lemniscate for the link.
http://www.edge.org/documents/archive/edge307.html
The text below is a transcript of the video from the Edge page linked to above and below

[ROBERT SAPOLSKY:] In the endless sort of struggle that neurobiologists have — in terms of free will, determinism — my feeling has always been that there's not a whole lot of free will out there, and if there is, it's in the least interesting places and getting more sparse all the time. But there's a whole new realm of neuroscience which I've been thinking about, which I'm starting to do research on, that throws in another element of things going on below the surface affecting our behavior. And it's got to do with this utterly bizarre world of parasites manipulating our behavior. It turns out that this is not all that surprising. There are all sorts of parasites out there that get into some organism, and what they need to do is parasitize the organism and increase the likelihood that they, the parasite, will be fruitful and multiply, and in some cases they can manipulate the behavior of the host.

Some of these are pretty astounding. There's this barnacle that rides on the back of some crab and is able to inject estrogenic hormones into the crab if the crab is male, and at that point, the male's behavior becomes feminized. The male crab digs a hole in the sand for his eggs, except he has no eggs, but the barnacle sure does, and has just gotten this guy to build a nest for him. There are other ones where wasps parasitize caterpillars and get them to defend the wasp's nests for them. These are extraordinary examples.

The parasite my lab is beginning to focus on is one in the world of mammals, where parasites are changing mammalian behavior. It's got to do with this parasite, this protozoan called Toxoplasma. If you're ever pregnant, if you're ever around anyone who's pregnant, you know you immediately get skittish about cat feces, cat bedding, cat everything, because it could carry Toxo. And you do not want to get Toxoplasma into a fetal nervous system. It's a disaster.

The normal life cycle for Toxo is one of these amazing bits of natural history. Toxo can only reproduce sexually in the gut of a cat. It comes out in the cat feces, feces get eaten by rodents. And Toxo's evolutionary challenge at that point is to figure out how to get rodents inside cats' stomachs. Now it could have done this in really unsubtle ways, such as cripple the rodent or some such thing. Toxo instead has developed this amazing capacity to alter innate behavior in rodents.
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Continue reading and to video
http://www.edge.org/documents/archive/edge307.html

TAGGED: BIOLOGY, EVOLUTION, SPEECHES