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Zombies April 13, 2011

Posted by Ezra Resnick in Evolution.
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The jungle can be a dangerous place.

Four new species of brain-manipulating fungi that turn ants into “zombies” have been discovered in the Brazilian rain forest.

These fungi control ant behavior with mind-altering chemicals, then kill them…

Once infected by spores, the worker ants, normally dedicated to serving the colony, leave the nest, find a small shrub and start climbing. The fungi directs all ants to the same kind of leaf: about 25 centimeters above the ground and at a precise angle to the sun (though the favored angle varies between fungi)…

Before dying, ants anchor themselves to the leaf, clamping their jaws on the edge or a vein on the underside. The fungi then takes over, turning the ant’s body into a spore-producing factory. It lives off the ant carcass, using it as a platform to launch spores, for up to a year.

Watch this video if you dare:

Such parasitic phenomena are not at all rare in nature. One interesting thing to notice is that the behavior of an infected host appears utterly baffling, until we understand that it is serving the parasite’s interests and not its own. Daniel Dennett opens his book Breaking the Spell: Religion as a Natural Phenomenon using zombie ants as an analogy:

You watch an ant in a meadow, laboriously climbing up a blade of grass, higher and higher until it falls, then climbs again, and again, like Sisyphus rolling his rock, always striving to reach the top. Why is the ant doing this? What benefit is it seeking for itself in this strenuous and unlikely activity? Wrong question, as it turns out. No biological benefit accrues to the ant. It is not trying to get a better view of the territory or seeking food or showing off to a potential mate, for instance. Its brain has been commandeered by a tiny parasite, a lancet fluke (Dicrocelium dendriticum), that needs to get itself into the stomach of a sheep or a cow in order to complete its reproductive cycle. This little brain worm is driving the ant into position to benefit its progeny, not the ant’s. This is not an isolated phenomenon. Similarly manipulative parasites infect fish, and mice, among other species. These hitchhikers cause their hosts to behave in unlikely—even suicidal—ways, all for the benefit of the guest, not the host.

Does anything like this ever happen with human beings? Yes indeed. We often find human beings setting aside their personal interests, their health, their chances to have children, and devoting their entire lives to furthering the interests of an idea that has lodged in their brains.

Finding the right questions March 10, 2011

Posted by Ezra Resnick in Philosophy.

How does philosophy help us in our efforts to better understand the physical world (if indeed it does)? In an interview with Robert Kuhn at Closer To Truth, Daniel Dennett suggests that philosophers deal with questions rather than answers: “Philosophy is what you have to do until you know what the right questions are.” Once you’re clear that you have a good question, then you go off and try to answer it — and that’s not philosophy, it’s physics, or psychology, or history, etc. Back in Aristotle’s day, everything was philosophy: the boundaries between various domains of knowledge had yet to be drawn. As different questions eventually became clear and distinct, new fields branched off and came to stand on their own.

Philosophy can help you see why certain questions, which are very tempting, are going to mislead you more than help you. Dennett points out that the history of philosophy is in many regards a history of mistakes — “very tempting mistakes, mistakes that very smart people are apt to be tempted by.” Only by studying and understanding those mistakes can we avoid repeating them. Philosophy helps to clarify issues, to raise questions, to articulate underlying reasons. Philosophy can help you see the forest for the trees.

Of course, philosophers can sometimes get carried away…

Competence without comprehension March 4, 2011

Posted by Ezra Resnick in Computer science, Evolution.
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Gaudi vs. termites

On the left, we have Gaudi’s cathedral in Barcelona; on the right, a termite mound. Both structures serve a purpose (or several purposes); and both exist, with their particular characteristics, for a reason. They are not the result of materials being thrown together randomly; it makes sense for us to ask why their features were built one way and not another. And yet, there is a crucial difference between the two.

In a recent lecture at UCLA, Daniel Dennett describes the difference this way: There is a reason why termites build mounds — but it’s not true that termites have a reason for building mounds. Human beings have reasons for the things they do, and they can represent those reasons explicitly. But no termite needs to understand the reasons behind its actions — no one needs to understand them. Complex reasons can emerge from the mindless, purposeless, automatic process of natural selection.

This idea, of course, is extremely counter-intuitive. Dennett quotes one early attack on Darwin, published anonymously in 1868:

In the theory with which we have to deal, Absolute Ignorance is the artificer; so that we may enunciate as the fundamental principle of the whole system, that, in order to make a perfect and beautiful machine, it is not requisite to know how to make it. This proposition will be found, on careful examination, to express, in condensed form, the essential purport of the Theory, and to express in a few words all Mr. Darwin’s meaning; who, by a strange inversion of reasoning, seems to think Absolute Ignorance fully qualified to take the place of Absolute Wisdom in all the achievements of creative skill.

Exactly! This “strange inversion of reasoning” was Darwin’s great insight: a new way of thinking, with profound consequences and explanatory power.

Dennett attributes a comparable “inversion of reasoning” to Alan Turing. Before modern computers, “computers” were humans who performed mathematical calculations manually. To do this, they had to understand arithmetic. But Turing realized that it’s not necessary for a computing machine to know what arithmetic is. And so we now have CPUs, spreadsheets, search engines, all performing complex tasks without understanding what they are doing: competence without comprehension.

This is the opposite of our own personal experience: our competences flow from our comprehension. But evolution shows us that comprehension can emerge as the result, not the cause, of competence. Just as life is ultimately constructed out of non-living parts, understanding can be constructed out of non-understanding parts. The individual neurons in our brain don’t understand anything — but we do.

There must be a continuum, therefore, ranging from a complete lack of understanding to the kind of understanding humans have. Do apes have reasons? Apes fall somewhere in the middle between termites and Gaudi. They have proto-reasons. The same might be said of our more complex computing machines. One day, we will reach the point when computers have full-fledged reasons of their own.

For billions of years on this planet, there was competence but no comprehension. There were reasons, but no one understood them. We have now evolved the ability to look back and see the reasons everywhere in the tree of life — reasons discovered by the same mindless process that produced us.


Useful fictions September 26, 2010

Posted by Ezra Resnick in Philosophy.
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Do negative numbers really exist? To someone unfamiliar with the concept, the idea of a number smaller than zero surely seems meaningless at first. I may have three apples, or five apples, but I cannot have less apples than none. Consider the problem: If Alice has five apples, how many apples must Bob give her so that she will have three apples? It’s not difficult to recall the mindset wherein such a question seems absurd. And yet, thousands of years ago people realized that for many purposes it can be very useful to extend the number line below zero — when keeping track of credit and debt, for instance. After a little practice, we get comfortable with negative numbers and they come to feel just as real as positive numbers. The same is true for imaginary numbers (originally a derogatory term): at first, the idea of a value which yields a negative result when multiplied by itself seems absurd and meaningless, but this concept turns out to be invaluable for representing certain complex physical phenomena, like electromagnetism and quantum mechanics.

Concepts like negative and imaginary numbers are part of an enormous set of mind tools that humans have devised over the ages to help us model the world around us, and these tools underlie many of the amazing achievements of our species. We must be wary, however, of extending unwarranted physical or metaphysical status to our abstractions. Here is one of Daniel Dennett’s thought experiments from his book Consciousness Explained:

Imagine that we visited another planet and found that the scientists there had a rather charming theory: Every physical thing has a soul inside it, and every soul loves every other soul. This being so, things tend to move toward each other, impelled by the love of their internal souls for each other. We can suppose, moreover, that these scientists had worked out quite accurate systems of soul-placement, so that, having determined the precise location in physical space of an item’s soul, they could answer questions about its stability (“It will fall over because its soul is so high”), about vibration (“If you put a counterbalancing object on the side of that drive wheel, with a rather large soul, it will smooth out the wobble”), and about many much more technical topics.

What we could tell them, of course, is that they have hit upon the concept of a center of gravity (or more accurately, a center of mass), and are just treating it a bit too ceremoniously. We tell them that they can go right on talking and thinking the way they were — all they have to give up is a bit of unnecessary metaphysical baggage. There is a simpler, more austere (and much more satisfying) interpretation of the very facts they use their soul-physics to understand. They ask us: Are there souls? Well, sure, we reply — only they’re abstracta, mathematical abstractions rather than nuggets of mysterious stuff. They’re exquisitely useful fictions. It is as if every object attracted every other object by concentrating all its gravitational oomph in a single point — and it’s vastly easier to calculate the behavior of systems using this principled fiction than it would be to descend to the grubby details . . .

The “useful fiction” Dennett is trying to expose here is the concept of a self — a central authority who lives in our heads and is the experiencer of our experiences and the thinker of our thoughts. There is no supreme command center in the brain where consciousness “all comes together,” but the intuition is so strong that many people believe our minds cannot be entirely a product of our brains — there must be something magical, something mysterious, something immaterial going on. But that is to mistake fiction for fact. The idea of a self is indeed a useful fiction, but we must not allow our intuitions and familiar abstractions to constrain our thinking when we set out to investigate how the world really is.