Re: Predator At The Chessboard Pdf Download
Takeshi Krueger
There are various definitions of "board sight" or "board vision" in chess, but fundamentally it means the ability to (mentally) see all of the various possibilities for moves by your pieces (and those of your opponent). While it is closely related to your level of tactical skill, it is not quite the same thing. In fact, I would say that, once you have been exposed to the full range of tactical ideas and patterns, whether through books like Understanding Chess Tactics or sites like Predator at the Chessboard, more often it is a failure of board sight in a particular position that will trip you up and cause you to miss a tactic. There are examples of this at all levels, including Kramnik's infamous missed mate-in-one.
One of the benefits of analyzing your own games is to see how particular issues repeatedly appear in them, which allows you to better correct them in future games. When looking at missed tactics, it is therefore very important to understand why you missed them - both for yourself or your opponent. In the latter case, I have long had a bias toward focusing on my own plans over the chessboard and not looking hard enough at the possibilities for my opponent; I have been working on this using a better thought process with tactics training. This expansion of mental focus, while helpful in general, will not necessarily eliminate board sight problems - although it should at least increase my chances to spot additional threats.
Your comments and ideas on chess training and this site are welcomed.
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Professor Stephen Stearns: Welcome Orgo survivors, and others. I stuck this slide up, sort of outside the framework of the regular lecture, and I did so just to indicate that if you go through the scientific literature, you can probably find a neat case of coevolution, with some kind of beautiful biology in it, coming out every week. This one came out last week.
This is a Proboscis fly that lives in South Africa, and it pollinates flowers. And you can see that it has evolved a very long proboscis, and the flower has evolved a very long nectary, and it looks, in fact, very much like Darwin's orchid, and that moth called Praedicta, that Darwin predicted would have a long proboscis. But this is a fly. This is not at all closely related to moths, and that flower is not at all closely related to orchids. So this is convergent evolution.
And I think you'll remember, in reading the book, that there was a neat alternative hypothesis posed in the book saying, "Hey, it wasn't about the coevolution of the flower and the moth. There's a spider that sits on the orchid, and when the moth flies in, the spider tries to eat the moth; and so the moth kind of evolved a long proboscis so that it wouldn't touch that flower with anything but a ten-foot pole. Okay? So that was an alternative hypothesis, and there's actually some evidence for that in the case of the orchid on Madagascar.
But in the case of this interaction, which is in Cape Province in South Africa, with a fly and something that is not at all an orchid, the data indicate that, in fact, a coevolutionary story works just fine; and that looks to be what's going on. The longer the nectary, the more likely the pollination; the longer the proboscis, the greater the energetic reward--and the two things feed back and forth to each other.
So this indicates actually that Darwin's original idea was probably correct. And I would note that in the case of the orchid on Madagascar, the fact that there's a spider doesn't really mean that Darwin was wrong in generating his story, it just means that there is also something else going on.
Okay, so. We spent the first part of the course talking about microevolution. We spent the second part of the course talking about macroevolution. And today and Monday, we're going to talk about coevolution and evolutionary medicine as two areas in which micro and macroevolution interact in generating explanations of things.
And I think that you'll probably see, if you think about it, that in almost any reasonably complicated or large-scale biological pattern, both things have been involved; both micro and macroevolution. There's been some things that have been changing slowly and some things that have been changing quickly.
Now the tight genetic definition of coevolution is this. In one species you have a change in a gene, and that--excuse me for missing this; I was doing proofreading this morning; there should be 't' there--it stimulates an evolutionary change in a gene in the other species, and that change in the other species stimulates another change in the first species; so that you have kind of a gene for gene succession in time. One thing happens here; that stimulates something here; that stimulates something here.
That is the tight genetic definition of coevolution. If you could demonstrate that, I think everybody would agree, hey, you nailed it, it's really there. It's hard to do. The reason it's hard to do is that we don't normally know what the genes are that involved. We can see the phenotype, but we have difficulty inferring the genes. There are some cases of this that are well documented in rusts, rust fungi inhabiting wheat; Ustilago hordii is one of them. So, you know, pathogens of crop plants are things where this kind of coevolution is well documented.
Another kind of coevolution is phylogenetic. So you use tree thinking to try to infer what's been going on. And you look at closely interacting organisms--pathogens, parasites, pollinators, things like that--and you see if the trees can be laid right on top of each other.
Or, if you have one group over here--so you have, say, the pathogens over here and you have the hosts over here--you see if the trees line up and touch each other at the tips. That would indicate--without any crosses, so you don't see any lines kind of crossing over when you line them up--that would mean that the trees have exactly the same topology, and that every time the host speciated, the pathogen speciated. And if you see crossing lines, it means that a pathogen has jumped from one host to another. So that kind of approach gives you another definition of coevolution, and another tool for trying to infer it.
Now before I get into coevolution proper, I want to talk a little bit about co-adaptation, because co-adaptation actually contains within it a message that's of general significance for coevolution. Right at the beginning of life, the first replicators had to co-adapt in order to generate say a well-functioning hypercycle; they had to co-adapt to each other. And at the level of the cell, when you're looking at key molecules in the cell, all these interactions have co-adapted to each other.
So, for example, the ribosome here is in green, and you've got the mRNA coming into it like a ribbon, and you've got--the transfer RNA is pulling in the amino acids out at their tips, into the reaction center of the ribosome. And that brings the amino acids into close juxtaposition where an enzyme can operate on them to join them, and then clip them off of the incoming tRNAs, which then go on out, back into the cell to do their job again, and the protein grows out here.
Well, this is a rough sketch of the structure of the ribosome. It's actually more complicated than that, and it has really a beautifully sculpted reaction center in the middle of it. And the message from this is that every single important biochemical step and morphological structure inside the cell is tightly co-adapted, so that form matches function, throughout the cell.
And the reason that's the case is that these things are processing reactions that happen thousands of times a second, and that therefore accumulate to have big effects over the lifetime of the organism. If you've got something in you that is going to happen say 50 billion times in your lifetime, and you get a very, very tiny, 1/1000th of 1% change in it, that then accumulates 50 billion times, you have a massive result at the end of your life. So that things that are happening down at that level are driven by high frequency interactions. And the frequency with which things interact is one of the key elements of coevolution, in general.
If you look at a slightly higher level in the cell, you can find co-adaptation going on again. The axons that run into nerve fibers have different lengths, so that the signal coming from the brain will arrive at things that need to be coordinated at the same time. The muscles in electric eels have been turned into storage batteries, and the axons that run from the brain have had their lengths modified, so that they hit the different cells in the storage battery at exactly the same instance, so that the electrical charge goes out, all at the same time.
A four- or five-foot electric eel can kill a horse; that's how much electricity they can store up. But they can only do it because it's released exactly at the same time. If it dribbled out, it wouldn't take the horse down; or the naturalist exploring the shallow river in South America. Right?
Same kind of thing in your brain. There's very tight co-adaptation between your retina and its projections into the visual cortex at the back of your brain. So these connections have been sculpted by evolution so that the re-creation of the external world, in your head, is precise. And this has gone on in every organ of your body in one way or another. So the integration of the organism is achieved by co-adaptation of its parts.
That's not precisely the gene for gene kind of interaction between species, that people think about in coevolution, but it is a gene for gene interaction in the determination of those organ systems. A gene changes over here, and another gene has to change over there. It's just that the process is going on inside a single genome, rather than in two different genomes.
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