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View Full Version : Dice Game to Explain Natural Selection and Evolution

Arlanthe
2007-02-06, 07:08 AM
I developed an interesting illustration of natural selection, using dice, first used to explain the concept to a fence-sitting creationist.

Like many gamers, I have a sack of dice so large it could be used to bludgeon someone to death. I selected twenty of each type of die, all the same size, and put them in a plastic bucket that was formerly used to hold loose change. I asked the creationist “so what are the chances that I roll a one on all of these dice?” “Extremely small” she admitted. Her entire problem with evolution and natural selection was that it was “too random” and “improbable” that an organism adapt in a constructive way. That’s a fair point for a person who really doesn’t understand the concept.

I responded by saying asking, ”if we do something seemingly improbable now with these dice, maybe you’ll see that it is indeed possible”. She nodded skeptically. I cast all of the dice out on the table, and they tumbled out into a random pile of numbers. “Well, it looks like we didn’t do anything improbable that time”. There was nothing interesting or improbable about the numbers that were rolled. My mark smirked triumphantly. I told her to go ahead and have a go at rolling, and maybe something deceptively improbable will happen after all. So we continued chatting about the issue as she scooped up the dice and dumped them a fistful at a time into the bucket.

“Stop”, I said, when she was most of the way finished with putting the dice back into the bucket. We looked at the remaining dice on the table. There were 16 four sided dice, a couple of 6 siders, and maybe an eight sider or two. All of the 10, 12, and 20 sided dice were in the bucket. Over three quarters of the four sided dice were still on the table, comprising four-fifths of the remaining dice. Without even looking at what she was doing, blindly and randomly picking up dice and dumping them into the bucket, she had inadvertently illustrated natural selection to herself. It was the shape of the dice that was important (as with animals), not the numbers on the dice- those were just used as a foil. It was very statistically improbable that the remaining dice count would come out the way it did with all of the 10-sided and above dice ending up in the bucket, and most of the four siders “surviving”. Yet I was confident enough in what would happen to run this practical experiment. At that moment, realization dawned on her.

The four sided die is more “fit” to survive in an environment where fists are grabbing at dice. I went on to explain that there were minor (and sometimes major) mutations in all organisms, caused by chemical transcription error and radiation (among other things). This variation within a species provides the change necessary for evolution. Some of the “dice” species were pointier, and some were more bulbous. In a world where hand predators eat dice for food, the fewer sides you have, the more likely you will survive to pass on your genes. It is the same with all animals, I explained. Imagine that the dice are gazelles, and the hand is a tiger. In that analogy, the four sided dice would be the faster gazelles- less likely to get eaten by the tiger, which will most often catch the slower (easier to grip) dice/gazelles. So after many generations, the dice pool begins to look more liked a four sided die population (the gazelles evolve to become faster, longer legs, more efficient muscles, and so forth). The faster ones don’t get caught and breed other fast gazelles! The same selection pressure favored creatures with long necks who could breed more because they got leaves higher in the trees (giraffes), stealthier predators who hid better (tigers), and plants with stickier seeds that could spread them farther (burrs).

If you are slightly better than all of the other organisms of your type, it is easier for you to survive to pass your genes on and win! Then the future generations look more like you! After millions of years, a lot of generations can cause a lot of changes, and lead to some pretty interesting survival traits.

I am currently planning on taking this idea a step further by collecting six sided dice of the same size and weight, but varying roughness, and seeing how well the slicker members of the D6 species survive the hand-predator than rougher members of the species. I’d like to make an educational game out of some concepts like this to explain natural selection and evolution to school children, and people with a school-aged understanding of evolution.

Premier
2007-02-06, 07:26 AM
Interesting story, thanks for sharing.

I'm curious, how much did you manage to convince her in the end?

Arlanthe
2007-02-06, 08:05 AM
Interesting story, thanks for sharing.

I'm curious, how much did you manage to convince her in the end?

This was actually several years ago.

Well, she was a university student with me in san Diego at the time (in the U.S., where the creationists live). By the end of her four years there I believe she has adopted the "evolution definitely occurs, but God set the universe up so it would happen that way" school of thought. Which is fine, she accepted the point.

Indon
2007-02-06, 12:48 PM
I am intrigued by this, but I was expecting something more algorithmic. I mean, you could do that kind of scenario with a couple people eating jelly beans (so long as there's a licorish flavor, you know).

Arlanthe
2007-02-07, 02:07 AM
I am intrigued by this, but I was expecting something more algorithmic. I mean, you could do that kind of scenario with a couple people eating jelly beans (so long as there's a licorish flavor, you know).

That's a good one too. Black jelly beans are like the poisonous frogs or distasteful butterflys that are eaten less because animals don't like the way they taste. They survive to pass on their genes!

Great example- I'd never thought of that, kudos to you.

Zangor
2007-02-07, 02:59 AM
That's a pretty cool idea!
I heard about one demonstration, where a teacher cut out a bunch of strips of paper. All different colors. Green, blue, red, and about 10 other colors or so. He then spread them around outside in the grass, and, when his students came in, told them that they were looking for these insects, and he held up a few of the strips of paper. He then had them look for half the class period, and called them in. The ones that were furthest from green, (Red, pink, white, etc.) were almost all found, but most of the green ones never were found. He then explained that they'd pass on their genes, more and more until green was almost all that was left.

InaVegt
2007-02-07, 12:30 PM
This is a nice idea, only flawed in that dice aren't anything like living creatures and as such any parallel between them is inherently flawed.

Gezina van den Vechte, Fallen celestial, Champion of Hell, there when the world was created

Arlanthe
2007-02-07, 01:18 PM
This is a nice idea, only flawed in that dice aren't anything like living creatures and as such any parallel between them is inherently flawed.

That's like saying using an onion to explain geologic strata is flawed because it is a vegetable and not a rock, or using balls and sticks to explain atomic bonds is flawed because the sticks don't actually have quantum numbers.

The dice game is an analogy, like many educational tools. If a person comes away understanding a concept better after seeing an intuitive demonstration, then you cannot call said analogy "inherently flawed". Quite the opposite: it has served its purpose.

Once students understand the concept of natural selection, then they can go on to study real observations of natural selection and genetic drift such as the heike crab, drosophila melanogaster studies, recent Australian swallow beak mutations, and that kind of thing.

A little analogy goes a long way.

Zangor
2007-02-14, 03:47 AM
Hey! I was just having some trouble explaining why micro/macro evolution are the same thing, that if one exists then the other must, and I, remembering this thread, was able to use a gaming example, so I thought I'd share it.

Okay, the guy I was explaining it to is a pretty big Armored Core fan. If you've never played any of the series, you build and go on missions in a giant robot. Kinda like MechWarrior, but you build your machine from different parts.

So, I said to him. You start with your basic AC, right? Then, when you have a bit of money, you buy a new part. Say, a replacement head. Now, after this, you still have, basically, the same AC. It's a little better, but it's mostly the same. This is micro evolution.

Now, as you complete missions and get more money, you slowly aquire more and more parts. One by one, your machine changes, until it doesn't have a single part in common with your original AC. At each stage of building this AC, though, you only usually changed one or two parts, because it was all you could afford. They added up to make this complete difference. That's "macroevolution," as you call it.

He actually thought about this a bit and now seems to be leaning towards accepting science. :smallbiggrin:

Lord Zentei
2007-02-14, 06:55 AM
Another approach might be to see how long it takes to get a load of ones with a bucket of dice if you both retain and re-roll.

Often, creationists will claim that the probability of an ideally adapted organism is too small since the numbers of permutations of alleles is so high. In the dice analogy, for instance, with twenty d6s, the chances of getting twenty ones would be 1:6^20, which is vanishingly small. So: how often would you have to roll the bunch of dice to get such an outcome once, on average? Presumably something like 6^20 times... or over 3656 trillion times!

That is to say, it would be so, unless you retain all the ones after each roll, in which case the number of re-rolls becomes very small indeed - at least very small compared with 6^20. The genetic material of each generation is inherited from the most successful members of the previous generation, after all, its not selected from scratch. Evolution is about gradual improvement, and with "memory" of the previous design.

Incidentally, here is a useful site:

http://www.rennard.org/

Check out the java applet that simulates evolution: linka (http://www.rennard.org/alife/english/gavintrgb.html).

Arlanthe
2007-02-16, 08:01 AM
Great point Zentai! But creationists don't seem to understand statistics so well. That's worth a try though- 20 D 6s and re-roll ones. Maybe a dozen tries at most to get the last one?

Lord Zentei
2007-02-16, 08:08 AM
Great point Zentai! But creationists don't seem to understand statistics so well. That's worth a try though- 20 D 6s and re-roll ones. Maybe a dozen tries at most to get the last one?

It varies how many you need, of course, that is one of the troubles of using a stochastic model. :smallwink:

Hazarding a guess: somewhere between a dozen and a couple of dozen rolls might be needed. Maybe more if you are unlucky.

Though creationists are not always good at statistics, they are fond of calculating the number of tries needed for this sort of thing, so I guess that should do the trick.

EDIT: here's a more qualitative method for understanding why this should be the case. Ask them: if it takes a child five minutes to eat an apple, how long would it take twenty kids to eat one apple each? 100 minutes is the wrong answer, of course, since the kids eat the apples simultaneously.

So, here is an improvement of the above: try ten dice. Let's say that it takes about 15 tries to get all ones. Then try ten dice again. Let's say that this would take 18 tries.

Ask, how long it would take with 20 dice... If the person says "33 tries" remind them of the children and apples question, and handle the rolls like this: "OK, we'll do it with 20 dice. To divide our labour, I'll roll these ten dice, and you'll roll those ten dice, and we'll make our rolls simultaneously, as would be inevitable if one person were doing all the rolling by himself". If they don't change their minds at that point, go for it. ;)

Larger numbers of dice thus only take longer than smaller ones, because the number of re-rolls needed for a any given number of dice is not fixed: if you were to repeat the 10-dice experiment a large number of times, there would be a whole bunch that took only a dozen or so attempts and a small number that took a lot longer... with multiple batches of 10 dice, the whole takes as long as the batch of 10 that took the longest, like the slowest member of the caravan -- or the slowest eater among the children.