Monday, January 30, 2012

Fun with selection!

Today I thought of an easy and fun way to understand the process of selection in evolution.   I believe it would be a good way to teach children about evolution and a good response to anyone dragging out that tired old metaphor about the parts of a jumbo jet coming together randomly.

Just to cover my butt, I am sure someone else has come up with this idea before, but a quick google search didn't reveal anything.  If you know someone wrote about this before me, please let me know so I can attribute it to them.

Anyhow, here is what you do:  get five dice.  Rolling all five dice at once, try and get the same number on all five on the same roll.  This is unlikely to happen.  According to Wolfram Alpha, the odds of getting the same number on all five dice on the same roll are 1 in 1296.  Now try getting not just five of the same number, but five of a specific number, say one, on the same roll.  It is not going to happen unless you are very very lucky.  

Now let's change the rules a little.  Now, when you roll all five, any dice that come out a one you can set aside.  Roll the remaining dice and set aside the ones.  Repeat until all the dice show a one.  As I am writing this, I gave it a try and it took 14 rolls to get all of the dice to show one.  This is in keeping with the numbers I got earlier when I did this same thing eighteen times.  The average number of rolls was between twelve and thirteen (five was the lowest and twenty-two the highest).  

So in a fairly small number of rolls through the mechanism of selection, we are able to accomplish something that would otherwise be very improbable.  

Anyhow, I am sure you have heard of similar examples.  I just thought this one was fun because you can actually do it.

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