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Kingswood · 02-20-2007, 11:05 PM

Here is a simple demonstration that shows how evolution works. I will describe a model that has physical objects, but running a computer simulation according to these rules may be more efficient.

You will need objects of two different contrasting colours, and a way to bind them together in pairs. Transparent plastic containers that hold kids' toys and red and yellow marbles would do the trick. You will need 80 containers and 160 marbles of each colour.

Experiment 1

Have 20 containers, 19 of them with two yellow marbles and one with one yellow and one red. Randomly pair these containers off into 10 pairs of two. For each pair of marbles, combine them like gametes in all four different ways. The red-yellow container should have two children that are also red-yellow.

Now we simulate predation. Place all the items into a bag and randomly pull them from the container. For each red marble a container has plus one, flip a coin. If the coin comes down heads, place the container back into the bag. Repeat the above until 40 containers remain in the bag.

We then simulate random chance. Pull 20 containers from the bag and set them aside without flipping coins. The 20 that remain form the breeders for the next generation.

If the above is repeated many times with the progeny of one generation forming the base for the next (this is why a computer simulation is good), the chances are good that the red "mutation" may become established, and eventually most of the containers will contain at least one red marble.

One may also find that the mutation does not become established. This demonstrates that beneficial mutations are no guarantee of fitness on their own becuase other factors in their environment also impose pressures for which the mutation offers no benefit.

Experiment 2 - control

Repeat experiment 1, but make the "red" mutation have no effect on survival. This time, one will find the results to be different. The mutation will tend to die out, and if it does become established it is unlikely to spread through the population.

02-20-2007, 11:05 PM	#9
Kingswood Draco dormiens nunquam titillandus Join Date: Nov 2005 Location: Melbourne, Vic Posts: 316	Here is a simple demonstration that shows how evolution works. I will describe a model that has physical objects, but running a computer simulation according to these rules may be more efficient. You will need objects of two different contrasting colours, and a way to bind them together in pairs. Transparent plastic containers that hold kids' toys and red and yellow marbles would do the trick. You will need 80 containers and 160 marbles of each colour. Experiment 1 Have 20 containers, 19 of them with two yellow marbles and one with one yellow and one red. Randomly pair these containers off into 10 pairs of two. For each pair of marbles, combine them like gametes in all four different ways. The red-yellow container should have two children that are also red-yellow. Now we simulate predation. Place all the items into a bag and randomly pull them from the container. For each red marble a container has plus one, flip a coin. If the coin comes down heads, place the container back into the bag. Repeat the above until 40 containers remain in the bag. We then simulate random chance. Pull 20 containers from the bag and set them aside without flipping coins. The 20 that remain form the breeders for the next generation. If the above is repeated many times with the progeny of one generation forming the base for the next (this is why a computer simulation is good), the chances are good that the red "mutation" may become established, and eventually most of the containers will contain at least one red marble. One may also find that the mutation does not become established. This demonstrates that beneficial mutations are no guarantee of fitness on their own becuase other factors in their environment also impose pressures for which the mutation offers no benefit. Experiment 2 - control Repeat experiment 1, but make the "red" mutation have no effect on survival. This time, one will find the results to be different. The mutation will tend to die out, and if it does become established it is unlikely to spread through the population.