Tuesday, July 11, 2006

Darwinian Study: Replicators (part 2)

(Part 2)

Also, remember that a replicator only has to develop once during this time. Once it forms, it will begin replicating. The first replicator will become two. Each of those two will become two. Each of those four will become two. Each of those eight will become two. Each of those sixteen will become two. And so on.

This exponential growth rate will result in a lot of resultant replicators over a short period of time. If it takes 1 month for a single replicator to replicate (which is a long replication time for a single molecule), after 1 year, 4,096 replicators will be floating around. After 2 years, there will be over 16 million replicators! And we've had several hundred million years for all this to occur.

The evolution of these replicators into what we see today in our genes is a topic for another study.

Successful replicators exhibit three properties:

1. Copying Fidelity

If a replicator copied itself and regularly made errors, it would soon create a copy that was incapable of replication, thus potentially ending the line of replicators. This is particularly true in the early life of a replicator, when it is a more simple molecule. There, any change could be fatal. Once a replicator has evolved to the point of our complex DNA molecules, errors in replication may have little to no effect (we have many strands of DNA that appear to contain unusued information, so changes in these strands might have no effect). However, regardless, modern DNA exhibits tremendous fidelity, as must all replicators.

2. Fecundity, or Rate of Replication

The faster a replicator can replicate, the more quickly it can spread. Additionally, the sooner it replicates, the greater chance it has to replicate before it dies or is killed. Therefore, fecundity operates in two dimensions to increase the number of replicators in the world.

3. Longevity

The longer a replicator is capable of surviving, the greater the number of times it can replicate. Additionally, increased longevity improves the chance it has to replicate. For example, the longer you live, the greater chance you have to pass on your genes to offspring.