Turning on Organism Facing in replication

By default, organisms' offspring are placed randomly in one of the cell connected to the parent. The BIRTH_METHOD option in avida.cfg allows the user to change the default method by which organisms are replicated. Our first step in allowing organisms to choose the placement of their offspring is the set BIRTH_METHOD to 7 ("Organism faced by parent").

Try running Avida with this setting in place.

You should see that nothing much of interest happens (only two cells are ever occupied), and the run as a whole ends quite quickly. This is because the parent never turns so its always replacing its offspring, and an offspring is always born facing its parent.

Clearly, in order to get this to work we need to give the organisms the ability to rotate. To do so, go into the instruction set file and add on the new instructions "rotate-l" and "rotate-r".

Try running avida again.

Most likely you had a similar result to last time. While the organism now has rotate instructions in its set of possible instructions, it still does not possess the ability to rotate. We have two options now:

1. Keep trying until an organism happens to get the right mutation and can rotate before replicating.
2. Modify the ancestor to have a rotate built right in.

Surprisingly, either option will work just fine. For fun, lets go with option 1. About one in ten times you'll see the self-replicator take off in Avida in the population. You should see some very interesting patterns form, very different from a typical Avida run. Pause Avida and see if you can figure out what's going on with the organisms and their facing.