The population died out overnight probably because of something I did yesterday. Yesterday I continued from 110623-1503 (17 MB), the next save file 110623-1855 (19 MB) has the population being a bit bigger but the population then drops off to the last save file 110624-0155 (296 KB).
My plan is to temporarily undo the changes I made regarding picking up robots that have fallen off the world and preventing those robots from reproducing while in transit. I'll continue from 110623-1855 (19 MB). I'll keep the changes to how to how long the robots have to wait till they first reproduce and can subsequently reproduce the same. The hard part is that I don't know how long I have to wait before I know that what I have done will make the population persist again.
elapsed real time: 10 seconds elapsed sim time: 5.9 seconds total real time: 1 day 1 hour 20 minutes 10 seconds total sim time: 5 hours 41 minutes 59.1667 seconds
I'll let the simulation go for another 30 simulation minutes. I suspect that there was something wrong with my code for preventing reproduction from occurring when robots are off the ground.
Hmm, even with no robots, the simulation uses 553,200 K of memory.