One of the things I learned in my Ecology class is that Mother Nature is not a bitch. She's a nasty, vicious, sneaky bitch. The kind of competition that goes on in nature would not be allowed by the Geneva Convention.

Things like poisoning the ground (as black walnut trees do), replacing your enemies children with your own (as cowbirds do) and just plain eating the young of your competitor (as just about everything does) is not allowed in human conflict. (Luckily, eating other mammals is allowed. We're not at war, so it's OK. )

But, as Darwin pointed out, if a species doesn't do better than the other species at utilizing its niche, another species will displace it and take over that niche.

And, thus the iRobot Roomba E6 joins the dodo, the passenger pigeon and the brontosaurus on the scrap heap of evolution.

The RoboRock stealing the Roomba's invisible walls was a trick right up there with monarch butterfly caterpillars eating milkweed to concentrate toxins that they're immune to in their body. The poor Roomba kept wandering into foreign, unknown spaces and being trapped under a sofa or just starving to death.

After a few days of playing "You'll wonder where the roomba went," I powered down the Roomba and delegated it's area to the RoboRock.

A weakness of this model Roomba is that the only way to control where it goes is with the invisible walls. I've been running two Roombas, one that does one part of the house, and one that does the other while I sleep. Every few days, I'd take one into the bedroom to clean there.

With the RoboRock's mapping, I can have it do everything except my bedroom during the night, and do the bedroom during the morning when I'm working at the other end of the house.

There are Roomba models that do mapping like the RoboRock, but I don't feel the need to buy yet another cleaner when I've finally gotten one that can do the entire upstairs.

Doing the entire upstairs every day means not stepping on kitty crunchies from the litter box when I finish my shower. This is a good thing, IMHO.

And, as you might expect, the day I powered off the Roomba is the day that the RoboRock tried to eat a USB cable and then chowed down on a dog toy.

Being the winner of the survival-of-the-fittest contest does not require that winner is actually fit. It just requires that one is better than the next worst.