So I’m sitting at the bus stop a couple of days ago, and I feel a tickle on my foot (exposed in a Birkenstock sandal). Reflexively, I lean down and brush at the tickle; this swipes an ant off onto the ground. The ant starts to scurry away, but is obviously running with effort. When I look more closely, I see that one of its (her?) legs is messed up, presumably as a result of my brushing action.
I consider stepping on the ant, as I don’t imagine there’s a lot of room in a bug-eat-bug world for a crippled competitor. But as I watch, the ant’s gait smooths out a bit, and it picks up speed; apparently it’s “figured out” how to run on its bum leg, at least well enough to escape immediate danger. So I let it go.
Many thoughts followed, and, ultimately, this thread.
The basic question: How widespread, and effective, are healing faculties in more primitive critters?
I know as a pet owner that cats will go to great lengths to hide their distress, because they don’t want to appear weak and make themselves targets for predation (or of stronger cats). However, given time and rest, they will eventually recover from illnesses and wounds. Further down the scale of primitiveness, starfish can grow a new leg, and crustaceans, new claws. Trees will pitch over a gouge, and eventually fill it in, but usually there’s a scar. And so on.
(By the way, I know that “primitive” isn’t a strictly meaningful term, and can’t be measured on a linear scale. Organisms are either adapted for their niches, or they aren’t; one can’t really say, between a lemur and an osprey, which is “more advanced.” Still, I think there’s a useful lay perception ranking exoskeletal animals beneath reptiles, and mammals above both. So go with the informal sense of the term.)
It seems to me that in the world of the ant, if you lose a leg or an antenna, you just plain aren’t much good to the hive. Not only can you not contribute as much to the hive as an intact ant, you’re also slower and less able to react, which makes you more likely to get et by a bird or a spider or whatever. If ant lives are cheap, damaged ants are worth even less.
So in that kind of world, wouldn’t natural selection gradually whittle down the organism’s capacity to recover from injury? If the ability to heal offers no real survival advantage, and if the energy necessary to build the biological tools necessary to heal would therefore be better spent in areas more likely to do the organism some practical good, doesn’t it make sense that natural selection would tend to sacrifice the former for the latter? If that’s true, for which types of organisms would it apply? Ants and flies? Bacteria? At what level of development does the ability to heal become meaningful?
Or, in short: Should I have stomped the ant?