When starting Myrmecos Blog a few years back I resolved to avoid discussing creationism. People have strong opinions on the topic, hardly anyone ever changes their mind, and when they do it’s not because they read a blog post. Plus, creationism is so free of technical substance that it’s actually rather…boring.
I’ll make an exception for ant-related creationism, though. Especially when it illustrates a salient feature of ant behavior.
This week creationist William Dembski stepped into myrmecology with a rather odd argument:
Colonies of ants, when they make tracks from one colony to another minimize path-length and thereby also solve the Steiner Problem (see “Ants Build Cheapest Network“). So what does this mean in evolutionary terms?
In ID terms, there’s no problem — ants were designed with various capacities, and this either happens to be one of them or is one acquired through other programmed/designed capacities. On Darwinian evolutionary grounds, however, one would have to say something like the following: ants are the result of a Darwinian evolutionary process that programmed the ants with, presumably, a genetic algorithm that enables them, when put in separate colonies, to trace out paths that resolve the Steiner Problem. In other words, evolution, by some weird self-similarity, embedded an evolutionary program into the neurophysiology of the ants that enables them to solve the Steiner problem (which, presumably, gives these ants a selective advantage).
What’s the trouble with Dembski’s opinion?
In assuming the ants display a programmed neurophysiology, he misses the mechanics of how ants really solve problems.
Ants find the shortest route because of three simple facts:
- Ants follow pheromone trails
- Pheromone trails degrade over time
- Short paths take less time to traverse
When two points (say, two nests, or a nest and a food source) need to be connected, ants may start out tracing several winding pheromone paths among them. As ants zing back and forth down trails, pheromone levels build up. Long trails take more time to travel, so long-trail ants makes fewer overall circuits, more pheromone dissipates between passes, and the trails end up poorly marked. Short trails enable ants to make more trips, less time elapses between passes, so these trails end up marked more strongly. The shortest trail emerges.
Here’s a simulation showing digital ants selecting the shortest of 4 possible routes. Note how and where pheromone concentration builds:
Do you see what’s going on? Individual ants do not need to be smart for a colony to find the shortest route. There’s no need for a programmed problem-solving neurophysiology, as Dembski suggests, either divinely designed or naturally selected. Rather, the solution emerges organically from the summed actions of many individuals. It’s a classic case of swarm intelligence.
In missing the point of the ant study, Dembski’s post becomes a non-sequitur.
In Dembski’s defense, his error is a common one. Ant societies share enough superficial similarities to human ones that the tendency to anthropomorphize is strong. It is too easy to assume ants solve complex problems the way we humans do, with smart individuals applying brainpower to puzzle them out. Real ant colonies are more subtle than that, their decisions arising instead from the complex interplay of thousands of individuals.