Little Yellow Ranchers

I found this little guy in Gander Mt. last week:

This is a Little Yellow Ant, (Lasius claviger). They are primarily subterranean, which explains the small eyes. I found this guy by rolling a log over.

Little Yellow Ant (Lasius claviger), Gander Mt. FP, Lake Co, IL 4/19/2014

Then I rolled another log, and got this shot:

Little Yellow Ant (Lasius claviger) with aphids,
 Gander Mt. FP, Lake Co, IL 4/19/2014

When I took it, I figured that the white little critters were ant larvae. When I looked at the shots later, I realized they were considerably more interesting -- they're root-eating Aphids (family Aphididae)! Why is this so interesting? Because the ants aren't eating the aphids -- they're milking them! If you look closely, you might see that there's a drop of liquid being excreted by many of the aphids. Because of their diet, this liquid is high in sugar, which makes it an excellent food for the ants. So they actually tend the aphids, guard them, and yes, even milk them!

This particular species of ant is impressive for another reason. They're social parasites. (1) In most species of ants, the females undergo their mating flight, then establish new colonies of workers that gather food for the winter. This species (and several others in the genus) fly later, so late in fact that they wouldn't be able to establish a new colony of their own. Instead, the females enter the nest of one of their congeners, kill the queen, and take over the colony. (In this particular species, females may hibernate on the surface, then enter the host colonies early in the spring.)

These behaviors (ranching and coups d'etat) are the stuff of human history -- we like to think that we used our vaunted intelligence to invent them, and that's true. But these little ants don't have any intelligence to speak of, and they managed to invent these behaviors (and others -- agriculture, slavery, etc.) despite the lack. If you have enough critters with enough variation, you can explore a very large set of potential solutions to the problems of life. It's wasteful -- most variations fail. But if you don't care about how many little ants die on the way, this method will come up with all sorts of answers.

One of the characteristics of human methods of problem solving is that we seek to understand the problem, to simplify it so that we can tell ourselves a coherent story about it. Evolution doesn't need to do this, so often the answers it comes up with are stranger and more complicated than anything we create, sometimes to the point that we can't understand them at all. And yet, they work! Typically when we can manage to work out what's going on, we find all sorts of built-in inefficiencies, leftovers from the history of the organism. But computer programmers that specialize in so-called evolutionary algorithms have demonstrated that under the right circumstances, this sort of extreme trial and error can result in solutions that outdo anything we've ever come up with ourselves.

(1) Raczkowski, J. M., & Luque, G. M. (2011). Colony founding and social parasitism in Lasius (Acanthomyops). Insectes sociaux, 58(2), 237-244.