Thursday, March 12, 2009

101 Interesting Things, part nine: Agricultural Insects

Ecclesiastes 1:9 states, "What has been will be again, what has been done will be done again; there is nothing new under the Sun."  Ununoctium notwithstanding, this holds true in a very important sense for just about any bit of human existence you could care to point at.  By and large, our customs and beliefs are handed to us from our predecessors, who in turn got them from their predecessors, and so on.  Though there has been bitter competition in the meme pool, there is a fairly good record to track, in the form of the historical record, when it comes to finding out where ideas come from - not all the way, of course, but a good ways back in a lot of cases.  Tracking the history and development of ideas (or "memetic pedigree," if you will) can be a very interesting enterprise.

One may experience similar fascination by seeing a human invention anticipated by nature.  The taming of fire, so far as I know, is the only respect in which humanity stands out from the rest of the animals (and all the developments obtained thereby, such as metal, and all the neat things we need metal to do, like build particle accelerators).  Two other biggies are the wheel and the domestication of other species.  But the wheel finds its answer in the bacterial flagellar motor, which anchors the rotating flagellum to the cell wall in a housing that incorporates a free-spinning disc.  As for domestication, that is what this post is about.

Our main example for today is the leaf cutter ant, which has domesticated a fungus.  As Richard Dawkins writes in The Ancestor's Tale:
A single nest of leaf cutter ants, Atta, can exceed the population of Greater London.  It is a complicated underground chamber, up to 6 metres deep and 20 metres in circumference, surmounted by a somewhat smaller dome above ground.  This huge ant city, divided into hundreds or even thousands of separate chambers connected by networks of tunnels, is sustained ultimately by leaves cut into manageable pieces and carried home by workers in broad, rustling rivers of green.  But the leaves are not eaten directly, either by the ants themselves (though they do suck some of the sap) or by the larvae.  Instead they are painstakingly mulched as compost for underground fungus gardens.
The ants treat their fungus crops just the same as we treat our own garden veggies:  planting them, tending them, keeping them free from pests, and finally eating them.  Termites do largely the same thing, as it turns out - we even run up & steal their stuff 'cuz it's tasty.  And some ants go one farther, herding aphids like cattle.  So much for domestication.

So it looks like we're down to fire as our last defining difference.  Once some other species gets a hold of that, it's a hop, skip, and a jump to smelting alloys and making large hadron colliders.  Geologically speaking, of course.  I mean, we got from there to here in a measly million years or two.

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