Darwin’s Lego Blocks

If you look at evolution from other than the perspective of an ideological warrior who believes that he is saving the world from the claws of snake-handling primitive Christians in North Carolina, difficulties arise. Chief among these is the sheer complexity of things. Living organisms are just too complicated to have come about by accident. This, it seems to me, is apparent to, though not provable by, anyone with an open mind. — Fred Reed, “The Bugs in Darwin”

In an excellent essay, the often irascible and always interesting Fred Reed  points out some apparent inadequacies of evolutionary theory. Among other arguments against Darwinian orthodoxy, he cites the classic metaphor of shaking a bag containing the components of a watch in the hope of eventually assembling a working device. Such an outcome is extremely unlikely, no matter how long you shake the bag, thus proving, say the anti-Darwinists, the need for a Watchmaker.  A living cell is vastly more complex than a mechanical clock, so its assembly from random processes must be even more improbable. This argument has always struck me as weak, because the parts of a watch have few innate proclivities and are, in this respect, unlike molecules which will indeed combine with others given sufficient time, numbers, and conditions. Here is, I think, a better thought experiment to demonstrate how evolution on the molecular scale is plausible:

Place 10,000 Lego bricks in a cement mixer and set it to mixing.  As the bricks tumble and collide, some will accidentally join. Most of these joints will be simple and weak, with only one or two pegs engaged on each brick; these weakly bound Lego “molecules” will be short-lived. More rarely, four pegs will engage to form more strongly bonded units that last longer and may engage additional bricks to grow in complexity.

The strongest bond will be one in which two Legos join squarely, with all eight pegs engaged. This is rare but almost inevitable, and when it happens it will likely lead to even more growth and complexity as collisions  hammer the blocks more tightly together. Ultimately, one can imagine short towers growing and even “reproducing” by fission when they get too long. Decanting the cement mixer will likely reveal many species of structures, with the “fittest” being most numerous. One could be forgiven for concluding they were manufactured consciously.

Darwinism requires planet-sized cement mixers and far more sophisticated Lego bricks to plausibly invent self-replicating molecules but it is not an obviously unlikely process. What has always struck me as problematic is not the construction of living things, but what they do. Fred agrees:

Consider the Tarantula Hawk, a gigantic wasp that begins life as an egg inside a paralyzed and buried tarantula, where its mother put it. This may seem unmotherly, but there is no accounting for taste. The egg hatches. The larva feeds on the spider, somehow knowing how to avoid the vital organs so as to keep the monster alive and fresh. It pupates and then, a new adult, digs its way out of the burrow.

He goes on to point out the many implausible links in the chain from one wasp generation to another, how a wasp who has never seen another wasp must find a mate (“a rather more complex process than it may seem to high-schoolers”), locate and recognize a tarantula, etc., in order for the species to continue.  Break one link and the species ends. He concludes “There is Something Else involved. I do not know what.”

Nor do I. The notion that a cloud of hydrogen will spontaneously compose a symphony after 14 billion years strains credibility. “Emergent complexity” is a pretty phrase that seems a lot like hand-waving. DNA might contain sufficient information to build a tarantula wasp, but is there enough information to tell the resulting organism how to be a tarantula wasp? It seems this should be testable, at least in theory: write a program to model the behavior of a simple organism and then see if its DNA, less the weight of the construction blueprints plus known garbage genes, could theoretically encompass the instruction set.

Short of that, the reductionists could, perhaps, isolate the segments of a mockingbird’s  DNA that encode its song .

I’d love to see if Lego evolution via cement mixer is possible. Such a demo could be a fun art piece for Burning Man.

Update, November 27, 2014. A team has modeled at least one aspect of the behavior of a tiny worm using Lego motors and a neural network.


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