Instruction Manuals and Genomes March 18, 2012Posted by Ubi Dubium in Parables, Rants.
Tags: biology, creationists, Parable
I recently had a Fundie say this to me in a comment on another blog:
“Of the 5,000 best-known human genes, 75% have matches in the worm (see “A Tiny Worm Challenges Evolution”). Does this mean that we are 75% identical to a nematode worm?”
Then he also said “Theoretical(sic) a worm has 75% of your brain”
Really. Yeah, apparently the hard-core creationists really teach their sheep to say stuff like this. I gave him a quick answer, but over the next few days a new Parable started rumbling around in my head. With a little assistance from UbiDubiKid#2 on some of the details, here is:
The parable of the Instruction Manual.
If I went to a builder, “How do I build a nice large house?” I might expect his response to be to pull out a set of blueprints. If I asked “how can I build a small townhouse?” he’d pull out a different set, and the blueprints for a mansion or an office building or a shopping mall would also be different. At first glance, these plans would not resemble each other very much at all.
But the blueprints are actually only a tiny part of the information needed to build a house. To really know how to “build a house from scratch” you would need to turn to the Complete Instruction Manual on House Building for that house, which is a multi volume set.
Volume 1, Lumber, has instructions for cutting down trees, which kind of wood is good for what kind of use, what size boards should be used, how to frame walls and doorways, how to do fancy woodwork, and anything else having to do with wood.
Volume 2, Bricks, has instructions on selecting clay, making different kinds of bricks, and firing them. It has instructions on how to lay bricks, and a long section on the manufacture and use of mortar.
Skipping to Volume 27, Hand Tools, we find chapters on how to make all types of hammers (with cross-references to Volume 1, Lumber, and Volume 13, Iron Smelting for the materials). Additional chapters have instructions on screwdrivers, saws, and drills. Volume 28 continues with Power Tools.
Other volumes discuss the manufacture and installation of wallboard, wiring, plumbing, concrete foundations, etc. Two large full volumes concern construction vehicles, one on manufacture, and another on use and maintenance.
In each Complete Instruction Manual on House Building, the specific blueprints take up only a few pages. Most of the rest is pretty much identical information, regardless of what kind of building you are constructing. Sure the Manual for stately homes may have more about marble quarrying, but most of the information is the same.
The human genome is a lot like that. Most of the information on how to build an organism is about assembling the required proteins to build all its different cells, and other information keeps the cells running and functioning together. Only a small part of the genome is devoted to how many of each type of cell there are, or how they are arranged, or how to grow the complete organism from a singe cell, the part we might call a “blueprint”.
Since the c. elegans worm that the fundie was talking about is an animal, made of eukaryotic cells of various types, as we are, since it moves and eats and breathes, as we do, we would expect it to be made out of the same basic stuff and share most of its Complete Instruction Manual on Organism Building with humans. As it does.
Except, if the Complete Instruction Manual on House Building were really like our genome, you would find a few surprises on reading it. For instance, the chapters would not be in a neat logical sequence, but scattered about and broken into pieces. The chapters on Nails, for example, would be broken up and scattered in with Heat Systems, Carpet Manufacture, and Paint. For some reason, all the building manuals would still include instructions on wattle-and-daub wall construction and thatch roofs, even though nobody builds those any more. (Those instructions are full of accumulated typos, anyway, and impossible to make out completely.) For some reason there are whole pages of gibberish, including pages that say nothing but the word “toothpaste” repeated over and over again. Sometimes those gibberish pages fall in the middle of important instructions. And there are sections full of casserole recipes, and a list of video game cheat codes, which appear to be totally irrelevant.
Since we are made of the same stuff, it would be astonishing if we did not share most of our genome with worms, or any other animal for that matter. Trying to twist this into a reason to reject evolution is intellectually dishonest, and that’s the politest way I can put it.