DNA is not a Blueprint

Textbooks of biology repeat time and again that DNA is a 'blueprint' for building a body. It isn't. A true blueprint of, say, a car or a house embodies a one-toone mapping from paper to finished product. It follows from this that a blueprint is reversible. It is as easy to go from house to blueprint as the other way around, precisely because it is a one-to-one mapping. Actually, it's easier, because you have to build the house, but you only have to take some measurements and then draw the blueprint. If you take an animal's body, no matter how many detailed measurements you take, you can't reconstruct its DNA. That's what makes it false to say that DNA is a blueprint.


It is surprisingly hard to find a good analogy for the development of living tissue, but you can find partial similarities to particular aspects of the process. A recipe captures something of the truth, and it is an analogy that I sometimes use, to explain why 'blueprint' is not appropriate. Unlike a blueprint, a recipe is irreversible. If you follow a cake recipe step by step, you'll end up with a cake. But you can't take a cake and reconstruct the recipe - certainly not the exact words of the recipe - whereas, as we have seen, you could take a house and reconstruct something close to the original blueprint. This is because of the one-to-one mapping between bits of house and bits of blueprint. With conspicuous exceptions such as the cherry on top, there is no one-to-one mapping between bits of cake and the words, say, or sentences of its recipe.


You cannot reverse engineer DNA from the animal it appears within.

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Functions and mappings (0.912829): dbpedia
Building (0.823012): dbpedia | freebase | opencyc
Truth (0.801288): dbpedia | freebase
Kanye West (0.788131): dbpedia | freebase | yago | musicBrainz
Engineering (0.776284): dbpedia | freebase
Reverse engineering (0.744893): dbpedia | freebase
Bink (0.740444): dbpedia | freebase | yago

 The Greatest Show on Earth: The Evidence for Evolution
Books, Brochures, and Chapters>Book:  Dawkins, Richard (2010-08-24), The Greatest Show on Earth: The Evidence for Evolution, Free Press, Retrieved on 2011-05-19
Folksonomies: evolution science