https://barryhisblog.blogspot.com/p/genetic-information.html
We often see creationists and intelligent designer spotters asserting that evolutionary processes cannot increase what they call "information" in the genome.
The assertion runs up against Hitchens' Razor, "What can be asserted without evidence can also be dismissed without evidence", but the assertion is interesting to examine in a little more depth.
How do such people envisage genetic "information"? (I'll drop the scare quotes from here on, because it gets tedious and irritating, but take them as read.) How it is quantified is never considered, but you cannot sensibly talk about any quantity increasing or decreasing if you do not have a sensible way of actually quantifying it.
Yes, you can simplistically quantify DNA information by considering it as a base four number. Just like binary or base two has the two symbols, 0 and 1, and base ten, or decimal, has ten symbols, DNA can be described, by us, as a base four number by using four symbols, A, C, G and T that we have assigned to the chemical bases.
But in what sense can a number, in whatever base, be said to embody information? Surely the context or function of the number comes into things. A string of numbers is just a meaningless string of numbers until it comes to be applied in some way. Similarly, a gene for a protein, a string of base pairs, only means something when RNA polymerase transcribes it and a ribosome translates it into codons for amino acids. If such a process doesn't happen, (for example, the much publicised ENCODE project that found a vast number of RNA transcripts that are never translated (though some of them may perform other functions)), that string may then be either vital or irrelevant or even fatal, depending on the context in which it exists.
How do such people envisage genetic "information"? (I'll drop the scare quotes from here on, because it gets tedious and irritating, but take them as read.) How it is quantified is never considered, but you cannot sensibly talk about any quantity increasing or decreasing if you do not have a sensible way of actually quantifying it.
Yes, you can simplistically quantify DNA information by considering it as a base four number. Just like binary or base two has the two symbols, 0 and 1, and base ten, or decimal, has ten symbols, DNA can be described, by us, as a base four number by using four symbols, A, C, G and T that we have assigned to the chemical bases.
But in what sense can a number, in whatever base, be said to embody information? Surely the context or function of the number comes into things. A string of numbers is just a meaningless string of numbers until it comes to be applied in some way. Similarly, a gene for a protein, a string of base pairs, only means something when RNA polymerase transcribes it and a ribosome translates it into codons for amino acids. If such a process doesn't happen, (for example, the much publicised ENCODE project that found a vast number of RNA transcripts that are never translated (though some of them may perform other functions)), that string may then be either vital or irrelevant or even fatal, depending on the context in which it exists.
It appears that genetic information, or indeed any form of information, on its own, is not a very useful concept. It is virtually meaningless when isolated from its context. Biological fitness is always evaluated with reference to the environment - how well adapted an organism is to the environment in which it finds itself. The environment can change, so the fitness value of any feature can change with it. Thus fitness, and not the quantity of genetic information, is the key to understanding the evolutionary principles. Indeed, even a reduction of information can increase fitness.
So what about this business of evolution being unable to increase information? Have these people not heard of back mutations, where genetic changes can be reversed? What about fixing pseudogenes and other genetic defects and diseases? What about horizontal gene transfer and the endogenization of retroviral genetics? Can these not add information by adding to or fixing genetic material, given that, in principle, biological processes can produce, by genetic changes, any DNA sequence imaginable? Do they believe that every single organism possesses the maximum possible genetic information despite the differences between them and despite any genetic defects?
They haven't thought this through.
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