Evolution as an Algorithm

In his book, Darwin's Dangerous Idea, Daniel Dennett outlines the idea that evolution is an algorithm, similar to a computer program. That is, it is a sequence of steps (reproduction with variation then selection) that reliably produces a particular result (evolution). He shows that algorithms are independent of the substrate they run in. For example, some computer programs use the evolution algorithm for design work.
If one can show that the description of the evolution algorithm is correct and if one can show that biological systems do exhibit reproduction with variation, and that selection operates, surely one should then expect evolution to occur. If these requirements are satisfied, is that sufficient for confidence in the ToE?

---

Don

Perhaps I was not quite clear. One way of looking at an algorithm is as a "black box" that, if presented with proper inputs, produces a particular output. In the case of evolution, it seems to me the proper inputs would be a) any kind of object that exhibits reproduction with variation and b) some kind of selection rule. The output would be changes in progeny (over time) that accommodate the selection rule, ie evolution.

I am not suggesting the use of a computer model here. The argument would run something like: If the algorithm is valid (ie reproduction with variation plus selection yields evolution), then if any system exhibits reproduction with variation, we should expect evolution in the presence of selection. One would still have to verify that the algorithm is correct and that any system of interest does exhibit the required behaviour, reproduction with variability.
Questions such as the scope of the changes etc are another matter, and likely much more interesting.

nwr, thanks for your response. It would be pretty dull if everyone just said "of course". I would like to ask you to expand on a couple of your comments. I had looked at some definitions of algorithms and they seemed to me to fit; what might I have missed? Also, I don't see how evolution being an algorithm validates the "prescribed" hypothesis. I admit to having had only a brief look at that. Please fill me in.
I rather liked the book, although I found it a bit unfocussed and Dennett's constant posing of questions without much follow-up is irritating. I was quite struck with the algorithm idea and also the idea of a genomic space and paths in it.

Interesting posts. I would ask about two things. What is this "brick wall" that I see mentioned here and there. Also, I don't see why infinite (!!) variability should be needed. The chemistry would rule that out, if nothing else, but a good deal of variability might go a long way.

Very nice and clear. I wonder if we could look at evolution as a sort of nested algorithm? That is, repeated cycles of reproduction-with-variation-plus-selection, with the output of one cycle feeding the next and change in the selection rule from time to time. Would this provide the interaction you desire? That way the system could track whatever it is that is governing the selection rule.
It just struck me that one could, and in biological systems probably would, have more than one selection rule operating at the same time. There seems to be lots of room for complexity here, even if the mechanism is relatively simple.

I see no reason why the items you quote from AiG could not be included in a program quite easily. The fact that some programs do not do so does not show that none ever could. I find that argument very fishy indeed.You seem to assume that some large fraction of variations must be viable. I do not see why this should be so. A line I like from Dennett's book goes: "Evolution depends on events that almost never happen.".I gather that you see some flaw in the overall evolutionary algorithm or process or whatever we might like to call it. Would you care to describe it?

I'd just like to correct an impression I see here. The original post was not meant to ask if evolution could be modelled on a computer. My concept of an algorithm was that of a well-defined set of operations that could be relied on to process its inputs to yield its outputs in the same way every time. My interest is in an idea that, if evolution works in that way, and biological systems meet the requirements for a proper input to the algorithm, we can confidently expect evolution to occur and so be able to focus our attention on the details.
It is convenient, and fun, that we can indeed model evolution using computers, but that is not what I was trying to get at.Best regards

---

After all, comfort can be just about anything, provided you need it enough at the time. Grey Owl

I agree, we agree quite well. I was not trying to refute you at all.

Oh, yes, quite right. Sorry.