First of all, I am not biologist, nor good in chemistry/physics.
Secondly, I am really eager to understand.
- So I think of a "life" (of a certain whatever being) as a space of somewhat properties. Having a wings is a property. Being tall is a property. Ability to speak as humans do is a property as well.
- Properties can be combined. Nearly like Lego blocks do combine: one can build both: a) quite elegant structures, b) total absurd of those blocks. Like with Lego, not necessarily each block can be composed with each block. There are some (probably extremely sophisticated!) rules, defining what can be combined with what; thus set of all properties you might get in future depends upon all the properties you already have. In other words, you present defines all the possibilities of your future.
- There is at least one measuring system: it takes a set of properties as an input and maps it to a, let say, number (or something else, which obeys ordering; number feels like the most simple example) denoting how "good"/"bad" this particular combination is.
- As a natural consequence of all above-mentioned, there is a directed graph, where: A) vertices represent all possible sets of all possible (respecting rules) combinations of all possible properties; B) directed edges represent the possibility to "evolve" from one concrete set of properties to another one concrete set of properties.
Based on those assumptions, I am going to define what "evolution" is:
Evolution becomes nothing but a finding a shortest path in that unbelievably huge directed graph. I assume most of the readers don't understand algorithms, so brief remark: "shortest-path" problem is one of the hardest even known; roughly saying, it takes "infinite" time and hence is impractical for humans; however, this perfectly explains why evolution takes billions of years - indeed, it's not that hard to define graph, which can't be solved faster than that.
But in order to find shortest path, which is known well from algorithmic theory, you have to be as broad as possible. You try to explore as many vertices, as possible, which means you're creating creatures with all those properties (see #2) and measure their "goodness" with help of your metrics (see #3). The problem here is that you have to track/memorize all the paths you have tried already; especially those, which are proved to be deadends: otherwise your graph exploration will never terminate: you will cycle over the routes you've seen already, but forgotten.
The other thing of great importance, is how expensive your computation is. It runs billions of years and thus you have to guarantee that it's defended properly, can't be lost because of stupid mistake or unexpected circumstances; and the best known way to do this is to copy information about entire process (since very beginning) to each and every Life-being you ever create. The more copies you got, the more reliable entire system: even if you loose all of them momentarily and exactly single creature will survive, it will be sufficient to continue your computation (to continue evolution) relying on the information it accumulates.
Taking into consideration the dimension of the graph we're talking about, that "backtracking" requires enormous amounts of memory. Hence, you need perfect compressing technique to pack your data in the most compact way. And it seems to me that DNA is exactly for this reason (probably not only for this, but this one is definitely important).
What I'd like to hear, is how logical entire thinking I've demonstrated, ignoring numerous details (which I even not aware of)? Could it work like a dramatically simplified representation of evolution? Did I define the DNA's role correctly then? Can you extend this "graph analogy" with fresh details? Am I missing something really big and fundamentally important?
Evolution becomes nothing but a finding a shortest path in that unbelievably huge directed graph.
What makes you think that evolution followed the shortest path?
Evolution does not. In order to find one, you have to try all of them (i.e. all possible paths starting from all existing vertices), measuring "shortness" according to a particular metric system you've accepted. Thus, "try them all" becomes an iteration over all possible properties in all possible ways (see #1 on the top of OP). Some of them clearly better than the other one (already known, seen in past and memorized somehow); but that does not discover the "best" path yet: there are, generally saying, unknown number of vertices you haven't visited yet, haven't measured yet, haven't tested out yet.. So, imagine you do not memorize what you have seen; what's than? What will happen if your metric system will get changed one day? - You'll have to start from the beginning rather than re-measure known subgraph (which is much more faster).
2) @Cort Ammon:
"There is at least one measuring system ... denoting how good/bad a combination is." This may be true telelogically, but we have no clear indication as to whether such a measure exists in a physical sense. Personally, I find it's more effective to think of there being at least trillions of measuring systems, each doing its own thing, which may or may not even be associated with evolution directly, such that the gestalt of all of those systems gives the behavior we see. While we can think of systems as "striving for good," we can also think of them as "just doing their own thing." Both approaches model nature quite well, with their own quirks.
I can't agree with you here. Having any positive number of metrics does not contradicts to the statement "there is at least one"; as well as having a "superposition" of any positive number of metrics does not.
So what we end up finding is that your definition is akin to saying "A written language is nothing more than a construct which admits finite sequences of letters".
Exactly. What I am saying, is that there exists an enormously huge graph of all possible combinations of all the letters. If you allow you letter sequences to be infinite, than graph itself becomes infinite as well; however, since it takes place in Nature those must be physically limited like everything else. Some of those letters indeed unite into words, which do make sense; the other sequences are just nonsense (with respect to the given metric system: hence, there might be cases, when one metric system disagrees with another one, it's OK). Then evolution becomes a process of searching for the greatest novel ever written (once again, according to the preferable metric system - even if it itself is some kind of "summary" of millions/billions/trillions of factors we're not aware of).