## I.4 Organisms share the evident characteristic of internal organization

Another very evident characteristic of living systems is their statistically highly improbable internal organization.This property of system is very frequently erroneously confused with complexity and, in living systems, with usefulness. This is a quite separate property of the system. If the complexity of a pile of paving stones is compared with the complexity of a paved sidewalk, it is found that the complexity of the pile of paving stones according to various criteria is greater than the complexity of the paved sidewalk. However, the organization of the sidewalk is incomparably greater than that of the original pile of stones.

We mostly have a tendency to compare the organization of a system with the level of its internal entropy or with the length of the algorithm that allows us to describe the system. While the length of the algorithm increases with increasing complexity, it decreases with increasing organization (Fig. I.8).

Fig. I.8. Complexity and organization. The paving on the left-hand part of the sidewalk in Viničná street displays greater organization, while the right-hand side is more complex. (In the spring of 2003, the city authorities substantially increased the orderliness of this system, at the expense of its complexity. It is probably now easier to walk on the sidewalk but, if it weren’t for irresponsible dog owners, it would probably be quite boring.)

This intuitive conception of organization is, however, apparently rather inexact or, at the very least, does not fully reflect the exact nature of the property that we perceive as the organization of living systems. The main attribute of the organization of the inner structure of organisms and of their individual parts is not their degree of organization but rather their statistical improbability. There exist an enormous number of ways that paving stones can be ordered in a pile. However, there exist far fewer ways in which they can be arranged in the continuous, single-layer surface of a sidewalk. When we look at a pile of paving stones, we feel no need to ask how it is possible that they are arranged in just that specific structure, one of the almost infinite number of possible structures. Almost all of the structures are equivalent, they do not differ in any substantial way. After all, a pile of stones has to have some sort of structure . On the other hand, the structure of a sidewalk is something quite unique, whether in that the stones in that specific arrangement cover in a continuous layer the smallest possible area or in that it will be more pleasant to ride roller skates over it. It is, of course, quite possible that the paving stones would form this structure purely by the chance as a small percentage of all the possible structures will have just this unique property, i.e. permit easy roller skating, but it is statistically highly improbable. Thus, it makes sense to ask what force caused the particular arrangement of stones. In the case of the sidewalk, it was probably a crew of pavers; however, if we encounter a similar structure in nature, it makes sense to consider a combination of the force of gravity, mechanical shaking and forces leading to mutual adhesiveness of the surfaces of the individual stones.

In the case of organisms, the viability of the organism and the functionality of its individual organs are a measure of their organization in the sense of statistical improbability. There are an infinite number of ways in which the molecules forming the body of an organism could be arranged to form an unviable organism or disfunctional organ. In contrast, the means of organization that form a viable organism or functioning organ constitute only a tiny percentage of the whole. Thus, it definitely makes sense to ask how it is possible that organisms exist in just those rarely occurring and thus statistically improbable states.