Thoughts Guiding Systems Corp.,

Ottawa, Canada.

e-mail:karasik@sympatico.ca

There are three approaches to tracing technological evolution. The first one is to trace the evolution of implementation of a function. The second one is to trace the evolution of a system's modifications. The third one is to trace the evolution of applications of a system/function.

TRIZ employs the first approach only. The thing is that tracing evolution means its reconstruction. And reconstruction of all modifications that a technical system went through is THEORETICALLY impossible.

Here lies the difference with biological evolution. In biology it is assumed that THEORETICALLY it is possible to trace all modifications of species, that THEORETICALLY it is possible to reconstruct the complete evolutionary tree. Such a belief is based on the assumption that all modifications were preserved in fossils. (Even if not all then at least there are no big gaps.) Sooner or later the fossils containing the missing chains will be found and the tree will be completed.

Such an assumption is not valid in technology. The patent archives contain a tiny fraction
of all modifications that systems went through. __Most modifications took place in the brains of inventors
as the intermediate steps toward their inventions. They usually do not put these intermediate
steps/modifications in writing and no trace is usually left of them.__

Thus, in case when intermediate modifications are not small,
it is impossible to reconstruct a meaningful evolutionary
tree of a technical system in the spirit of evolutionary trees of species.
__It is even impossible to identify two systems as evolutionary related.__

Indeed, suppose that inventor started with system
A_{1} and mentally modified it into A_{2}, which he subsequently modified
into A_{3}, etc. Eventually he arrived at modification A_{n}
which turned out to be a solution to the problem he worked on. He made A_{n}
public by patenting and/or building it. He never disclosed his starting point A_{1} and
the intermediate steps A_{2},..., A_{n-1}.
How would an external observer determine that A_{n} and A_{1} are
evolutionary related if the intermediate modifications A_{2}, A_{3}, etc.
are unknown to him ? It is only possible if A_{n} is still close to A_{1}.
(As was the case with cornets
for which Niles Eldredge managed to build a seemingly almost complete evolutionary tree.)
But if the sum of the slight modifications A_{2} to A_{n-1} is not slight,
then it is impossible to recognize similarity of A_{1} and A_{n} and suspect
that they are evolutionary related.

That is why studying technological evolution by building evolutionary trees did not take roots in TRIZ (and in the history of technology on the whole). Historians restrict themselves to studying either evolution of implementation of a function or evolution of application of a function. So far the latter has not been shown to be useful for TRIZ purposes, however. This explains why TRIZ restricts itself to studying evolution of implementation a function only.