Most generally, adaptation
is the process by which a set (population) of reproducing and decaying systems (e.g., organisms) of a given kind selectively change in response to current externally sourced influences.
The process of adaptation in biological organisms has been understood, and fully reduced to everyday practice for most of recorded human history (thousands of years).
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Adaptation Is Not Darwinian Evolution
There is currently a great deal of obfuscatory pressure on the language, which makes it easy to inadvertently conflate the word: adaptation
with the word: evolution
(or, to conflate adaptation with the term: "Darwinian evolution").
Clear discussions of the mechanisms underlying memory
may require the use and conveyance of a precise, non-ambiguous meaning of the word: adaptation
. For this reason, the word—in its original meaning—needs to be reclaimed.
In biology, evolution is the notion, first posited by Alfred Wallace
(and subsequently promoted by Charles Darwin
), that adaptation has led to the emergence of new species, which comprise all the known species in existence today.
The concept of adaptation within
species, however, had been fully understood and used for many thousands of years before Wallace's evolutionary concept had been documented, and promoted. In fact, adaptation had been so thoroughly understood previously that it was reduced to everyday practice by many farmers and other regular folk. It was also codified in a variety of ancient texts and religious books.
Part of the confusion surrounding evolution may stem from the logical relationship between "adaptation" and "evolution", which appear to merge when the concepts are used in verb-form. Here are two statements, which may help to separate them:
- Something that is "evolving" is (generally speaking) also adapting. However,
- something that is adapting is not necessarily evolving.
Put another way:
Relaxed (street) meanings
- Something that is "evolving," in the Wallace sense, must (generally speaking) be adapting. However,
- something that is adapting need not be evolving.
Another issue is that—based on the assumption that Darwinian evolution will eventually be found to be correct—it has become common to speak of all adaptive, and selective-adaptive changes in biological organisms as though they were simply part of the larger, over-arching process, which is evolution as Darwin and Wallace described it. So, for example, a bacterium is evolving a drug resistance.
It has also become popular to apply the term to all sorts of adaptive changes, re: "the airplane has evolved into the modern day jumbo-jet," or: "Though a rookie football player, one can see that he is evolving into the go-to weapon for his team."
None of these usages, or their implicit definitions for the term, are incorrect. The problem comes about when these meanings are conflated with the rigorous meaning of evolution, as it is defined and used in Charles Darwin
's book. That is, a mechanism by which all new species begin, which depends on the (long understood) mechanisms of selective adaptation as its primary causal process.
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Adaptation In Netlab
In Netlab, the term adaptation is used to denote any change to a system or system component which alters how the system responds to specific stimuli in the future, and which occurs in response to
(i.e., which is caused by
) externally occurring phenomena. Adaptations may include the mechanisms of selective adaptation, which may occur over successive iterations of a given kind. They may also be adaptations to intrinsically adaptive mechanisms, such as changes made to connection strengths
in traditional ANN
Many different specific mechanism are provided in Netlab to effect adaptation. For example, neurons
in Netlab include adaptive inputs
, which accept Axon Levels
that are used to alter (adapt) connection-strengths within the neuron. Neurons may also use Chemical Influences (CI
s) to alter connection strength
s directly, or affect how other mechanisms alter them.