Wednesday, 9 November 2011

Uncopyable heredity

One of the deepest classification divisions in the science that studies heredity is the split between things that can be copied, and things that can't be copied.

Everyone is familiar with heritable elements that can be copied. DNA genes and memes fit this description. However, there are also things that persist across the generations that can't be copied. Ming vases, for example, are inherited down the generations - but attempts to copy them create items which are worthless. Brains are another item which persists across multiple generations (for example, my grandmother's brain still exists) - but cannot yet be fully copied. Fingerprints can't be fully copied either and nor can retinal vein patterns. Nor can I copy my mother. There are numerous other examples.

Uncopyable heredity is the less interesting kind. Heredity without copying is less common and it doesn't result in cumulative adaptations. However, it is essential for properly understanding evolution.

The division between copyable and uncopyable heredity elements is not necessarily a fixed one. Once we could not copy music very well - and now we can. Progress results in more things becoming copyable.

However, split between things that can be copied, and things that can't be copied still seems to be pretty deep and fundamental. I think we need terminology to describe copyable and uncopyable heredity elements.

Dawkins proposed the term "replicator" for heritable elements that can be copied. In his 1982 book, "The Extended Phenotype" he defined the term, as follows:
I define a replicator as anything in the universe of which copies are made.
Blackmore (1999, p.5) endorses this definition, saying:
A replicator is anything of which copies are made
However, the term seems to have led to much confusion among scientists, and we have multiple rebuttal papers claiming that replication is not necessary - for example, this one: Why replicators are not necessary for cultural evolution.

On one hand this seems to be obviously a misunderstanding - the critics are not paying attention to the definition that Dawkins is using - but on the other hand, the terminology Dawkins proposes does invite this kind of misunderstanding.

As I have explained in my video/essay Against Replicator Terminology - and also in my book - the replicator terminology has some serious issues - and should probably be abandoned.

However, this would leave a terminological void. What we really need is replacement terminology to refer to copyable and uncopyable heredity elements.

There is the term "reproducer". This is the solution proposed by Griesemer (2000a, 2000b) That term is rather overloaded - but it seems to be one of the best terms we currently have for copyable heredity elements.


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