Richard Dawkins idea on scaffolding from silicates to carbonates

In his book The Blind Watchmaker, Richard Dawkins puts forward the idea of scaffolding which helps explain the apparent lack of a complete historical record for the evolution of carbon-based lifeforms.

He says that quite possibly silicate equivalents of RNA replicators may have started from clays which were plentiful on the early Earth. Silicon is an element similar to Carbon in that it offers the opportunity to combine with other elements such as Hydrogen and Oxygen to form myriad compounds. Life is carbon-based now, but perhaps it was Silicon-based on the early Earth. Yet there is no evidence of Silicon-based life now.

Dawkins uses the idea of building an arch of bricks or stones to illustrate why the lack of Silicon-based life is actually to be expected (rather than an argument against evolution and natural selection).

An arch is a strong and elegant structure, very useful in building. It is inherently self-supporting - but only when it is complete. If you were to build an arch for a doorway or a larger structure like a bridge, perhaps even a building such as a vaulted gothic church, it seems almost impossible to imagine how to go about it. How do you support the structure prior to it being able to support itself?

The answer is obvious when you see it - as you do when any modern structure or building is being erected. A scaffolding supports the structure as it is being built and then removed upon completion, leaving the structure to support itself.

However the answer is not obvious at first if the building or structure is very old. Well-known examples here include the Pyramids and Stonehenge. Looking at the megalithic Stonehenge lintel stones some 20 feet in the air, people have for centuries marvelled at how the early Britons could have lifted them some 4 thousand years ago. Yet if you imagine ramps of earth being built up to that height and then dug away to normal soil level afterwards - a soil scaffolding - then clearly we can so no need for magic or alien help.

Carbon-based RNA and DNA is a very complex structure now, and we marvel at how it could possibly have evolved. We question why we can't (easily) see evidence of early forms. We particularly question how the process of carbon-based life-forms' evolution and natural selection could have started given the basic ingredients available on early Earth.

What we miss, or perhaps don't think about, is the scaffolding upon which this process was constructed and which has since disappeared because it is no longer needed. The structure of RNA/DNA is here now and can support itself through its replication ability. Genes have outgrown their scaffolding - whatever that might have been - and displaced it.

Dawkins suggests the scaffolding might have been Silicon-based replicators occurring in natural clays, and builds a plausible argument for it. He even notes that in the modern world a new life-form may be emerging. We are now developing Artificial Intelligence and sophisticated robotics to the point of having the ability of self-replication. Modern computer viruses are an example, as are some cryptographic algorithms.

It seems, he muses, that Silicon-based life forms may be returning - but will they displace us Carbon-based life-forms as our evolutionary ancestors displaced the early Silicates?

Richard Dawkins on religion and Darwin

Richard Dawkin's book the Blind Watchmaker is a brilliant read - a well-constructed argument supporting Darwinian theory and refuting spiritual/supernatural religion. His explanation of Darwin's natural selection idea is clear and informative, allowing many more ordinary people to understand just what Darwin was actually saying (rather than what many have interpreted he said).

This book really helps "independent thinkers" (I'd rather not use the terms "atheist" or "agnostic") stand their ground in ordinary conversations with those who support religious views. It exposes both the fundamental weaknesses in pro-religious arguments such as creationism, and also how scientific thought (including Darwin's theories) has been mis-construed and made to appear as if it could support religious concepts.

The 1986 book is a little dated now but still highly recommended.

Other links:
http://en.wikipedia.org/wiki/The_Blind_Watchmaker
http://del.icio.us/search/?fr=del_icio_us&p=blind+watchmaker&type=all
http://www.youtube.com/results?search_query=richard+dawkins+blind+watchmaker&search=Search
http://www.amazon.co.uk/exec/obidos/ASIN/0141026162/ref=nosim/dannyyeesbook-21