Seven Clues To The Origin Of Life, A. G. Cairns-Smith

c. 1985

Preface: Glasgow, Spring, 1984

Chapter 1: Inquest

Chapter 2: Messages, Messages

Chapter 3: Build Your Own E. coli

Chapter 4: The Inner Machinery

Chapter 5: A Garden Path?

Chapter 6: Look At The Signposts

Chapter 7: A Clue in a Chinese Box

Chapter 8: Missing Pieces

Chapter 9: The Trouble With Molecules

Chapter 10: Crystals

Chapter 11: The Clay-Making Machine

Chapter 12: Gene-1

Chapter 13: Evolving By Direct Action

Chapter 14: Takeover

Chapter 15: The Seven Clues

Appendix 1: Units for DNA and RNA

Appendix 2: The Kaolinite Layer

Glossary

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The origin of life is a Holmesian problem: if we understand how life could have started at all, then we should be able to work out, roughtly at least, how it did start.

Chapter 1: Inquest

Fundamental idea of biology: evolution. "Biology has become, quite simply, the study of the causes and efffects of evolution, and the question of the origin of life is, first, the question of the origin of evolution."

Life: a trace of 'magic' can be held unto. "There is a temptation, in any case, to suppose that if the origin of life was not actually supernatural it was a statistical leap across a great divide."

"Natural selection" is only one component of the mechanism of evolution."

"Nevertheless, natural selection has been the key component, the sine qua non of evolution."

"Life is a product of evolution."

"We must find things that can evolve but have not yet done so."

Organism: another word that can be placed in the context of evolution: organisms are participants in evolution. For our purposes, organisms are prerequisites for evolution.

"Those first evolvable things that we have jut been talking about would not yet have been 'living' -- but they would still have been organisms. 

[A definition of "a living organism": something capable of reproducing and evolving by natural selection.]

The gap between the non-living molecules and the simplest bacterium was once thought (mid-1950's) to be very narrow. Cairns-Smith says the gap is now known to be "enormous."

Three Prime Facts

• First fact:  there is life on earth
• Fact two: all known living things are at root, the same
• Fact three: all known living things are very complicated

Complexity seems to be necessary to the whole way in which organisms work.

Life may in fact have had a supernatural beginning, but to come to that conclusion, all non-supernatural possibilities must be eliminated.

Chapter 2: Messages, Messages

Messages are what is passed on from generation to generation, not products.

I have trouble following this summary statement:

"If life really did arise on Earth "through natural causes" then  is must be that:

• either there does not, after all, have to be long-term hereditary memory for evolution,
• or organisms do not, after all, have to be particularly complex.

Chapter 3: Build Your Own E. coli