Posts Tagged ‘John Horgan’

‘Focus’ Magazine on the ‘Dawn of Life’

March 16, 2008

There’s an interesting item over at Atheism Sucks at http://atheismsucks.blogspot.com/2008/03/john-horgan-in-beginning.html on an article the science journalist John Horgan wrote some time ago on the problems of current theories on the origin of life.  Five years ago in 2003 the British popular science magazine, Focus, also did a feature on the origin of life by their writer, Robert Matthews. This covered the famous Miller-Urey experiment, various extremophiles such as Deinococcus radiodurans, a bacterium discovered in 1956 by the American microbiologist Arthur Anderson that can survive levels of radiation that will kill a human instantly, and four of the major figures in the discussion of the origin of life. These were Anaximander, who considered that life had spontaneously emerged from mud to produce fish, and then every other creature when the fish moved onto dry land; Leeuwenhoek for his discovery of microscopic creatures, confirmed by Hooke; Louis Pasteur, for proving that spontanous generation did not occur and that disease was caused by germs passing from organism to organism; and Oswald Avery, Colin MacLeod and Maclyn McCarty. The article credited Avery, MacLeod and McCarty for showing in 1944 at the Rockefeller Institute in New York that ‘a simple molecule called deoxyribonucleic acid – or DNA – found in the nucleus of living cells is the key to life’ for carrying the genetic instructions for organisms to reproduce themselves. 1 This is quite remarkable, given the way that Crick and Watson’s work on DNA is usually mentioned to the exclusion of all the other researchers. It also included a brief interview with Graham Cairns-Smith, one of the foremost researchers on the origin of life. It also briefly discussed Dr. Freeman Dyson’s theory that life evolved twice. It also included a brief overview of ‘seven of the most popular theories currently being debated’ – the RNA world, primordial soup, life from clay, PNA theory, hydrothermal vents, panspermia and Creationism. These overviews were just a paragraph long, though the piece on the Miller-Urey experiment, ‘A Landmark Experiment’, ran over four pages. 2

The Miller-Urey Experiment

The article was certainly not pessimistic about the possibility of discovering the origin of life. While it stated that ‘as a demonstration of how to create life, Miller’s experiment could be dismissed as a heroic failure’ it considered that ‘its real significance lies not in results, but in its approach. For millennia the solution to the mystery of the origin of life seemed beyond reach. It was Miller who brought it into the lab – a nd began one of humanity’s most exciting scientific quests.’ 3 Nevertheless, the feature noted the same problems with the theories as John Horgan. Although Time magazine declared when Miller and Urey’s results were published in Science in 1953 that ‘If the apparatus had been as big as the ocean, and if it had worked for a million years instead of one week, it might have created something like the first living molecule’, the results were not nearly as good as was believed. 4

The article notes that while the experiment did create six types of amino acid, only two – glycine and alanine – had any known relevance. As for amino acides, while they’re life’s building blocks, by the 1950s they were, as merely constituents of proteins, far from ‘living molecules’ and had lost their status as the master molecules of life to DNA. Specifically, they were not self-replicating, a key feature of any ‘living molecule’. Miller did not produce any DNA, nor even the A, C, G and T nucleotides. ‘As Miller himself acknowledged, the chemicals produced were as far from life as a pile of bricks is from being a humming metropolis.’ 5 Instead of the reducing atmosphere of hydrogen, methane and ammonia, astronomers instead theorised that the atmosphere on the early Earth was probably composed of nitrogen, carbon dioxide and water. Any methane and ammonia was probably destroyed by the light of the primordial sun. ‘When Miller and others ran the experiment with this chemically neutral mix, they only produced traces of glycine, the simplest amino acid.’ 6

The ‘Double Origin’ Theory

The ‘double origin’ theory for the emergence of life, as formulated by Freeman Dyson, suggests that the first lifeforms were protein-like molecules, which gradually evolved more sophisticated metabolisms, passing on their abilities to other proteins using enzymes as a primitive form of genetics. Later, more sophisticated genetic molecules like DNA emerged that were able to reproduce their traits much more accurately, but still lacked sophisticated metabolisms. However, eventually the proteins and the genetic molecules fused in a symbiotic relationship that produced life forms with a sophisticated metabolism and genetics. However, Dyson admits ‘that his ‘double origin’ theory is a highly speculative one, but scientists concede that today’s cells do show combinations of simpler life-forms’. 7 Thus, the paragraph on the ‘Primordial Soup’ concluded that ‘while teh primordial soup expected on the early Earth can create some of the most basic building blocks for life, it seems incapable of generating the crucial self-replicating molecules like DNA.’ 8

The RNA World

Most of the other theories discussed also had serious flaws. The RNA world, proposed in the 1980s, after it was discovered that RNA could act as catalyst and not just a carrier of genetic information, considers that the earliest life forms were naked genes of RNA. However, the article noted that while RNA can be persuaded to evolve new abilities, such as limited self-replication and the ability to link amino acids together, it so far has not demonstrated itself able to replicate itself completely as required for life on Earth. 9

Life from Clay

Graham Cairns-Smith’s own theory was that life was originally based on chemicals more robust than DNA, such as the clay mineral, kaolite. In this view, the first genes were defects in the crystal structure of these clays that were passed on to successive generations of crystals as they formed. However, there is no experimental evidence, according to the article, that clays really can replicate in this way. 10

Interestingly, the brief interview with Cairns-Smith suggests that the distinction drawn by some opponents of Intelligent Design between the origin of life and Darwinism is not accepted by all scientists. While Darwin himself did not discuss the origin of life, but merely speculated in a letter to a friend in 1871 that it may have occurred ‘in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity present’, Cairns-Smith himself stated that the process involved Natural Selection. 11 In answer to the question ‘What is your advice to anyone thinking of entering this area of research?’, Cairns-Smith answered ‘Oh, to forget about the chemistry of life as it is now and look creatively for the simplest real chemical systems that can evolve through natural selection, whatever they are made of.’ 12 It thus appears from Cairns-Smiths comments that however different the process of the origin of life may be from the evolution of living organisms, it is still held to be the product of Natural Selection.

The PNA World

The PNA theory arose from the work of Peter Nielsen of the University of Copenhagen in 1991. Nielsen used computers to design a molecule – Peptide Nucleic Acid, or PNA – that had the both the structure of DNA and the chemical abilities of proteins. He was intending to use it for cancer therapy, but its combination of the genetic quality of DNA and the resilience of proteins appealed to scientists struggling to discover the compounds that would have been suitable for the origin of life on Earth. PNA does share with DNA some limited capability for self-replication, but nothing on the scale of DNA. 13

Hydrothermal Vents

Regarding the origin of life around hydrothermal vents, while these do have iron sulphide, which performs a key process in living organisms by linking up amino acids, the extreme heat inside the vents, which exceeds 300 degrees Celsius, rapidly tears apart amino acids and DNA. Nevertheless, William Martin and his colleagues at the University of Dusseldorf in 2003 suggested that key reactions may still occur in cavities inside iron sulphide cells in the vents. 14

Panspermia

The paragraph on panspermia – the theory that life was seeded on Earth by comets and meteors from elsewhere in the cosmos –  noted that it was first proposed by Victorian scientists, and that its supporters included Francis Crick and Fred Hoyle. Its propnents argued that the discovery of amino acides in meteorites and bacteria high up in the Earth’s atmosphere support the theory. However, although this solved the problem of the origin of life on Earth, it was considered to be a ‘cop-out’ by many scientists because it pushed the problem away into deep space. 15

Creationism

As for Creationism, the article merely stated that it was ‘the oldest theory for the origin of life – and the simplest to explain: God did it.’ 16

Conclusion: Materialist Solutions of the Origin of Life Problematic

Thus, while the article certainly wasn’t as pessimistic about the possibility of discovering a materialist solution to the origin of life, it was clear that all the scientific theories presented had major flaws. The mention of Creationism alongside the materialist scientific theories is interesting. It’s clear that the article wasn’t written from a Creationist standpoint, and broadly supported the search for a materialist solution to the problem of the origin of life. Nevertheless, it seems extremely unlikely to me that many science magazines would ever have even mentioned Creationism as a solution at the time, even if merely for the sake of completeness, because of the threat that it is held to present to materialist science, which is construed and presented as genuine science in opposition to non-materialist approaches. It might have been because Creationism has, until very recently, been very much a minority point of view in Britain, though one that has been vigorously attacked over the past decades by Richard Dawkins, amongst others. With the growth of interest in Intelligent Design since the 1980s, I do wonder if Creationism would now be mentioned without an explicit condemnation, even in passing, in a British popular science magazine.

Notes

1. Robert Matthews, ‘History of Pondering Life’s Origins’, Focus, no. 130, September 2003, p. 39.

2. Matthews, ‘A Landmark Experiment’, Focus, no. 130, September 2003, pp. 38-41.

3. Matthews, ‘A Landmark Experiment’, Focus, no. 130, September 2003, p. 41.

4. Matthews, ‘A Landmark Experiment’, Focus, no. 130, September 2003, p. 40.

5. Matthews, ‘A Landmark Experiment’, Focus, no. 130, September 2003, pp. 40-41.

6. Matthews, ‘A Landmark Experiment’, Focus, no. 130, September 2003, p. 41.

7. Matthews, ‘Has Life Originated More than Once on Earth?’, Focus, no. 130, September 2003, p. 41.

8. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 42.

9. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 42.

10. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 42.

11. Matthews, ‘Meet the Origin of Life Expert’, Focus, no. 130, September 2003, p. 41.

12. Matthews, ‘Meet the Origin of Life Expert’, Focus, no. 130, September 2003, p. 41.

13. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 42.

14. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 43.

15. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 43.

16. Matthews, ‘How Did Life Get Started – Seven of the Most Popular Theories Currently being Debated’, Focus, no. 130, September 2003, p. 43.