Oxygen: the Molecule that made the World

The word ‘enthusiast’ has changed in meaning over the years. In the eighteenth century, it was not wholly complimentary: ‘One who vainly imagines a private revelation; one of a hot imagination or violent passions; one of elevated fancy or exalted ideas’ wrote Dr Johnson in his Dictionary of 1755. Addison noted with distaste that certain religious sects displayed ‘strong Tinctures of Enthusiasm’. Nick Lane is clearly an enthusiast in a modern, non-pejorative sense. What other description can you apply to an author who sets out to write about ‘... life, death and oxygen: about how and why life produced and adapted to oxygen; about the evolutionary past and future of life on Earth; about energy and health, disease and death, sex and regeneration; and about ourselves’ (p. 2)? All this in a book¹ that is ‘... not a catalogue of dry facts... rather, like science itself, it is full of quirks, experiments, oddities, speculations, hypotheses and predictions’ (pp. 13-14). These two quotations are useful in that they at once indicate the ambitious scale of the book and some of the difficulties the reader may encounter.

Paraphrasing and grossly reducing Lane's own aims, we may say that he pursues three huge topics—the formation of an oxygenated atmosphere, the emergence of oxygen-dependent organisms, and the complementary hazards of oxygen toxicity. About one-third of the way through the book, chapter five, readers may be disconcerted to find themselves no further than the carboniferous period; but by chapter fifteen they will have found extended discussions of the biochemical, biological and pathological aspects of free radicals. Much emphasis is given to ageing and to age-related diseases.

Lane necessarily draws on information from a wide range of disciplines: a list including geology, geochemistry, palaeontology, biochemistry, zoology, genetics, molecular biology and medicine is representative but by no means complete. In any one of them, experimentally described data will (self-evidently) vary enormously in terms of the methodologies by which they are derived and the extent to which they can be validated and legitimately extrapolated. Certain findings, sometimes obtained from restricted and highly contrived conditions, may prove to be compatible with other observations and come to form an evidential basis for plausible, testable theories. Cumulative weight of evidence is a familiar notion; but so, too, is the recognition of anomalies which (though securely based) do not fit into accepted schemata and may indeed eventually lead to their modification or rejection. This state of permanently unfinished business is difficult to convey in accurate and general terms for any one branch of scientific activity; and for Lane to undertake similar tasks in so many and disparate fields is a formidable challenge.

He compounds his difficulties by including much speculative material. Lane clearly enjoys the counter-intuitive and the iconoclastic, but the reader must be given a sufficiently detailed conventional context in which the more controversial observations can be adequately appraised—particularly the general reader to whom this book is directed. The scope and diversity of the subject matter makes this requirement almost impossible to achieve with uniform success. Lane also has a disconcerting tendency to argue from overtly weak grounds (‘... evidence is not compelling, but is certainly intriguing’ [p. 139]) and, even more surprisingly, he sometimes reinstates the intuitive interpretations and responses which he has previously disparaged. Thus ‘A more subtle version of the mitochondrial theory [of ageing] must be true’— (p. 266). Or ‘Set against the potential dead end of experimental research is the intuitive explanatory power of free radicals as a cause of ageing and disease. The fact is that free radicals are detected in virtually every disease known to man, and that in principle they can explain the progression of ageing and the rising incidence of age-related diseases’ (p. 318).

These are generalities, and the identification of more specific points of reservations and disagreement in the text will depend on the particular interests and expertise of the individual reader. Various statements that are questionable, perverse or just wrong will be picked up by medical readers. Thus, how well founded is the statement that ‘People who reach the age of 100 in good health often have a similar accumulation of damage to their DNA, lipids and proteins as people in poor health at the age of 50’ (p. 292)? Or the conclusion that ‘... for most people with Alzheimer's disease, oxidative stress is the earliest pathological change...’ (p. 305); or, on the same topic, that ‘One antioxidant proved to delay the onset of Alzheimer's disease is vitamin E’ (p. 306)? What can you make of the statement that ‘... people with Down syndrome have an additional copy of chromosome 23... researchers have noted that the gene for SOD [superoxide dismutase] sits on chromosome 23. People with Down syndrome therefore make too much SOD. The syndrome itself is characterized by oxidative stress, leading to neurological degeneration. It may be that people with Down syndrome suffer oxidative stress because they have too much SOD’ (p. 202). Down syndrome is later correctly associated with chromosome 21 (p. 304) but the alleged role of oxidative stress here and in many other conditions (‘There are hundreds of diseases in which [it] is known to play a role’ [p. 313]) is difficult to square with Lane's own quotations of severe criticisms of the theory. Ames and his colleagues concluded in 1999 that ‘... the range of estimates of oxidative damage spans more than 60,000 fold’ (p. 264). Shift attention to cancer and you read that ‘The frequent mutations in cancer cells are usually considered to be the cause of cancer, but... it is not known whether such mutations occur first, and then stimulate cancer cells to proliferate, or whether the mutations accumulate in cancer cells that are already proliferating’ (p. 312). Or ‘Cigarette smoke is dangerous because it is the most dastardly free-radical generator known.... Smoking thus provokes inflammation and this is the chief reason for the high risk of both heart disease and cancer’ (pp. 310, 311). Or ‘The so-called Balkan War syndrome (a form of leukaemia)...’ (p. 111).

Two quotations were cited at the beginning of this review in which Lane sets out the aims of his book and the approaches he adopted in writing it. A third quotation may serve as a conclusion:

‘As medical research grows ever more specialized, it becomes at once less acceptable and more necessary to transgress the limits of personal expertise. Perhaps this is the most valuable role of the science writer: writers must transgress their own expertise as a matter of routine, and flights of fancy can at least be brought down to earth by experts’ (p. 294).