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Infinite damage?
Aubrey Meyer of the Global Commons Institute correctly points out problems with the calculations of the value of human life carried out by David Pearce for the working group of the Intergovernmental Panel on Climate Change (Letters, 30 September). The calculations were carried out on the basis of a willingness to pay (WTP) rather than a willingness to accept (WTA). Consequently, damage to societies with few financial resources is undervalued and the analysis is biased in favour of rich polluters and against poor victims.
Unfortunately, a WTA analysis can also lead to absurdities. This can be illustrated by what has happened to mines in Papua New Guinea. The Ok Tedi gold mine, for example, has recently been in the spotlight in Australia because of compensation demands from a small number of hunters and subsistence agriculturalists whose lives and environment have been completely disrupted by the tailings from the multi-billion dollar mine. The mine has already paid out vastly more in compensation, shares, and provision of services than the local people would have otherwise seen in their lives. But some of the people remain unhappy with what has happened, and will remain unhappy however much the mine pays out. They cannot be criticised for this, since they did not ask for the mine to be set up and nor could they possibly have imagined what would happen.
Meanwhile the mining company continues to extract gold as rapidly as possible, provided this maximises its rate of return, and will pay whatever compensation and legal fees it needs to in order to continue operating profitably.
In this situation, which has many analogies, a WTP analysis would have ignored the disruption to a small number of people outside the cash economy. In contrast, rigorous WTA analysis values the damage at infinity and implies that any individual whose life is disrupted has the right to close down the mine.
The interests of Papua New Guinea would clearly be better served by more restrained minerals development, minimising environmental disruption and providing revenue in a manner in which it can be absorbed usefully by the local economy. This is not what is achieved at present, when mining companies aim to maximise their rate of return whilst paying whatever compensation they need in order to keep going.
What should be apparent to readers of New 杏吧原创 is that no method for valuing human life provides an objective or “scientific” rationale for making decisions which are essentially political. Cost-benefit analyses provide a means of disguising one’s political prejudices with pseudoscience. And WTA analyses, as well as WTP ones, promote the false impression that politics is no more than an exercise in accountancy.
TB and class
The report by Abi Berger on the conference on tuberculosis overlooked the dissenting opinions which arose from the floor of that overmanaged conference (This Week, 23 September).
The great preponderance of presenters and attenders agreed that the rates of TB incidence and mortality depend heavily on poverty, overcrowding, nutrition, instability of populations, and other environmental and socioeconomic factors. However, the organising committee had an agenda to push, namely getting funding for the biomedical model of control – chemotherapy now and a possible vaccine in the vague future.
Dissenters pointed out that this model has never been proven as a long-term control pathway, whereas improvements in living and working conditions and in social mobility and community stability have been the acknowledged cause of the decline in TB incidence and mortality since the 19th century, long before the anti-TB drugs.
The New York Directly Observed Therapy programme has not yet proved to be the answer. As long as the public policy of three levels of government (municipal, state, and federal) targets poor minority areas for destabilisation, housing destruction, and shortchanging of vital services such as fire control and garbage collection, TB will arise in the targeted zones.
All three levels of government let the disease go into epidemic and rage through the poor neighbourhoods until saturation was reached with spillover into the middleclass neighbourhoods. Suburban commuters began coming down with infections and active disease. As soon as the middle class felt the epidemic, then something had to be done.
Rather than attacking the problem in a balanced way aimed at achieving long-term solutions, the government agencies and the academics who receive government funding decided to depend entirely on drug treatment. This method leads the middle class to believe that it is being protected, yet allows the governments to continue targeting the poor with punitive and discriminatory public policies. This dependence on drugs also raises the probability of an outbreak of multiple drug-resistant TB.
Grasping the nettle
Gabrielle Hatfield suggests that the book The Art of Farriery is wrong and that the story she was told by a modern stallion owner 鈥� that nettles are used to beat a mare after being visited by the stallion 鈥� is correct (Forum, 14 October).
In my experience, both are wrong unless the author is trying to be polite in her description of the method of “beating” the mare, or the stallion owner was too shy to be specific.
When I first started owning horses some thirty years ago I was fortunate enough to have a gypsy horseman assist me in extending my knowledge of how to deal with horses as well as how to handle them.
When it came to the stallion time, he introduced the stallion to the mare and immediately afterwards put a bunch of nettles where the stallion had been. His explanation for this is that the stinging does not harm the mare but ensures that she sucks the stallion’s semen up into her instead of making water and washing it out as is often the case.
This seemed to me at the time a good reason to do this and the mare produced a foal on the expected date without the need for the stallion to come again.
Case unproved
Your readers raise a number of questions about possible health risks associated with exposure to electromagnetic fields (EMFs) (Letters, 28 October). There are some points I should like to make in response.
In recent years the main focus of concern has been on domestic and occupational exposure to power frequency electromagnetic fields (50 hertz in Britain) and the possible association with childhood and adult cancer (This Week, 7 October).
Epidemiological and experimental studies covering possible risks to health from EMFs have been comprehensively reviewed by the British National Radiological Protection Board’s Advisory Group on Non-ionising Radiation, chaired by Sir Richard Doll. It is clear that EMFs have insufficient energy to damage the DNA in cells directly. Therefore they cannot initiate cancer in the way that ionising radiations, such as X- and gamma rays, do.
The only possibility seems to be that they may encourage cancer to develop. A number of epidemiological studies provide some evidence of an association between exposure to EMFs and childhood leukaemia. The number of affected children in the studies is, however, very small. The advisory group has concluded that, at the normal levels of exposure, there is no persuasive biological evidence that EMFs can influence any of the accepted stages in carcinogenesis. Neither is there a clear basis on which to develop a meaningful assessment of risk, nor any indication of how any risk might vary with exposure.
The NRPB has therefore taken the view that although some of these epidemiological studies may suggest an association between EMFs and cancer, this must be clearly distinguished from causation. The NRPB issued guidelines on limiting exposure to EMFs and radiation in 1993 which took into account the views of the advisory group. The guidelines are based solely on preventing the well-established biological effects of electromagnetic fields and radiation, which at power frequencies include effects on electrically excitable cells.
In common with other national and international bodies concerned with EMFs and health, the NRPB considers that it is not possible to use the published data from epidemiological studies as a sound basis for the formulation of restrictions on EMF exposure.
Although cancer has been the main cause for concern, a few fragmentary papers have been published that have suggested associations with other diseases such as Alzheimer’s and adverse effects on the nervous system and mental function. These studies have not yet been backed up by further research and can only be seen as providing hypotheses.
This lack of evidence for harmful effects of EMFs contrasts with the information on ionising radiation, where a range of epidemiological studies have unequivocally demonstrated a cancer risk. There is also very strong supporting evidence from studies with experimental animals, while cellular and molecular studies have demonstrated direct effects of ionising radiation on DNA and are now serving to elucidate the mechanisms involved in carcinogenesis.
Habitat hotspots
Stephen Budiansky claims that the balance of nature is an outdated notion and that ecologists will not be able to tackle real problems until they admit it (“Chaos in Eden”, 14 October). But it is hard to relate this claim to the article 鈥� an amalgam of straw men and quotations which are as misleading and dangerous as those Budiansky accuses ecologists of indulging in, especially with regard to extinctions.
The extinction rates quoted by Budiansky originate from a 1994 paper in Nature (vol 364, p 494). This paper described the underlying assumptions of the analysis, and it is depressing that the rates were quoted in a strap in the article, with no qualification at all. The assumptions are that we know all the extinctions which have occurred globally since 1600, and that any species observed even once since 1945 cannot be listed as extinct, simply by definition. Few field ecologists would deny that though relatively few species may be technically extinct to date, the waiting list of “living dead” queuing to join is ominously long, and growing.
I would argue that the conclusions drawn from present knowledge of rates of habitat loss and extinction probability are relatively clear, fairly well agreed by ecologists, and can be summarised as follows:
As a first rule in a fuzzy, multivariate world, a real loss of a habitat leads to a nonlinear loss of species over a long time frame. A species lost through destruction of a habitat will only be recorded as a global extinction if it is found nowhere else in the world, although its loss from a particular region may have significant economic and aesthetic impacts.
A positive interpretation of the species-area rule which Budiansky criticises would be that, if 99 per cent loss of a habitat may lead to an eventual loss of around three-quarters of all species from that area, conservation of 10 per cent of a habitat area might reduce this loss to less than half.
Sadly, even achieving a natural habitat protection goal of 5 per cent is a major challenge for ecologists over the next decade. However, judicious selection of conservation habitat on the basis of global, regional and local species endemism hotspots, coupled with sensible habitat management by intervention, could reduce overall costs and improve the efficiency of biodiversity conservation. Last-minute scrambles to rescue endangered species in small natural habitat patches, such as Golden Lion tamarins in Brazilian Atlantic rainforest fragments, are both more expensive and risky, although strangely, they are easier to promote in political terms.
Budiansky is simply wrong when he states that failure to recognise that the concept of the balance of nature is outdated is preventing ecologists from tackling real problems. It is more a failure to realise that, in an increasingly crowded world, decisions on land use are dominated more by political than straightforward scientific argument. Honest scientific debate can be a two-edged sword in a world driven by politics and the media.
Budiansky is right to question models and simplistic theories which are no longer tenable.
It does not follow from this that there is no such thing as a “plant community”, nor that man’s intervention cannot be harmful. The association between an oak tree and Phellinus robustus (In Brief, 14 October) is why the British Mycological Society wished to preserve the tree. Cypripedium orchids require “servicing” (pollination) by bees of just the right type and their seedlings form mycorrhizal unions with certain fungi, without which they perish.
Low extinction rates today may reflect increasing interest and improving techniques in conservation. The good news about “extinct” Brazilian butterflies might just mean that today’s surveys are more efficient than they once were.
If numbers (or habitats) of a given species are drastically reduced, then extinction may follow in its own time as a result of one of the “chance disturbances” (like fire) which Budiansky quotes.
Budiansky seems to rubbish the idea of “climax”. However, take any map of the world and you can state the overall climatic climax of that part of the world (for example, Arctic tundra, tropical rainforest).
Ecologists have long recognised different types of climax 鈥� climatic, edaphic and biotic. It cannot be disputed that the climatic climax over most of England would be broad-leaved woodland, with, for example, the edaphic climax of raised bogs in certain areas.
The climax state itself can be dynamic with, for example, tree composition varying over time, and climaxes themselves relate only to the prevailing conditions 鈥� continental drift and climate change, for example, both result in changes to the climax community of a given region. You can also overplay the role of disasters 鈥� ecosystems do tend to follow a successional route back to a climax after disasters.
Ancient turds
Nature has a letter on 28 September stating that “a few remarkable finds document the colonisation of land by animals and plants in the mid-Palaeozoic, but much rarer is unequivocal evidence for plant animal interaction. Here we announce the discovery of 鈥� fossil faeces 鈥� at 412 million years old in rocks that predate other examples 鈥� by about 90 million years.”
New 杏吧原创 deifies that letter under the headline “Possibly the oldest turds in the world”, saying that “there has to be a first for everything. In this week’s issue of Nature, British researchers proudly unveil the earliest known terrestrial faeces” (This Week, 30 September). Neither the message, the messenger nor the sender assert correctly.
The Proceedings of the National Academy of Science of September 1985 contains an article by my daughter and her colleagues, E.I. Robbins, K. Porter and K. Haberyan, which gives evidence for microfossil faecal pellets in the period between 2 and 2.5 gigayears ago. Are we to assume that the former is a 10th nonanniversary of the latter, or merely an overlooked reference? Their article also received its acknowledgement under the title “On the Origin of Faeces” in a journal devoted to such sharp commentary and wit.
Wonder of worms
I had barely started celebrating the news that nematodes are beginning to receive the attention they deserve (This Week, 16 September) when the reactionary comments of David Burnie (Letters, 14 October) deflated my delight.
His main gripe is that nematodes are morphologically conservative. To me, that a relatively simple body should be so adaptable is the wonder of nematodes. No other body plan has allowed so many habitats to be successfully colonised. No other body plan allows such a range of size (from the 0.3 millimetres of an adult Paratylenchus to the 8 metres of Placentonema gigantissima).
If the estimates of the number of nematode species are correct it may be that there will be a much greater diversity of form of nematodes awaiting discovery. As it is, it’s not true to say that “once you have seen one you have them all”, as Burnie claims. What insect can rival the bizarre Sphaerularia bombi in which the everted uterus of the female grows until it is 30 times the length and 300 times the volume of the remainder of her body?
The increasing value of nematodes to humans is also worth remembering. The nematode Caenorhabditis elegans was the first metazoan to have its genome intensively studied and many of the techniques used in the human genome project were developed using this species. Nematodes are increasingly valued as bioindicators. Other species are now available for the biological control of slugs and, even more gratifying, of insects.
Eat your tubular hearts out insects, nematodes don’t need one.