Two of my Facebook contacts have been involved in an animated discussion on the subject of food allergy. The thread considered several important points, but the passions it aroused in some of the participants raised some painful memories from my former life.
My study of archaeological theory has taught me a great deal; I do wish I had started earlier. One thing I have learned is that the position of objective, entirely neutral, observer is a myth. All of us see the world ‘not as it is, but as we are’. Even if we do everything within our power to separate our observations from our interpretations we always fail because of personal experiences we cannot ignore, or prejudices of which we are quite unaware. You will be sad to learn that the world of academic theoretical archaeology does not consist of benignly competing, though mutually supportive, schools of thought but is rather riven by bitter divisions and irreconcilable hostilities.
So, just like medicine then. I didn’t leave the NHS to study archaeology for any single cause, and love of the past (or correctly those portions of our past which survive into our present) was always an enormous draw. But I was immensely glad to leave certain conversations behind, conversations which tended to go like this:
Patient: (speaking) ‘you are arrogant and ignorant. Seeing you was a total waste of time, you don’t know what you are talking about’.
Me: (speaking) ‘try to look at this rationally……’ (while thinking) ‘I have degrees from Cambridge and London. I am a fellow of the Royal College of Physicians. My post-graduate training took seven years and I have over twenty years experience as a consultant physician. I have no reason not to give you the best advice I can, although everyone can make honest mistakes and you may disagree with my advice – as is your privilege. Since I work wholly within the NHS your visit, tests, and treatment have cost you nothing. So why are you cross with me?’
My old dermatology department at St Luke’s Hospital had special interests in the early diagnosis of skin cancer, a severe skin disease called psoriasis, and the treatment of imported infections like leprosy and cutaneous leishmaniasis. Important work. Conversations like the one I have reported never occurred with patients suffering from these conditions, although the matters we did discuss could certainly be painful and difficult. The topics that rather wore me down were presumed allergies and skin diseases of a psychological origin. I could never understand why these disorders should be more difficult to discuss quietly and rationally than any others, and my incapacity in this respect plausibly accounts for my record of failure.
To begin with I should say that by ‘allergy’ I don’t mean those allergies expressed on the skin itself, to perfume perhaps, or epoxy resin, or to the metal nickel. There are reliable confirmatory tests for these problems once you have undertaken some very interesting preliminary detective work. Nor do I mean life threatening allergic reactions to nuts, eggs, penicillin or insect stings. A patient’s history almost always clearly indicates those conditions, and in any case there are reliable confirmatory blood tests available. There was also a fascinating, extremely itchy, condition called dermatitis herpetiformis of which I have provided a picture; this is unquestionably linked to gluten sensitivity. No, the allergies that proved contentious were food allergies that were possibly linked with skin disorders such as atopic eczema and urticaria (nettle-rash).
In archaeology, before we decide if a site is Neolithic or Iron Age in date, we have to reach agreement about what those cultural terms mean. It’s the same in medicine. I would propose that if a plant product contains a substance that damages almost everybody who ingests it (like wine or certain mushrooms) then that is toxicity. If a plant which is normally harmless, or even beneficial, to consume causes serious adverse reactions in a small number of people, and these adverse reactions are mediated by the immune system, then that is allergy, sometimes called hypersensitivity. If a plant which is normally harmless, or beneficial, to consume causes serious adverse reactions in a small number of people, but these adverse reactions are not mediated by the immune system (they might for instance result from an abnormality of a key metabolising enzyme as is the case with the disease phenylketonuria) then that is intolerance.
Despite the evident difficulties, we have to try to distinguish between observations and interpretation. In archaeology if you find a hole in the ground with bones in it you have found a burial. Burial is an observation but to call the same find ‘an interment within a grave’ is providing an instant interpretation which may or may not be justified. Similarly if you develop extensive urticaria then that is an observation, and one that can hardly be challenged if you have a photographic record. But if, on the basis of your recent dietary history, you say ‘Aha, I am allergic to oranges’ that is an interpretation and one that can very definitely be challenged. I know whereof I speak. I had urticaria as a child and my wretched existence was made just that little bit more wretched by having all the foods I enjoyed: oranges, chocolate, pork-pies, withdrawn one after another. All quite pointless; most patients with the common chronic versions of this condition do not appear to have a food allergy, although aspirin does predictably worsen the condition.
In both archaeology and medicine there can also be a problem with unavailable evidence. For example: you date a site by means of a Roman coin find. You send the coin to an expert but it is mysteriously lost before a report is written. You know what you saw but you must understand that it will be very difficult to convince others because the crucial evidence is now missing and cannot be observed again. Imagine that your life is being made wretched by severe headaches. There can be no objective evidence for the existence or severity of this symptom since it is something which you experience internally. You know what the headache feels like but if no cause is discovered can you accept that others may wonder if the symptoms represent a miss-perception on your part?
So where did my problems originate and why did I get into trouble? Patients with the hypothetical Hobbit’s disease ‘know’ from their own experience that the cause is wheat allergy combined with long quests. They put themselves on a gluten free diet and feel better as a result. That’s absolutely fine of course; who am I to say that they don’t experience an improvement? If, for one reason or another, they want a medical diagnosis of gluten sensitivity then there are blood tests and intestinal biopsies available to confirm this. If those tests are not undertaken, or the results are negative, then I would likely have concluded that the perceived beneficial benefits of the diet are an example of the ‘placebo effect’ or alternatively I might use that valuable Scottish verdict ‘unproven’. This is not a criticism of anybody’s character just an inevitable clinical deduction. I reacted in the same way when I met a lady who said she could ‘feel’ the presence of Romans in the landscape. I wouldn’t ask any adult to change their dietary behaviour as a result of my disbelief, although in the case of a child I might well feel happier to have a professional dietitian’s reassurance that no essential vitamins or nutrients are likely to be missed out as a consequence.
An additional complication used to arise when the patient was accompanied by a private lab report indicating that they were allergic to one or more, often many more, food items. Sometimes these tests were undertaken on hair samples which I am fairly certain is a simple fraud. Sometimes blood levels of a protein known as immunoglobulin E had been estimated. Under certain circumstances this test can be invaluable. Someone who has had a severe, life-threatening reaction to a flying insect sting may only recall that the culprit was yellow and black. Looking at blood IgE directed against bee and wasp venom provides a highly valuable species identification. Unfortunately sufferers from atopy (asthma, hay-fever or atopic eczema) invariably have multiple raised IgE levels directed against many foodstuffs and other common environmental proteins (grass pollen, house dust mite, milk protein, cat fur, horse dander, egg albumin etc). Deciding whether all, or any, of these are actually ‘clinically significant’ is a most challenging problem. I must have supervised dozens of people on house dust mite avoidance schemes, or restriction diets of various types, for the management of their eczema; some did feel they were mildly to moderately improved but I must say I never witnessed a life-changing results. Possibly my heart wasn’t in it, but please never say ‘lamb and pear diet’ to me unless you want to see a strong man cry.
I’ll try to reach a conclusion: in both archaeology and medicine it is alway important to think about the quality of the evidence. A large study, peer reviewed, and published in Antiquity or Nature is not an absolute guarantee of quality but such studies must be taken very seriously indeed. A paper published on the same subject by an ‘in-house’ journal of an organisation with a financial interest in a particular outcome is generally of less significance. Whatever the evidence you have remember not to go too far beyond it. Imagine that you find a Saxon site in Kent, fine. Saying that ‘Kent was conquered by the Saxons’ as a result of your findings goes way beyond the available facts. In medicine describing a reasonable biochemical justification for a treatment, or a diet, is one thing, but demonstrating worthwhile benefits, in statistically significant groups of patients in a clinical setting, is something else entirely.
Relatively recently, say somewhat less than seven thousand years ago in the UK, Mesolithic hunter-gatherer-fisher societies switched to a Neolithic diet based largely on farmed wheat and milk products. Why they did this is still far from clear but it was a huge change and one that human metabolism may well still be adjusting to. It is improbable that human evolution has successfully prepared us for large quantities of cane sugar, Virginia cigarettes or Carling Special Brew. Years of research have demonstrated that ingested items like tobacco, alcohol, and betel are associated with specific human cancers. This is not at all the same thing as saying ‘cancer is caused by food’. A causal link has to be demonstrated for each food and for each cancer, and this is a mighty difficult trick to bring off. Correlation does not necessarily imply causation. I think that we all have to accept that in the field of food allergy, as well as in archaeology, two people can examine the same observations but reach totally different conclusions. If you find yourself in this situation I would urge you not to be so committed to your own personal interpretation that you consider anyone who diverges from it to be foolish, arrogant or hostile. I have come to conclude that some people become so wedded to an archaeological hypothesis, or a diagnosis they believe that they have, that it becomes integrated into their personality. To attack the hypothesis, or the diagnosis, is perceived as an attack on them.
So, how do I finish? Firstly a piece of advice from my late father: ‘don’t shoot the pianist he’s doing his best’. Secondly something that a most charismatic doctor called Richard Asher penned fifty years ago as advice for people who want the best chance of having a long life: ‘don’t smoke, or drink alcohol. Don’t eat too much, get plenty of exercise, and choose your parents carefully’. How true. Now you can start shouting at me, if it makes you feel better, but remember that no doctor is put into this world simply to fulfill your expectations.