Evolutionary insights for public policy

The significance of an evolutionary approach to public health is increasingly being recognised. The negative effects of poverty and inequality are also being recognised as a huge burden on health. Occasionally, the two are even combined to acknowledge our evolved responses to inequality.

Overall though the various efforts seem to have stopped short of explicitly proposing an evolutionary explanation to the Spirit Level evidence between countries. Understandably, the focus has been on measures like teenage pregnancy and breastfeeding rates that directly measure life history (LH) strategy (see this post on LH theory). But other outcomes may be the result of a faster LH strategy too: infant mortality may be higher in more unequal countries because of a reduced biological investment in each child, leading to low birthweight and prematurity.

The other outcomes in the Spirit Level can be brought under the life history strategy umbrella too, with its general principle of short-termism. The harsher and more unequal the social environment, the more uncertainty there is over long-term prospects. This would have been true in our ancestral environment too, and with morbidity and mortality rates so much higher, the selection pressure on behavioural strategies would have been extremely strong. The danger of dying before or during reproductive years made early reproduction paramount. As a result, we evolved a comprehensive response to harshness, which speeds up the course and development of key life stages, and prioritises reproduction over growth.

The response is evident in various domains:

Biologically, periods of growth are shortened, and puberty is brought forward. As in Barker’s thrifty phenotype hypothesis, where less important organs like the pancreas get less energetic investment when energy is scarce, physical size is sacrificed to allow reproduction to occur earlier. This under-investment early on in life may lead to the various health problems that develop later. Of course middle-aged health problems wouldn’t have been a major problem evolutionarily, if the early reproduction meant that your genes had been passed on in a difficult environment. They may not even have developed, with an environment of low calorie availability and an active lifestyle avoiding the metabolic disorders seen today. The molecular symptom of quicker development is oxidative stress, which is a measure of the biological stress on an individual. It is linked with chronic low-level inflammation and suppression of the immune system. Heightened cortisol levels, and activation of the hypothalamic-pituitary-adrenal axis which releases adrenaline, are also implicated. The response to stress is complex, but the various measures are consistently related to low socioeconomic status, and so can be argued to be part of the fast LH strategy.

Cognitively, people show a higher rate of a cognitive bias known as future discounting. This involves taking smaller, short-term gains at the expense of larger, long-term ones. Delaying gratification and impulse control require a low rate of future discounting.

Behaviourally, this bias could be argued to underlie almost any of the behavioural problems in the Spirit Level – drop-out rates from high school and low educational attainment, unsustainable environmental practices, addiction of any kind, from gambling to alcohol and drugs. Public goods problems (like climate change) require a long-term assessment of costs and benefits, so a bias to discount the future is disastrous for agreements on action. Hierarchy also encourages conspicuous consumption to signal status – another unsustainable practice. Future discounting may explain why trust is lower in more unequal countries, as a long-term view is needed to help someone today, when you may not be paid back for a while.

Parental investment is another feature which is sacrificed in the fast LH strategy. This is seen in harsher parenting styles. Parental inconsistency has been linked with elevated levels of stress hormones in children. And one of the parents may not even be there – 26% of families in 2011 were single-parent households. Absent fathers account for the vast majority of these. The effect on boys is the development of excessively masculine traits; girls hit puberty earlier. Both genders are more likely than average to repeat their parent’s lifestyle. The UNICEF index of child wellbeing correlates negatively with inequality, as do childhood behavioural problems.

Consequently, mental health suffers in unequal societies – especially anxiety. This can’t be said to be adaptive in modern society, but as with chronic stress, it is possible to theorise how it could have helped in an ancestral environment. In small doses, anxiety and low mood may have been one way of avoiding conflict, by avoiding aggression from others. But as with stress, constant exposure is pathological.

Inequality, by stratifying the social hierarchy, favours competition over cooperation as the way we interact with each other. Status becomes more important, as it has always signalled an ability to access resources, including mates. Excessive inequality means that those at the top can monopolise resources, and those at the bottom have nothing to lose when they try to climb the ladder. This manifests itself in higher rates of violence and homicide. Men may go to greater lengths to keep partners as well as compete for them, using violence and sexual coercion. The violence statistics don’t include sexual violence due to international differences in definitions, but (not unrelatedly) the status of women and gender equality are better in more equal countries.

In order to bring about the policy changes necessary to reduce inequality, disparate interest groups need to be made aware of the wide-ranging effects of inequality and the associated LH traits, in order to campaign with a louder voice together. This means physical and mental health organisations, alcohol and drugs charities, violence reduction schemes and so on could benefit from coming together to work for something that would tackle all of their respective issues at source. It’s not about creating a ‘natural’ environment – there’s no such thing, as we adapt to vastly different societies. It’s recognising that a more equal society brings out the best of our nature.

Climate and the Glasgow Effect

Rain at Glasgow Necropolis

Rain at Glasgow Necropolis (Photo credit: Wikipedia)

54 years is the male life expectancy in the Republic of the Congo, Papua New Guinea, and the Calton area of Glasgow. The excess mortality in Glasgow and West Central Scotland in general which leads to such stark statistics has been dubbed the Glasgow Effect. Excess is the key word though – these are deaths, especially early deaths, which cannot be explained by the usual culprit of socioeconomic deprivation. As such, the Glasgow Effect is a much smaller problem than the nationwide health inequalities that result from inequality and deprivation. But because there is no obvious explanation for it, numerous researchers in Glasgow are on the case.

A Tale of Three Cities

It was the best of times, it was the worst of times – Glasgow in the 1970s had comparatively low excess mortality to other cities, but was suffering the collapse of heavy industry, and the beginnings of neoliberal economic policy. Since then, the ‘mortality gap’ has grown. Comparable cities haven’t suffered the same unhealthy fate though –  Liverpool and Manchester have almost identical levels of deprivation, and had similar levels of heavy industry and aversion to Thatcherism, but when the three cities are compared, Glasgow has 15% more deaths, and 30% more deaths under the age of 65. Any potential explanation of the Glasgow Effect must therefore rely on a set of factors which are systematically different in Glasgow.

This is where a lot of potential explanations fall down, as a lot of them are closely linked to the deprivation profile, which doesn’t vary between the cities. Immediate causes of ill health like smoking being more prevalent in Glasgow don’t offer a satisfying explanation either, as they simply shift the causation question back, to ask why smoking is more prevalent in Glasgow. A full explanation must include factors which could feasibly contribute to worse health behaviours in the first place.

Why does it always rain on me?

One unlikely candidate is the weather (well it would explain why the British are obsessed with it). Scotland, particularly the West, is one of the wettest places in Europe. Glasgow’s reputation as being wetter than other cities is borne out by the climatic data – Abbotsinch gets 1080mm per year, with Paisley getting 1200mm, compared to 700mm falling on Edinburgh. Liverpool averages 700-850mm per year, with Manchester getting 800mm. The additional rainfall means that Glasgow gets fewer hours of sunshine too. An increase in Glasgow’s rainfall since 1971 even correlates with the emergence of the Glasgow effect.

Sunshine on Leith

But correlation doesn’t equal causation. How does the climate affect health? One theory on the link is being researched in Glasgow. It focuses on sunshine, which the skin uses to synthesise vitamin D. As well as rickets, low levels of vitamin D have been linked with chronic disease and mortality. We can’t get enough from our diet (oily fish and eggs are good though), and if the climate isn’t conducive to sunbathing, this may contribute to the majority of the population being vitamin D deficient. As well as getting less sunshine, the greater cloud cover in the West of Scotland means that less UV light makes it through, which may make things worse (true to form, despite lower UV levels, Scotland manages to have higher than the UK average of skin cancer rates). To link vitamin D deficiency to the Glasgow Effect, a link with premature mortality would need to be established. This is the aim of a current research project at the Glasgow Centre for Population Health.

An element of the link between vitamin D and health may be due to low levels being a marker of other risk factors, like obesity and inactivity. These factors shift the mechanism from being purely physical to involving behavioural factors too. But these behavioural factors could also be being influenced by the weather. This is straying from established theories, but existing evidence can be applied to the context of the Glasgow Effect.

Glasgow Smiles Better?

Seasonal Affective Disorder (SAD) is a prime example of how the environment can affect our health. In the winter months, susceptible individuals get depressed due to the lack of natural light available. Naturally, the further north you live, the more likely you are to develop SAD, but this correlation is surprisingly weak. Stronger links have been shown to exist between climatic variables like hours of sunshine and cloudiness. If this applies in Glasgow, a higher incidence of SAD would be expected. As well as the toll on mental health, higher levels of SAD would explain some of the worse physical health – SAD is associated with weight gain and inactivity. The bulk of Glasgow’s extra rainfall comes from autumn to spring – in the winter it gets around twice as much precipitation than Liverpool and Manchester. It looks like a perfect storm for SAD.

The neurotransmitter serotonin is thought to underlie the mechanism by which SAD progresses. Associated with mood and wellbeing, serotonin is transported away from the brain more in winter. This process is decreased the more hours of sunshine there are, and increased the more humid it is.

Under the weather

Other neurotransmitters may equally play a role in the climate’s effect on health. Endorphins are released by, amongst other things, prolonged exercise and exposure to sunlight. Glasgow’s excess rainfall and sunshine deficit hardly encourage exercise. An endorphin deficit has a number of negative effects on health. Endorphins along with oxytocin act as an appetite suppressant, especially against salty food. There is evidence that endorphins have a direct effect on the immune system – beta-endorphin has been shown to produce natural killer cells, which kill cancer cells and slow the ageing process. In addition, if Glaswegians did have lower levels of endorphins, they’d be missing out on the pain relief and feeling of wellbeing they provide.

There are other ways of releasing endorphins, but they aren’t nearly as healthy. Eating sweet, carbohydrate-rich food like chocolate is one of them. A more drastic measure is to take artificial opiates, which include drugs like heroin and methadone. Drug abuse is heavily involved in the premature deaths which contribute to the Glasgow Effect. It’s also feasible that comfort eating (and drinking) increase when the weather is bad. It’s fairly speculative to link climate to drug abuse, but the theory, like the others above, is testable – do Glaswegians have lower levels of vitamin D/serotonin/endorphins?


So is living in Glasgow harmful to health? To the extent that the weather is to blame, there are ways of minimising its impact. Some common sense tips would be to make the most of the sun when it’s out (without getting sunburnt), and to keep active and outdoors especially during the winter – Glasgow has (or at least used to have) more parkland per head of population than any other city in Europe, so there’s no excuse not to. Going on holiday during the winter makes a lot of sense too.

It would be fascinating if a link were to be discovered between Glasgow’s climate and the Glasgow Effect, but this would still only concern the excess mortality compared to Liverpool and Manchester. Even if the Glasgow Effect was eradicated, Glasgow would remain one of the unhealthiest cities in the UK. This much bigger health deficit compared to other parts of the country is attributable to deprivation and inequality, which must be reduced if Glasgow’s health is to improve.

May Contain Artificial Colours

Walking down the aisle – Image by Sean MacEntee via Flickr

Nutritional information on the front of food packaging can be presented in one of two ways: using the traffic light system, or as guideline daily allowances (GDAs), which display the amount of a nutrient in the product in grams, and as a percentage of the recommended daily maximum. Supermarkets which display the traffic light system say it is easier to understand and process at a glance. The comparatively complex numbers in the GDA mean little to the average consumer, so they are susceptible to be influenced by other information. Those supermarkets who display GDAs have an opportunity to use a behavioural ‘nudge’ to make their customers feel better about their products.

The nudge is akin to Batesian mimicry in the natural world, in that the mimic displays meaningless colouration which is meaningful in the species being copied. If only GDAs are being displayed, the background to the figures is free to be coloured in as the supermarket chooses. By imitating the traffic light colour scheme, a false impression of the nutritional information may be created. However, this cannot be done so faithfully to the original as to arouse suspicion. A balance must be struck therefore, between activating the traffic light concept in the consumer’s mind, and staying on the right side of the regulations. As such, the colour scheme should remain constant across all products, to avoid accusations of manipulation.

Naturally, the desire will be to make the product appear as healthy as possible. This would result in a uniform green background across the categories, but this nutritional profile wouldn’t be feasible for the vast majority of products, and may not trigger the association with the traffic light system. The nudge therefore should have a mix of green, orange and red to look like the traffic light system, but still have a relatively healthy profile to entice consumers.

The green background should be behind the categories of most concern to the health-conscious consumer – this is likely to be fat, especially for those watching their weight. GDAs are displayed for both overall fat and saturated fat, and unsurprisingly these two values often fall into the same traffic light colour. To create a realistic profile therefore, both types of fat should be green. This creates a problem though – if the colour scheme is presented to the authorities as meaningless,  they may ask why some categories are the same colour and some different? A solution is to make the shades of green slightly different, so that the effect is sufficiently similar to the traffic light system, but not too obviously.

The remaining categories of salt and sugar must be given orange and red to complete the effect. It is arguable which is more important to the consumer. Sugar may be in the high category for more products, including relatively healthy products like fruit juice, yoghurt and other products containing fruit. If the sugars are derived from fruit (like fructose), they aren’t as unhealthy as added sugar (like glucose), but can still push a product into the red zone. For these reasons it is more realistic and desirable to use the red background for sugar than salt. This leaves salt on the orange background, which as the indicator of a medium amount, is believable for a majority of products.

The GDA system also includes a category for calories, which is useful for the mimic, as at this stage it looks suspiciously like a traffic light system, with only red, orange and greens. Giving calories another colour makes this less conspicuous. Blue is good as it is unobtrusive and close to green, implying healthiness. In fact, consumers may think that calories are separate, and the other categories are using the traffic light system, as the calorie category is the only one not given in grams. To make the association with the traffic light system less obvious, the colours should be toned down slightly, perhaps by using pastel colours, and the greens could be made blue-greens.

Overall then, the GDA mimic of the traffic light system would suggest a product is high in sugar, medium in salt and low in fats. This is a profile which is feasible for products like breakfast cereals, some bakery items, biscuits and desserts, and some ready meals. But the effect could be successful even for products which obviously don’t fit the profile – a customer is unlikely to examine every category, and may just want to know how much fat is in a product.

Looking at a figure of 17% for the fat GDA, would the average consumer know if this falls in the low, medium or high category for a snack, or for a ready meal? Might they be influenced by the background colour of the figure, by thinking the traffic light system is being used? Even if a consumer doesn’t think it is being used, there is a wealth of evidence to suggest that decisions are based largely on subconscious processing. Might the background colour have a subconscious effect on health judgements of the product? Could the pastel colours be used to connote lower levels of each nutrient, as is commonly done with low-sugar/fat products and healthy options?  These are easy questions to answer empirically, and companies answer exactly this sort of question through market research.

If a supermarket were to use this mimicking technique, it may lead its customers to make unhealthier choices than they otherwise would, and think that the products they buy are healthier than they actually are. This would lead to a double whammy for the supermarket: its customers enjoy their food more, and believe they are eating more healthily than they are. The supermarket’s food is thus more associated with both tastiness and healthiness than that of its rivals – two huge advantages in the competition for customers.

The GDA system on its own is complex and difficult to understand compared to the traffic light system. When combined with traffic light mimicry, however, it could become actively misleading, at the will of the supermarket. The solution is simple: make the traffic light system mandatory. The nudge may only work on health-conscious consumers, and may only have a small effect each time, but across millions of consumers over the course of years, the cumulative effect could be enormous. After all – every little helps.

Take a placebo if you know what’s good for you

Prescription placebos used in research and pra...

Alternative therapies are often written off by sceptical rationalists with the traditional refrain that they are ‘no better than placebo’. What little good research and meta-analyses exist on the topic do confirm this to be the case, thus debunking the holistic practitioners’ magical claims. What this dismissal glosses over is that the placebo effect is a lot better than nothing.

Vast swathes of research have found that the effect works across physical and mental conditions, using different forms of sham treatments, from sugar pills to surgery. Researchers have played with the properties of treatments, finding out that four sugar pills per day are more effective than two at removing stomach ulcers, and that injections of saltwater are more effective than pills at relieving pain. Even seemingly small details add to the effect: the effect is strengthened by pills that are bigger, branded, and more expensive.

Alternative therapies have already figured out these details, however. By being allowed to operate in an unregulated market, they can concoct whatever remedies take their fancy, and consumer tastes and demand selects the most popular. Incongruously, their business environment is closer to unfettered capitalism than that of the big pharmaceutical companies. In addition to identifying the most effective placebos, alternative therapies offer the added bonus of giving the patient his/her choice of treatment. The importance of feeling in control of one’s treatment is gaining currency at the moment, reflected in the emphasis on patient-centred care. Evidence shows that a feeling of control is associated with better outcomes. This suggests that patients who choose a certain placebo may do better than patients who are prescribed the same one. Open up the NHS to market forces, and increase patient choice: does this sound familiar?

The NHS currently funds placebos in the form of complementary healthcare, though of course neither party in this arrangement describes it in such terms. This includes paying for the pseudoscientific flourishes unique to each therapy, such as sourcing unnecessarily exotic ingredients. Surely then the NHS could save significant amounts of money by funding an in-house placebo program, pared down to the simple elements of the effect? Two objections spring to mind: perhaps the mystique of alternative therapies is essential to the effect, and at the very least the patient must be unaware he/she is taking a placebo, meaning the NHS would have to lie to patients. The latter option really isn’t an option, as it would erode trust in the doctor-patient relationship.

A paper published last year provides hope that these problems may not in fact exist. Researchers randomised patients with irritable bowel syndrome (IBS) to an ‘open-placebo’ group, in which patients were given pills they knew to be inert, or to a control group which was given no treatment. Crucially, the pills were presented as having been effective in the past, thus creating the expectation of an effect. Patients given the open placebo did indeed report significantly increased global improvement scores, adequate relief and reduced symptom severity. This finding urgently needs replication across other medical conditions, but the fact that the effect on adequate relief was even bigger than in double-blind IBS trials is very encouraging.

This then is evidence that the placebo effect remains, even when patients are told they are being given a placebo, without any explanation of how it may work. Expectation of effectiveness is the underlying driver, rather than belief in a treatment having a specific mechanism. This applies equally to alternative therapies – the stereotype of people trying them being new age types isn’t the whole story. Many people trying them don’t believe the claptrap, but are desperate and willing to try anything that appears so successful.

Similarly, the nocebo effect illustrates how the expectation of side-effects can lead to their existence when a placebo is taken. Clinicians therefore have the power to heal or hinder with the same placebo: whatever prediction they make of it becomes a self-fulfilling prophecy. Ethically, this seems to clear the way for clinicians to be able to say, truthfully, that the placebo they are prescribing should make you feel better.

Placebos on the NHS would put an end to the bizarre monopoly which alternative therapies enjoy over the use of the placebo effect. Current regulation means that this quite well understood scientific phenomenon can only be used by those who reject scientific input into their therapies. This disadvantages certain groups who don’t want to or can’t use alternative medicine – rationalists on principle, and people who can’t afford it. And for all the similarities, a commitment to placebos would be a commitment to a type of medicine which is the very opposite of alternative therapies: evidence-based medicine.