Tag Archives: science

The value of scientific opinion?

The European Food Safety Authority (EFSA) has published guidance on how to incorporate uncertainty in to scientific assessment[i].  On the plus side, this is a thorough attempt to bring objectivity to the description of uncertainty and to minimise subjective opinion. On the negative side it could eliminate the opinion of scientists from the policy debate. Where uncertainty exists, this could result in risk-aversion in policy-making.

As a scientist, I believe it is vital that public policy is underpinned by a foundation of evidence. However scientists must also acknowledge that policy makers look through many lenses when making their decisions and science needs to play its part as one of these lenses. It is therefore important that the relationship between uncertainty in the evidence and risk to policy is understood.

While scientists are used to dealing with the uncertainties inherent within their evidence, these uncertainties present a real tension when being used to underpin the more black and white, yes or no, world of policy . Government departments, like Defra, use evidence to guide rather than to determine policy in areas of uncertainty.

Scientific uncertainty comes in two basic forms – aleatory and epistemic. Aleatory uncertainty is the natural variability in a system and is often irreducible even through research. For example, the yield of wheat per hectare from British farms has a tendency to vary among years. In contrast, epistemic uncertainty is what we don’t know, or gaps in our knowledge and is amenable to being reduced through research. For example, wheat yields from British farms have been, on average, static for about the last decade and we don’t know why. It is important to understand the difference between these forms of uncertainty in the context of evidence assessments for policy making.

This is well illustrated by the recent EFSA document which is aimed mainly at documenting epistemic uncertainty. Evidence assessments are now used widely to produce ‘scientific opinion’ in an attempt to advise policy-makers about the scientific consensus view on a subject. EFSA uses them a lot – e.g. for assessing the safety of pesticides or GM organisms. The Intergovernmental Panel on Climate Change (IPCC) is another body that has done this on a massive scale to provide an assessment of the evidential basis for anthropogenic climate change.

These assessments needed to include opinion because we know that the way evidence is generated through the scientific process is itself subject to aleatory uncertainty. For example, the results from many experimental studies carried out in the fields of psychology and biomedicine are known to be unreliable[ii]. Including just the epistemic component of uncertainty using this literature could produce a biased assessment. Among all the studies done in a particular field, it can be impossible to discriminate the reliable from unreliable studies using systemic, rule-based assessment. In the environmental sciences, where studies are often impossible to replicate and where less reliable inferential methods are often used, this problem is probably even more profound.

Within this context, the EFSA attempt to corral and upgrade the assessment process by being clearer about how uncertainty is being dealt with is commendable. However, nobody should imagine that this will solve the problem about how scientific evidence is used to define the risk associated with food in Europe. Beliefs and values are as prevalent within scientists carrying out assessments as they are in non-scientists. The kind of processes being suggested by EFSA, while necessary, still should not ignore scientific opinion. The EFSA guidance carries the risk of systematising the expression of uncertainty by focussing purely on the state of knowledge, the epistemic component of uncertainty. Recognising the existence also of the aleatory components of uncertainty in scientific assessments is essential. It brings humanity to the discourse between science and society, and science and policy.

[i] Guidance on Uncertainty in EFSA Scientific Assessment, EFSA Scientific Committee, doi:10.2903/j.efsa.20YY.NNNN, http://www.efsa.europa.eu/sites/default/files/consultation/150618.pdf

[ii] Nosek, B.A. et al. Estimating the reproducibility of psychological science. Science: 349  DOI: 10.1126/science.aac4716


A different angle on diversity

I strongly believe everyone should have equality of opportunity in our society regardless of their gender, age, ethnicity, class, disability or sexual orientation. There is clear evidence that societies which have lower income inequality enjoy better mental and physical health, higher life expectancy, achieve more in education and their work lives and are generally happier, than those societies which, even though they may be wealthy, have a greater disparity between the richest and the poorest.

Discrimination – on any basis – is the antithesis of equality and we have to work hard to counter issues that foster unconscious bias. Being a middle-aged, white, heterosexual male from a pretty comfortable middle class, northern European background, it’s not often I feel that I am the subject of discrimination, but a couple of recent experiences have opened my eyes to some forms of bias that I believe need to be put on the table for discussion. I believe they were genuinely unconscious in nature but they reflect something that is deeply rooted in the world within which I work.

Diversity at work

I am a civil servant and an academic. I have two jobs, one in Defra as its Chief Scientific Adviser and another as a professor in biology at the University of St Andrews. Straddling the divide between these two cultures gives me a useful perspective on the extent to which these two cultures tackle inequality in the workplace. As a scientist, I like numbers and indicators and the proportion of women in the respective organisational structures I work for is a convenient indicator.

In Defra, 53% of the work force is made up of women, although at senior levels this drops to 37.9%. Universities, as many know, have a steeper hill to climb. Although 45% of the work force is composed of women, only 27% of academic staff are women and only 17% of professors are women.  At least both these sectors slightly better reflect our society than our Parliament where only 29% of MPs are women!

However statistics do not say much about underlying biases in behaviours. I have said in the past that government has a tough job. Commerce tends to tackle solvable problems that lead to profit. In academia, one can choose the problems one tries to solve; some academics will focus on those that are tractable while others might take a few more risks but in that case failure has few consequences.

In government, however, there is rarely a choice about the problems one chooses to tackle. Civil servants have to pick up the problems that often have no clear solution, that nobody else wants, and that are often ‘wicked’ in nature. The insolvability of many problems of this type requires the cultivation of a special form of intellect and capability.

An unfair view

The policy and evidence professionals in the civil service are excellent at what they do. Part of my job is to scrutinise the civil service and advise about how it can better generate the evidence it needs and how best to use it. I would be the first to say that the system of government is far from perfect, but I object to the view sometimes projected from academia that government is second class. I came across this attitude recently in two contexts, (I won’t give details to spare the blushes of those involved) and although I’m sure they had no idea of the implications of what they were doing or saying, nevertheless it betrayed a prejudice.

In essence they said that government could not possibly be excellent at its work. These guilty parties were so entrenched in a way of thinking that they could hardly even bring themselves to use the word ‘excellence’ in the general context of government. The Research Excellence Framework, one of those much-maligned civil service initiatives has both strengths and weaknesses but it has perhaps reinforced a false view within the academic community that academia has a majority on the word ‘excellence’. This is, of course, rubbish.

The thoughts and acts that fuel this kind of discriminatory attitude are rooted in the same behaviours that drive discrimination of all types. They concern self-interest from those of low self-confidence. They are a close cousin of schadenfreude but are about denigration for the purpose of self-aggrandisement. Civil servants, who often have skins of leather, tend to take this on the chin, but I see the constant, low level disparagement of the work of civil servants, whether policy officials or  scientists, as an issue that needs to be highlighted and resisted.

While this kind of pernicious bias persists, it is difficult for academia to improve its diversity record and get its own house in order. My point, of course, is not about eliminating criticism and challenge of the work of civil servants, but about making sure that it is founded on achieving the joint objective which is to make things better. Diminishing the credibility of others based on unfounded bias is as unfair and malevolent as any other form of prejudice.

Join the charge against plastic bags

I have spent much of my research career in far-flung places across the world. While there are some places where it is quite hard to find the imprint of man, in general, one does not need to look very far before the signs start to appear. More often than not a piece of plastic signals this imprint. I have even seen plastic debris on an iceberg in Antarctica – for me this was the tip of the iceberg in more ways than one.


My interest in marine mammals and seabirds has brought me up close and personal with the impact plastic debris has on our planet. The scale of the problem can be startling. I have studied whales in the tropics and sometimes it looked like the whales around me were swimming through a thin soup of plastic.


A recent study suggested that around 90% of seabirds had plastic in their stomachs and I have seen first-hand the other consequences plastic has on our wildlife. I have removed fishing nets from around the necks of seals. I have seen the plastic debris regurgitated by albatross chicks littering their nest sites, a seabird washed up dead on a beach because it had an elastic band around its bill, and others strangled by the plastic from a six-pack. I have even removed a young Arctic fur seal from a carrot sack. I have seen how these plastics gradually cut through the skin around the necks of these animals, leading to infection and a slow death, often from starvation.


The effect that plastic debris has on our environment goes beyond what we can see. While it’s hard to precisely quantify the full effect, we know that plastics reach far and wide within the ecological systems of our world. It’s not just larger pieces of plastic that are a threat to our planet. Microplastics are the microscopic break-down products formed once ultraviolet light and environmental abrasion get to work on plastics. These end up in the stomachs of zooplankton, like copepods, that are unable to distinguish between them and their real food. As the zooplankton gets eaten by bigger species – fish, squid, whales and the like so the microplastics move up the food chain. If we look at the harm macroplastic can have on some larger animals we shouldn’t turn a blind eye to the possible effects of microplastics.


So, with this visible and invisible damage being done to our world, I support plans for retailers to start charging for plastic bags in October, because I’m sure that the charge is going to have a real impact on the amount of plastic that enters the marine environment. It will give me and others across England that nudge we need to remember to bring that bag with us next time we head to the shops and recycled where possible when it comes to the end of its life. My confidence in the impact that the charge will have is grounded in solid evidence. In Wales for example, carrier bag use has dropped by nearly 80% as a result of their 5p charge. It has been a similar story in Scotland and Northern Ireland who have also introduced the charge. In future, those economies that are going to thrive will be the ones that have learned the art of resource efficiency and, in my view, this starts with sensible, proportionate measures like this charge, to reduce the unnecessary generation of waste. This is not ‘anti-growth’, as I suspect some people might suggest, but it is making the case that growth doesn’t require the wasteful use of resources.


As a scientist, my job it is to weigh the evidence and provide dispassionate analysis. But setting aside my duty as a scientist, there are some things that we should just do, because we have a moral duty to do so as a citizen of this planet. For me, protecting our environment and fellow inhabitants of the planet is one of those duties, and we can help to honour it simply by cutting down on our plastic waste. I find myself getting annoyed when I hear people saying what the overall cost of this very small individual sacrifice will be to the economy when they do not, at the same time, assess the benefits that will accrue if we all help just a little amount. The benefit from us doing our bit will far outweigh any cost. And in time, I hope there will be no need to charge for a carrier bag because the very idea of avoiding the creation of unnecessary waste will be deeply engrained in our culture.


The most important thing to remember here is that this really is one of those times where each and every one of us can make a real difference. When disposing of these horrible plastic collars that come with six-packs, I take a pair of scissors to cut them up because never again would I want to walk on a beach and find a strangled bird and have to live with the idea that maybe it was my carelessness that had led to such suffering. And next time I head to the shops I’ll do my best to remember to bring a bag along with me. As a fellow citizen of this planet, I ask you to join me.

Which bee to keep?

Hairy-footed Flower Bee Anthophora plumipes ©Natural England/Allan Drewit

Hairy-footed Flower Bee
Anthophora plumipes
©Natural England/Allan Drewit

Bees often hit the headlines. Where birds once ruled supreme, the bee is the rising star of the conservation movement. The beneficent, busy bees make our world work for us by pollinating our crops and some provide us with honey.

During a recent visit to a firm in the City, I was scanning the surrounding buildings and picked out two bee hives set up on a ledge in the vertiginous face of a nearby building. Defra has a bee hive on its roof and our little friends busily exploit the nectar in the nearby London planes around Westminster. In spite of the sting in its tail, we have embraced the bee.

A lot of information passes by me on a daily basis but occasionally something jumps out at me. Recently, it was the juxtaposition of a scientific paper published in Nature Communications and a draft report that I had to review. The paper was about pollination with information about species loss from Britain.

The paper reported the remarkable discovery that about 80 per cent of crop pollination was provided by only two per cent of bee species. Meanwhile, the report listed all the rare species that might disappear from Britain in the not too distant future.

Without seemingly realising it, the authors of the scientific paper recapitulated a rule of nature which says that abundance distributions tend to follow something called power laws.  They occur in a huge diversity of situations: the number of words in languages, the number of people in relation to their wealth, and the energy used by animals and plants in relation to their body size. Power laws are all over the place.  They apply to the distribution of values of cars on the roads of Britain – you see very few expensive Ferraris, but lots of cheap hatchbacks. A chap called Preston wrote a seminal paper in 1962 showing that species abundances tended to follow these power laws. There are lots of rare species and just a few abundant species.

So, why did this connect in my mind with the messages I picked up about species loss? Well the dilemma the pollinator paper highlights is that most of the rare species listed in the report possibly facing extinction in Britain are likely to be functionless. On what basis could I advise about which species to keep – just the two per cent of bees that provide 80 per cent of pollination; surely not?

The science of ecology has known for a long time that species come and go. Studies by luminaries MacArthur and Wilson in the late 1960s suggested that species that inhabit islands do so. Since the world is made up of islands of a sort, whether in a sea of water or of cereal fields, their conclusions have broad implications for how to interpret species presence, absence and extinction. The species in any one place are a combination of the long standing residents who have adapted to the local environment and the opportunists.

The two per cent of bee species that provide 80 per cent of the pollination are likely to be such opportunists who have coped with the changing landscapes mainly brought about by agriculture. Those listed in the report as under threat of extinction from Britain, although not necessarily from elsewhere, are the losers in this game.

So does this new knowledge guide us towards a more informed kind of conservation? It defines the difference between two doctrines; one of species protection and another of functional importance. This is a spectrum and our individual values place us somewhere between its two extremes. I like species that are unusual and I also see a need to have productive, functional landscapes. Can the two be compatible?

The doctrine of function is played out most strongly through the lens of economics. A growing school of thought attempts to place a formal valuation on assets like species. By those criteria, the 98 per cent of species that contribute only 20 per cent of the pollination services have relatively little utility. Some environmental campaign groups quote the eye-watering large financial value placed on them by economists to support the case for conserving pollinators, but this has a different perspective if it applies to a few per cent of all species. Those who adhere to the doctrine of species protection will say that the same two per cent of important species today might not be the same two per cent needed in future. Maybe we need to protect them all just in case? The low-value 98 per cent of bees that don’t help much towards the pollination of our crops might have other roles we don’t yet see.

These views sit at either end of the spectrum. Of course we don’t want to lose rare species, but we may also need to take species utility into account. We could compromise by defining better ways to construct our landscapes but that will mean some hard choices. Whatever choices we make will favour some species over others and building a rational basis for those choices, as for example the current work on natural capital is tending to do, will be important. Science has a lot more to do to make the case for those we don’t want to lose and those we need to keep.