Tag Archives: British 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


Powering the Future

I had the pleasure of spending yesterday evening at the Royal Society Summer Exhibition. I’d recommend it to anybody if you want to dip in to what British science is about and what it can do for people. To a geek like me it was fascinating to hear first-hand from young scientists about the things which enthuse them. But it also has some deeper messages, especially for where I think government should be putting its money in the forthcoming spending review.

Prof Brian Cox visits Tokamak’s Faster Fusion exhibition stand at the Royal Society Summer Science Exhibition

Prof Brian Cox visits Tokamak’s Faster Fusion exhibition stand at the Royal Society Summer Science Exhibition

I learned more about the immune system in a 15 minute discussion with one of the young scientists than I had learned in a whole career working in biology (although I am not an immunologist). This conversation squeezed my intellectual juices to the extent that I felt sad that I couldn’t just give up all the complexity of making science work to develop better public policy and get in to the lab. It’s the laboratory, big-or small-scale, that is the engine house where new ideas emerge. It’s a rewarding experience for anybody to look at the immune system. It leaves me in wonder at the complexity of structure that can emerge from a process of natural selection. The immune system  is much more complex than anything that mere humans have managed to engineer.

Perhaps there is nothing more fundamental than the question ‘how did life evolve life?’. The really interesting problem is that for life to exist there needs to be a mechanism that induces self-replication of the molecules that code for proteins. We know that this sits within DNA, but DNA cannot replicate without a ribosome which is a small, high complex, organelle that exists within cells just to perform this function. So, the question then arises, “how did ribosomes come in to existence?” Whoever can answer this question is pretty close to answering the most fundamental question of all – how did we get here?

I also have to put in a strong plug for those exhibits that reflectedFlu Defra’s science and that were supported directly or indirectly by Defra’s funding. One wasabout influenza viruses. Many vertebrates (including humans) aresusceptible to infection by flu viruses and many of these viruses are able to infect more than one species. There are perhaps a couple of hundred variants of flu viruses depending on the form of two proteins on the surface of the virus, the ‘H’ and the ‘N’ proteins. Birds seem to be able to host almost all these variants and, thankfully, humans just a few. Some are almost benign in that they only cause very mild disease but others are deadly.

A problem is that different strains of each variant can cause different severity of disease. Knowing all this is vital to allow us to be able to design better control systems including understanding paths of infection and designing vaccines.  The Spanish flu pandemic of 1918 killed about 50 million people – more than were killed in the First World War. That was the H1N1 variety. Not to be too melodramatic, there are plausible scenarios where, in today’s world of mass travel (which leads to rapid transfer of viruses around the world) we could all succumb to influenza. We need to be on our guard!

Another fascinating Defra science project concerned the importance of meat. Some who have read my recent blogs will know that I am sceptical about meat as a source of nutrition when farmed through intensive rearing systems. However, what this exhibit shows is that through careful management of farming as a whole system and the use of pasture that cannot be used for direct human consumption, cattle producing beef is one of the most efficient ways of turning this in to food for people.

This is about matching, for example, the variety of grass that is grown to the digestive system of the breed of cattle that are eating that grass to maximise the transfer efficiency of grass to beef. In a sense, this is a very different kind of genetic engineering where one is being clever about matching the properties of the grass with the properties of the cattle. When one then starts to build this around ensuring that soils are sustained, rivers don’t become polluted with effluent and we minimise the amount of gas given off to the atmosphere as methane, ammonia or N2 one is starting to understand that the complexities of a farming system begin to match those of the immune system (see above) – and are just as fascinating!

However, for me, the highlight was the exhibit from Tokamak Energy. I learned that ‘tokamak’ is actually a Russian acronym, because the technology was invented in Russia. However, what excited me was that the company was using current technologies to build their machine – they felt they could do this without having to wait for any new basic discoveries to emerge – and they had a business model that was attracting investment. I wish them every success.

I have not been able to mention all the exhibits I saw all of which have their own wonderful stories to tell. However, I am struck by just how fundamental to the future and successes of humanity are all the examples I have given here. Many other exhibits also fell in to this category. From the fundamentals of how life forms through to the building of a machine that could power our future development, it’s a glorious accolade to British science.