Sense about Science ? equipping people to make sense of science and evidence
What does 'natural' actually mean?
We all think we have some idea of what ‘natural’ is, whether it’s the green meadows we pass by on the train or the fresh and colourful vegetables we pick out in the market. But our countryside and the food we eat are the results of centuries of agriculture.
How far away from ‘natural’ are we? Is an heirloom tomato more ‘natural’ than modern varieties? How are ancient grains different from the other grains we eat today? Do pesticides reduce insect populations below the ‘natural’ levels we’d expect if there was no farming? Do you know what natural really means?
Our plant science panel supported by the BBSRC, Nature Plants, leading research institutes and learned societies has already tackled topics from genome editing to neonicotinoid pesticides. Now, as debates over the ways we improve our crops wrangle on, we have brought together a panel of experts for one of our live online Q&As on what ‘natural’ actually means.
If you have a question on a plant science-related issue then get in contact with our plant science panel via Twitter, @senseaboutsci using #plantsci, or email us at firstname.lastname@example.org.
1. "When did our food supply become 'un-natural'? Agricultural revolution? Green revolution? Industrial revolution?" (Dan Curtis)
Mike Ambrose: "For me this is the agricultural revolution [around 10,000 BC]. Until that point, food supply was based on sustainable foraging, which can be considered a natural food supply chain. This all changed when our early ancestors started cultivating certain wild plants and making plant selections to adapt them for their use and for cultivation. This process is known as domestication.
There is nothing natural about clearing a site or altering a landscape to create fields for growing crops. The process of domestication is still very much working with natural variation and a natural process until you stop and realise that the crops of today, while well-adapted to cultivation are no longer able to survive or compete in the wild."
2. "With conventional breeding, nature corrects mistakes. Can humans really be trusted to take over that role?" (Online comment)
Prof Ottoline Leyser: "Conventional breeding involves humans selecting variants that meet human requirements. A good example is selecting crop plant varieties that do not shed their seed, but instead retain them on the plant for ease of harvest. This is a very unnatural trait that would not persist in the wild, because seed dispersal would be severely compromised. Crop plants only survive because of the unnatural environment we provide from them in agriculture, clearing away the competition and planting and tending them in the field. In other words, crop domestication involves human selection replacing natural selection. The results are very far from nature, and there is no sense in which any 'mistakes' in this process are 'corrected' by nature."
3. "In a society where sustainability and food security is becoming increasingly acknowledged as the driving factor – how does the panel feel about “organic” produce, and how it is still commonly perceived by consumers as being better for both people and the environment?" (Siobhan Gardiner)
MA: "I am all for consumer choice so if people want to buy organic then that’s fine, but it’s not a choice that I make. The reasons for people making that choice are many and varied. Organic systems are generally seen as involving less inputs and therefore ‘more natural’ so playing out to subjective norms. Sustainability and food security require a more objective approach and generally I feel there is insufficient awareness of the absolute necessity of having to dramatically increase the unit area productivity of our major crops in order to feed the world's growing population, which is something that organic farming cannot deliver."
OL: "The stated aims of organic farming are excellent. However, in my opinion the rules governing organic farming prevent the aims being achieved. This is because the rules involve blanket bans on entire categories of things, such as all "artificial chemical fertilisers" or any crop variety produced using GM. This cannot possibly be consistent with the aim of delivering the best in environmental protection. If environmental protection is the driver, then that alone should dictate what is and what is not allowed, and this obviously requires evidence for the specific agro-ecosystem in question. The idea that every fertiliser or every GM crop variety will be less good for the environment than all the alternative options is not credible. I am much more convinced by the approach of LEAF (http://www.leafuk.org/leaf/home.eb) where the goals are the same, but the focus seems to be much more straightforwardly on delivering sustainability, no holds barred."
Prof Sarah O'Connor: "I strongly believe that we need to be careful about what types of pesticides we put on our food, and how these chemicals impact our health and the environment. But the organic label does not mean 'pesticide free'. Copper sulfate is a common chemical used in organic farming, and it is highly toxic."
Dr Helen Roy: "Ensuring responsible food production is a major challenge on a planet occupied by more than 7 billion people. Protecting the environment should be a key priority but there are often conflicting demands of food production and biodiversity. The solutions are not simple. The science is complex. We know that biodiversity loss and environmental degradation is a consequence of many interacting factors such as habitat loss, climate change and pollution. However, it is important that we gather robust evidence to ensure the agricultural practices we employ are the best possible for the environment while providing the best possible food. Along the way it is essential that consumers are informed through effective science communication."
Prof Robbie Waugh: "For me the problem with organic is not about whether it is better or worse than intensively farmed produce, it's about whether organic could feed the population and at a price we could afford. Along with the majority of the scientific community - I don’t believe it could. So – it may well be that there are higher levels of various nutrients because of the mode of cultivation (i.e. agronomy), but yields are low and only a select few in the population can afford to purchase organic because it is so much more expensive to produce. As far as environmental concerns, you have to remember that organic producers still use natural chemicals to protect against disease and some of these chemicals – e.g. Bordeaux mixture – contain high levels of copper which is itself pretty toxic. Of course organic growers often take other actions to help protect against disease, but if disease gets hold, it becomes very difficult to eradicate and can lead to crop failures. Can you imagine the impact on our food security if the whole wheat or potato crop failed because we couldn’t control the spread of a devastating disease? This is what spurred the Irish potato famine and I for one don’t want to return to days like that. So for me, sustainable agriculture is about a reaching a balance between cost and production required to meet the demands of the population. If this could be achieved organically – I'm sure most would support it. Unfortunately it can't."
4. "Vinblastine is used to treat cancer - it's from plants - does that mean it's a 'natural' remedy? Does that mean it's less safe?" (Mari Peters)
SOC: "Before vinblastine (and other plant-derived medicines like taxol) are used in the hospital, they go through an incredibly rigorous purification and testing process. A patient does not receive a crude plant remedy containing vinblastine. Instead they receive a highly purified form of vinblastine. So plant derived medicines that are used in European and US medicine are not really any different than standard medications in terms of safety."
5. "St John's Wort would interfere with my medication – is this common with natural remedies? What about modern medicines from plants?" (Alex Borthwick)
SOC: "St John's Wort stimulates our bodies to overproduce an enzyme in the liver (called a P450). This liver enzyme modifies the medication that you are taking and causes you to excrete it faster. You may have also heard that you should not eat grapefruit while taking a statin for high cholesterol. This is for exactly the same reason – a compound in grapefruit stimulates production of a P450 in our liver that makes us degrade and excrete the statin from our bodies too quickly. It's very hard to predict which drugs/molecules will interfere with other medications: some are fine, others cause problems. So check with your GP before taking any over the counter herbal remedy."
6. "I have celiac disease and have to eat a strict gluten free diet. There are many news reports linking the consumption of GM foods to an increased risk of developing a gluten intolerance or sensitivity. What scientific evidence is there to substantiate this claim?" (James)
OL: "I am not aware of any evidence at all linking GM food to gluten intolerance. There has been some speculation that the herbicide glyphosate could be linked to gluten intolerance. I am not an expert on this area and so I can't comment on the quality of this evidence. However, I can say that any evidence linking glyphosate to gluten intolerance should not be confused with a link to GM food. Glyphosate resistance is one common GM trait, which is used in conjunction with glyphosate treatment as a method to control weeds. However, many GM crops have nothing to do with glyphosate and much glyphosate usage has nothing to do with GM. Glyphosate is widely used in horticulture and can be readily obtained in gardening centres round the country."
7. "Are there any crops that could sustain the world population in their wild, 'natural', forms?" (Prys Ellis)
MA: "That’s a tall order. I think that people are already cropping from a large number of wild plant species in many parts of the world. Wild plants are adapted for survival and if you think about wild grasses they have very small seeds, are hard to extract and are not highly productive so they are very limited in what can be harvested and used. Having said that, wild species are still immensely valuable as part of the extended genepool for crop improvement as sources of valuable traits. The key is to understand the genetic basis of these traits in these wild species and look to introduce them into one of our major crops which have been developed to deliver maximum output."
8. "Are less intensively-bred crops, like ancient grains and heritage varieties, better or worse at resisting diseases?"
RW: "I don’t think there is any strong evidence to suggest that heritage varieties are better at resisting disease. The point is that diseases are changing all the time as they become able to overcome the defences that exist in certain plant varieties and plant breeders are continually struggling to introduce new sources of disease resistance that has not yet been overcome, or trying to introduce multigenic resistance (so called quantitative resistance) where many genes of relatively small effect work together to stop disease. The idea is to ‘stay ahead of the curve’ so that before a new disease becomes prevalent there is already material in the pipeline that will show good levels of resistance. Many heritage varieties are just that, because they wouldn’t have sufficient levels of disease that became prevalent when they were widely cultivated."
9. "Why do we have seed vaults for ancient seeds if 'natural' isn't important?" (Helen Regan)
HR: "We live in a time when the environment is changing rapidly. Seed vaults provide an important way of conserving biodiversity, particularly when the threats to biodiversity are escalating through environmental change. Of course we should be doing all we can to preserve species in their natural habitats (so called in situ conservation) but seed vaults and gene banks (so called ex situ conservation) provide an insurance policy. It is inspiring to think of the resources preserved in elaborate seed vaults, millions of seeds representing important crops which provide opportunities to ensure future food security."
10. "I know we get some medicines from plants (aspirin). Do you think there are more of these 'natural' medicines left to find?" (Lucy Berkley)
SOC: "I definitely believe that there are lots left to find! If you look in the scientific literature, you can see thousands of papers describing the discovery of new compounds that are isolated from plants that show very promising anti-cancer, anti-viral, anti-inflammatory etc. activity. One thing to bear in mind is that it is hugely challenging for a compound that shows a promising activity in the laboratory to be brought into the clinic. This is true for both compounds isolated from plants and molecules that are made completely synthetically. It takes time (and money) to demonstrate that a compound is safe and effective for human use."
11. "Are all naturals organics and vice versa?" (Ekemini Obok @ekemini_obok)
OL: "Organic farming is a method of farming widely perceived as "more natural" than conventional farming. As you can see from answers to previous questions "natural farming" is an oxymoron. Farming is a profoundly unnatural process involving the deliberate manipulation of the environment and of plant genetics to provide safer, more nutritious and more abundant food. We have been doing this for 10,000 years. So from that point of view organic and conventional farming are equally unnatural."
12. "'Natural' food (at least food that is marketed as such) seems to be growing in popularity – why do you think this is?" (Lucy Berkley)
SOC: "Well, natural is a vague term and could mean many things! And I suspect that the food marketing experts take advantage of this. However, to at least partially respond to your question, I think as we learn more about food and our metabolism, the benefits of eating whole, unprocessed foods are becoming more and more clear. For example, eating an orange has much more benefit than taking a vitamin C tablet. The natural orange contains hundreds of compounds (many of which we know little about) that show extremely promising health benefits."
13. "Are organic 'natural' pesticides and fungicides really better for the environment or human health?" (Chelsea Snell)
HR: "There are so many different ways in which pests and diseases can be controlled. It is essential that people know what they are using and consider the potential impacts on the environment and/or human health - even when the product is labelled as 'natural'. Perhaps the most ‘natural’ way is to enhance the predators, parasites and pathogens that occur naturally within an ecosystem. There are many ways in which this can be achieved, for example by creating suitable habitats through agri-environment schemes within farmland to support these beneficial organisms. For all methods of pest control it is important that practice is based on sound scientific evidence and more often than not a variety of methods are required to ensure sustainable control."
OL: "There is no basis for assuming that naturally-occurring pesticides are less damaging to the environment or human health than synthetic ones. In terms of pesticides used in organic farming, one of the most controversial examples is copper sulphate-based fungicides, such as Bordeaux mixture. Copper is a heavy metal which is toxic and extremely persistent in the environment, so although there are strict limits on how much organic farmers can apply, I think it is likely that similarly controlled use of a synthetic fungicide would be more sustainable in many situations."
14. "Are there any reasons why we should be looking to eat food which is more 'natural' (eg fewer synthetic chemicals)?" (@RebeccaNesbit)
OL: "Plants are extraordinarily good at making chemicals. They make thousands of them. Many of them are highly toxic and contribute to defending plants from herbivory. There is no reason why the chemicals made naturally in plants would be any less toxic than ones made in a factory by humans. To decide which chemicals are safe to eat and which ones are not, we have to rely on direct evidence. It is not possible to make assumptions or even useful predictions based on whether or not the chemical is made in nature."
15. "Is kale more natural than its close relative oilseed rape?"
MA: "Kale is a member of the cabbage family (Brassica oleracea) and has been in cultivation for some 2000 years. Oilseed rape (Brassica napus) is a much younger crop; it only came into cultivation in the mid-19th century and arose from a natural hybridisation between Brassica oleracea and Brassica rapa. So you can see that they both share some common ancestry. You will see this most clearly by not just looking at the seed, but if you let kale go to flower they will look very similar in morphology. As oilseed rape has undergone less domestication, one could argue that it is closer to the wilder natural forms and better able to survive in the wild than kale. However, I would argue this is only one criteria on which to assess them."
16. "How far back would you have to go before the potatoes we were growing were 'natural'? Is it possible to buy some of these old natural potatoes? Are they edible?" (Jane Marshall)
RW: "Potatoes were originally domesticated in South America, most likely in Peru, Bolivia and Equador at high altitudes, some 8000-6000 years ago. They were being eaten then in South America and probably were what is now considered ‘natural’. They arrived in Europe in the 16th century directly from South America, probably through Spain and Britain, and had to quickly adapt to the environmental and climatic conditions found in Europe at the time. They had to change their day length sensitivity and probably after many years of harvesting tubers and seed and replanting each year they became adapted to our conditions. However for much of their early existence they were not considered a staple food except for poor people and animals, the better off didn’t originally eat potatoes. This as we know was different in Ireland where they became a staple for the general population, until the Famine. The Famine was caused by the widespread cultivation of a single clonal variety called Lumpers which was susceptible to late blight and when this struck it was devastating, wiping out entire harvests across the country, because all potatoes grown were susceptible. Only when different selections that were resistant to blight were introduced did production start to stabilise. Since then, artificial crosses have been made and new varieties have been bred. They are ALL natural. If you want to get your hands on the original types introduced from South America you may need to go to gene banks where they are maintained. Derivatives are available in speciality seed catalogues – but they are generally old or heritage varieties, not original introductions. Some breeders are going back to Andean potatoes for certain characteristics and you can therefore sometimes find significant ‘bits’ of the original potatoes in modern varieties."
17. "What about 'bio-based' raw materials from fermentation using modified microorganisms? Not from petroleum, but GMO. Natural?" (@kzrt)
SOC: "The term 'natural' isn’t regulated or strictly defined, so its hard to say whether compounds made by GM microorganisms can be called natural or not. Personally, I would have no problem using or eating a product that came from a genetically modified micro-organism. There is work in progress that aims to produce saffron in a yeast – this would make saffron much less expensive and more widley available. I would definitely buy this spice produced this way!"
18. "Since selective breeding means that no food is in its natural state, do you think a label stating the product is "natural" could actually mean anything useful to consumers?" (Sarah Jose)
RW: "Who said selective breeding changes a food from its natural state to an unnatural state? Does cooking? I don’t agree with this concept at all. Some will consider natural more to do with the way the food was produced or incorporated into foodstuffs rather than how it was derived - but this in itself is difficult to specify accurately (e.g. if it was planted by a farmer in a field is this natural or unnatural? I could easily argue that it's unnatural). I think a label stating that something was natural would raise more questions than answers (because of how it is defined) and does not convey anything useful to consumers."
19. "Is biological control inherently safer or more natural than using pesticides?"
HR: "Biological control comes in many different guises and involves a diverse range of species. There have been many success stories involving classical biological control (in which an exotic predator or parasite is introduced) to combat pest insects and weeds. Conservation biological control, whereby native predators and parasites are enhanced within farmland, is gaining popularity and is in many ways the most natural of all control methods. However, sometimes the distinction between chemical and biological control is blurred. The bacterial pathogen Bacillus thuringiensis (Bt) has been used successfully to control insects in a number of crop systems but the activity of this pathogen is based on toxic crystal proteins which it manufactures. Bt is often referred to as a biological pesticide."
20. "I've heard there's a new bumblebee species in the UK. Is this because of human interference? Will it become invasive?"
HR: "There are more than 2000 non-native species established in the UK and only a fraction are considered problematic. Unfortunately the small number that are considered to be invasive cost the economy £1.7 billion and perhaps more importantly pose a serious threat to the environment. The new bumblebee – the so-called tree bumblebee Bombus hypnorum is not considered likely to become invasive. It was first recorded in the UK in 2001 and has spread rapidly but no-one is quite sure how it arrived. It is fantastic to think that this small bee has expanded against the back drop of declines reported for other bumblebees. It is a species associated with open clearings in woodlands and thrives in urban parks and gardens. So human interference, in terms of urban habitats, appears to have benefited this species. Private gardens in Britain cover about 270,000 ha and gardeners have the opportunity to ensure these provide habitats for many other species of bee and indeed other wildlife."
21. "I've heard lots of people say that breeding any organism for food, fuel, sport or for pets is effectively genetic modification. Isn't this a bit misleading?" (davidsouthafrican on the Guardian)
OL: "This all depends on how you define genetic modification. Conventional breeding without a doubt modifies the genetics of the organism in question. The genetic changes we have introduced in this way have much more profound effects on the organism that anything we have done in a GM crop so far. These classical breeding approaches have often involved the insertion of extra DNA, because it turns out that the genomes of most organisms have many so-called transposable elements. These can move about the genome, and have been a major driver of genetic change during evolution by natural selection and also domestication of crops by human selection. This means that there is nothing much unique about modern genetic modification, where a specific piece of DNA is inserted into the genome of a crop to introduce a specific new gene, except perhaps the range of genes that can be added. This is why there is a growing momentum to regulate new crops according to the trait or gene that has been introduced, rather than the method by which it was introduced."
22. "Some consumers worry about 'man-made' food additives but aren't many of these found naturally in the food we eat anyway?" (Chelsea Snell)
SOC: "This is correct. Some dyes or flavours that are added to foods are found in nature. Sometimes a synthetic or artificial additive is called artificial, but it is exactly the same as a natural compound. For example, vanillin is made synthetically, but it is exactly the same molecule found in the plant – so in my opinion, it really doesn’t matter whether you are eating the synthetic or the natural version – it's the same molecule.
In other cases a compound that is added to food is in fact 'natural' in that it has been isolated from a plant but I would argue that the molecule has been so highly processed that calling it natural is meaningless. High fructose corn syrup is isolated from plants (a natural source), but it is so highly processed and added to certain foods in such ('unnaturally') high levels that I personally avoid foods with large amounts of this ingredient."
23. "I'd like to know how different today's wheat is from that traded 8,000 years ago - and how different they both are to 'natural' wheat." (Prateek Buch)
MA: "There was a great news story today on evidence of wheat coming to Britain 8000 ago. Staying with this story, the evidence was for Einkorn wheat (Triticum monococcum, AA), which was domesticated out of the wild species (Triticum boeticum, AA) so it was already very different: larger seeds and more productive. The wheat mostly grown in the UK today is bread wheat (Triticum aestivum, AABBDD), which was domesticated many thousands of years later following two further natural hybridisation events. Interestingly, as a result of this process, bread wheat contains within it the genome of the ancestral Einkorn wheat.
The presence of the other two genomes (BBDD) in bread wheat mean that the two forms look very different. The leaves of bread wheat are wider and larger and their spikelets have many more florets. Bread wheat grain sizes are much bigger and they have a different profile of seed storage proteins.
The wild ancestors of wheat are all in effect wild grasses with very small grains which are tough to extract. It’s a wonder when you look and work with them that early man ever found enough to make a meal out of."
24. "Do advertising standards have a definition of 'natural'? Should they?" (@RebeccaNesbit)
OL: "I think we can all get way too anxious about what we should and should not eat. That's why we can be persuaded by flashy marketing to pay lots of money for food that is no better for us or for the environment than lots of other food. I like the Michael Pollan quote 'Eat food, not too much, mostly plants'."
25. "How much has wheat/corn/barley changed since domestication?"
RW: "The domestication process surprisingly involved changes to a relatively small number of genes. Using barley as an example, probably the most important were mutations in a pair of genes called BRITTLE RACHIS 1 and 2 which changed the barley flower (inflorescence – called the spike) from one that dispersed the grain at maturity to one that had lost that ability and retained grain on the spike. You can imagine it's a lot easier to harvest grain by collecting mature spikes holding twenty grains than picking up individual grains from the ground after they have been dispersed. Not surprisingly, early farmers increasingly selected plants where the grain was retained on the spike – some of which they planted again in the coming season. By doing so the frequency of adhering spikes increased in populations.
Once that problem had been solved they noticed that some spikes carried three rows of grain rather than the two rows found in wild barley. These six-row barleys contained a mutation in a gene called SIX ROWED SPIKE 1 and converted the sterile lateral florets found on the mature two-row spike into fertile florets – thus generating six rows of grain. Of course when barley was domesticated – much of it was used as a food – so early domesticators also identified grains where the hull (the leafy organs surrounding the grain) were not as tightly bound as the wild type progenitors. In these grains – when the dry hull separates from the starchy grain and the plants are known as ‘naked’. This is caused by another mutation in the NUD gene.
Since these original domestication events, however, barley has migrated with the farmers that grew it to as far north as the arctic circle and south to the Equator. These regions have very different climates from where it came from, so through a process of mutation and selection barley has become a very widely adapted crop. It remains very similar to it wild ancestor (and can still be easily intercrossed), but exhibits characteristics that allow it to grow and flourish in a wide range of environments. Current varieties are higher yielding and better quality than wild varieties. But without doubt, during the process of domestication many good versions of genes that may be important for future cultivation – because they provide tolerance to stress or resistance to disease – have been left behind."
We ran out of time to answer all the questions we got during the live Q&A. Here are the remaining questions answered by our plant science panellists.
26. "In the UK, the phrase 'natural' in foods is restricted to foods that have ingredients produced by nature, not the work of man or interfered with by man. But is any of our food produced by anything other than the work of man?" (Paul Rodriguez)
Dr Hanna Tuomisto: "The regulations by the European Commission and the Food Standards Agency in the UK define the criteria for the use of the term “natural” in food labelling. According to those standards, the term “natural” can be used to describe single foods to which nothing has been added and has not been processed in any other way except with some traditional processing practices. “Natural” claim cannot be used for novel foods, genetically modified foods or foods containing ingredients that are the product of the chemical industry or extracted by chemical processes. However, most of those regulations are related to food processing practices without setting limitations to the agricultural production practices. Products from conventional agricultural systems that use synthetic fertilisers and chemicals for plant protection can be called “natural” according to the legislation. Therefore, it is true that the legal definition of “natural” does not necessarily correspond with the general understanding of the term by the public."
27. "How do we counteract the misuse of the word 'natural' in nutrition dialogues, discussions and 'tips' in the media?" Gabriella Everett (@gabiieverett)
Dr Alison Clark: "Gosh, this is a hard one to answer as people will often misquote and misuse the word 'natural' in nutrition dialogues and the media. How to prevent/counteract it - good question?! I suppose the first thing would be to highlight this as an issue to professionals who are engaging in such dialogue and encourage them to be aware of the misuse and think wisely before such terminology."
28. "I'm an Australian who studied ecology at university, so I've learned a lot about how Aborigines managed the land since they arrived many thousands of years ago. A lot of Australia's grasslands and open woodlands were maintained by regular burning, which is still practiced in many areas. Does this mean those habitats are not really natural? When I visited the Brecon Beacons and Dartmoor national parks, I was surprised by the fact that they're used to graze stock. Because this has been happening for so long, should we consider that to be a 'natural' ecological process?" (Richard Boyne)
Dr Alan Jones: "You are correct about the key role of fire as a factor in shaping the Australian landscape. Similar human-driven ‘land management’ processes have also occurred here in the UK for thousands of years, including fire and grazing in in upland areas and lowland heathland. These adapt ‘natural’ processes and enhance them to our benefit. In each case, we hold plant communities in a successional state called a plagioclimax. Whether such adaptations are ‘natural’ or not depends on your viewpoint; for instance, some argue we should allow nature to take its course and return protected areas to a ‘pre-human’ state – a process often termed ‘re-wilding’. Interestingly, however, some traditional human managements may mimic pre-human ‘natural’ processes – eg coppicing versus megafaunal browsing damage in woodland. Ultimately, we need to consider that whatever decisions we make, they will have significant impacts on our landscape, so we need to evaluate what we are managing for. In the cases of burning, grazing and coppicing, these can enhance biodiversity, carbon storage and water regulation, but only if conducted appropriately. Too much of either, particularly in sensitive habitats, can have opposite and detrimental effects."
Our Q&As answer the questions people put, which may mean that some parts of a subject are covered well and others not. If there is an issue that you think is not tackled, you are welcome to send a follow up question to our plant science panel