Reductionist science in agriculture and horticulture

ABSTRACT

Science ensures that explanations and predictions about the biological and physical worlds are verifiable, while also providing an approach that enables improved understanding to develop and be permanently recorded. There are several terms in common usage that describe the approaches used in scientific research, but at the extremes, words such as ‘reductionism’ and ‘holism’ are now frequently encountered. While singular reductionism can result in key relationships and linkages being missed, holism appears to ignore the need to identify how confounding factors can affect the quality of understanding derived from complex systems. Here we suggest that science is not a simple dichotomy of reductionism versus holism. Instead, it comprises a more fluid and complex mission. However, within multidisciplinary agricultural and horticultural science one regularly finds words like ‘systems’, ‘integration’, and ‘unifying’. Reductionist science is certainly part of the pursuit of holistic solutions to problems, not least in transdisciplinary research.

KEYWORDS:

• Scientific research
• reductionist
• holistic
• multidisciplinary
• transdisciplinary

Introduction

Science is a socially organized and institutionalized form of praxis where publicly available knowledge claims are scrutinized by peers and critically tested against empirical phenomena. The claims are derived from a multiplicity of methods and aim to provide rational explanations and understandings of our world. (Kaiser and Gluckman 2023, Looking at the future of transdisciplinary research, Centre for Science Futures, p. 51)

Science is the methodical study of the structure and behaviour of the physical and biological world through systematic observation, experimentation, and the testing of theories. It now involves recorded measurement and confirmation of repeatable outcomes. Through these activities knowledge is established, thus science represents a process for acquiring enduring knowledge. It defines a universal language, and one that traverses cultural boundaries. It welcomes and can accommodate a range of understanding such as Mātauranga Māori (Māori knowledge), whilst also providing a mechanism for that knowledge to be challenged and grown. At its heart, science has been driven by curiosity. Its development has been discussed in some depth by Kaiser and Gluckman (2023).

Clearly some aspects of science have resulted in unintended consequences, such as the eutrophication of waterways, accumulation of DDT in soils and antibiotic resistance. Associated public mistrust has resulted in increased questioning, but ultimately solutions are developed by reductionist scientists and the integration of these results with revised practices.

Scientific progress is never static, although at times progress is slow and even contentious. Regardless of its pace, science requires the ability to establish new findings and insight in the context of what is already known.

There are several terms in common usage describing the approaches used in scientific research to achieve improved knowledge and outcomes. At the extremes, the words ‘reductionism’ and ‘holism’, are often encountered, suggesting that these are part of diametrically opposing research approaches. However, within these so-called extremes one also finds scientists using words like ‘systems’, ‘integration’, and ‘unifying’, while perhaps contrastingly referring to the ‘weight of evidence’, or ‘current thinking’ and ‘consensus’. Such expressions suggest science is not a simple dichotomy of reductionism versus holism, but instead it is a more fluid and complex mission that by its nature accommodates uncertainty, opinion, and its inference, and leading to well-informed opinion.

Irrespective of the terms used, we contend that there is an irrefutable requirement for all steps to be founded on reductionist scientific approaches in improving scientific understanding and its effective application. It is only knowledge created from profound and detailed research (both empirical and mechanistic) that leads to the development of new scientific insights, and almost certainly new questions. If the simplest relationships cannot be tested and shown to be robust, then any effort to create a broader holistic overview on a subject is likely to be flawed. That said, a notable feature of fully informed holistic approaches is that they can also offer the potential for the development of new understanding. At times, detailed reductionist science from a range of disciplines needs to be integrated into a ‘bigger picture’. In effect, we believe science absolutely needs reductionist approaches, but at times it also requires knowledgeable people, applying their methodologies to identify synergies and appropriate areas for integration. By taking intersecting strands of reductionist science, integration can result in a new direction or broader perspective. It needs both reductionist and integrative approaches in tandem, to grow and advance knowledge.

Despite this, an examination of terminology surrounding different approaches to agriculture shows that the term ‘conventional agriculture’ (or horticulture), has become weaponised (or referred to dismissively) by the proponents of ‘alternative approaches’ (Sumberg and Giller 2022). The same pattern has appeared in science, whereby those who regard themselves as having holistic approaches, can too easily disregard reductionist science as narrow, old-fashioned, and irrelevant to understanding complex systems. The ‘reductionist’ tag is thus used pejoratively. Indeed, it has been stated that ‘to call someone “a reductionist”, in high-culture press if not in serious philosophy, goes beyond mere criticism or expression of doctrinal disagreement; it is to put a person down, to heap scorn on him and his work' (Kim 2000).

Richard Dawkins (1986) wrote ‘Reductionism is one of those things, like sin, that is only mentioned by people who are against it’. He goes on to suggest that nobody is really a reductionist:

The non-existent reductionist – the sort that everybody is against, but who exists only in their imaginations – tries to explain complicated things directly in terms of the smallest parts, even, in some extreme versions of the myth, as the sum of the parts! The hierarchical reductionist, on the other hand, explains a complex entity at any level in the hierarchy of organisation, in terms of entities only one level down the hierarchy; entities which, themselves, are likely to be complex enough to need further reducing to their own component parts; and so on.

New Zealand is a global leader in agricultural and horticultural science research and development, driven by the critical importance of these sectors to the economic well-being and environmental quality of this country. Further, New Zealand’s position of leadership in agricultural and horticultural production is the result of discipline experts (who could be called reductionist scientists) providing the wherewithal and ability to integrate their detailed scientific research findings into holistic viewpoints. This has led to developments such as Integrated Pest Management (IPM) practices in New Zealand’s primary industry sectors. IPM can be defined as an approach to pest management that uses comprehensive information on the life cycles of pests and plants and their interaction with the environment, along with a combined range of pest suppression systems, such as plant resistance with which to manage pests economically with minimal hazard to people, property, and the environment. In this sense, IPM is therefore a holistic approach that is underpinned by reductionist science. For IPM to work, underlying reductionist research must never be dismissed as unnecessary.

As with the tension between holism and reductionism, we strongly believe the apparent rift between conventional and alternative agriculture is unhelpful and negatively impacts any advances and improvement. We also contend that the belief by some that there is an acceptable binary approach between either holistic and reductionist approaches impedes scientific progress, leading to misunderstanding, unnecessary duplication, and distraction. Undoubtedly, agricultural and horticultural advancements have involved the uptake of findings of reductionist scientists in specific disciplines who, without exception, work alongside specialists in other disciplines. Single discipline advancements, which sometimes might appear mundane, and possibly irrelevant to the uninformed, are nearly always integrated for the benefit of systems analysts and developers (i.e. informed holistic thinkers), and ultimately for our primary food producers.

The New Zealand challenge

In the context of New Zealand pastoral agriculture, ‘reductionist’ pest management research has led to the now obvious recognition that, although of similar appearance, pasture ecosystems in New Zealand are significantly different (Goldson et al. 2020; Caradus 2023a; Caradus et al. 2023) to the ‘evolved’ and well-established native grasslands found globally, and that this likely explains the occurrence of exotic pest outbreaks (Goldson et al. 2020). In a similar vein, expertise in soil science and agronomy resulted in a re-examination of the nitrogen needs of small seed crops in New Zealand (Rowarth and Archie 1994). This then resulted in the ‘targeted approach’ of nitrogen application, which has since become part of best practice crop management. Molecular biology (which led to the genetic engineering revolution of the past 25 years and that has been argued by some to epitomise the reductionist approach to science [Fang and Casadevall 2011]) combined with breeding expertise, has provided a basis for evaluating and interrogating the intended and unintended consequences of this biology in the development of new crop cultivars. It has also indicated the possibility of more robust yet flexible methods of regulating and monitoring GM crops (Caradus 2023b, 2023c).

In these three areas, the underlying and original science have by necessity been reductionist. However, there is the danger that such work can be dismissed by adherents to holism, as at best ever-increasing research into scientific minutiae of no consequence or value (‘luxury research’ or ‘more and more about less and less’). At worst, in New Zealand and globally there are claims that science creates consequences that are contrary to the well-being of humanity (e.g. https://english.umd.edu/research-innovation/journals/interpolations/interpolations-spring-2011/genetic-engineering-serious#:~:text=Genetically%20engineered%20organisms%20pose%20an,to%20kill%20millions%20of%20people; https://www.iisd.org/articles/analysis/tackling-hunger-nitrogen-fertilizers#:~:text=Synthetic%20nitrogen%20has%20also%20caused,fish%20and%20other%20aquatic%20organisms.). In the above cases though, the results of the reductionist science have been examined in a broader context to understand interactions, the balance between risk and benefit, the potential for unintended outcomes and their possible amelioration.

We, therefore, contend that in agricultural and horticultural science in New Zealand, reductionist research has been vital to improving the understanding of the complexity and impact of examples such as imported beneficial insects, plant nutrient needs, or the value of imported plants for breeding. The knowledge of discipline minutiae and context have ultimately enabled New Zealand farmers and growers to improve their practice and productivity.

How reductionist science has informed holistic practices in New Zealand

New Zealand successfully uses pasture-based production systems to immense benefit in generating export earnings. However, the species involved are exotic to New Zealand. We have therefore adapted and optimised pasture systems based entirely on these exotics, including in some cases, microbes. This has resulted in resilient production largely through reductionist science.

For example, there is an ongoing challenge from pest species that enter New Zealand as consequence of biosecurity breaches. These incursions can severely limit pasture plant production and persistence. They threaten our economic well-being, as both the lack of pasture plant and natural enemy diversity, results in there being little biotic resistance to invasive species (Goldson et al. 2020). Consequently, these pests can build up to levels that are often far higher than those found in their native ranges. In contrast, there is indeed a New Zealand-native natural enemy fauna, which has evolved over tens of millions of years. The fauna are, however, embedded in our native ecosystem and have virtually nil interaction with introduced pest species (Goldson et al. 2020).

In effect the native ecology has been disrupted, and apart from ceasing all pastoral production practices, and abandoning the basis of our economic wellbeing, there is an inevitable need to address the ongoing challenges. Science-based restriction of the effect of biosecurity breaches from pasture pests is an immense task. However, and paradoxically for the same ecological reasons associated with our isolated island nation status, some biological control agents introduced to combat the pests can work extremely well, as they too are not impacted by their own suite of natural enemies. Thus overall, the circumstances of New Zealand’s pastures are quite different from those found in locations elsewhere, and where pests and their natural enemies have co-evolved in complex species-interaction networks. An immediate conclusion from the reductionist science points to the possibility of increasing the plant diversity in our pastures to lure native natural enemies to control the pests. However, detailed reductionist studies have shown that this does not lead to the hoped-for pest suppression. This is because New Zealand’s natural enemy fauna has been found to remain firmly in their indigenous ecosystems and rarely venture beyond their native plant communities (e.g. Tomasetto et al. 2017; Goldson et al. 2020).

Recently Stewart et al. (2023) have provided another example of the benefit of reductionist research. These workers were able to conduct multidisciplinary analyses of historical (sealed) seed samples collected in 1917. Through seed curation, they provided a picture of the quality of seed lots at that time. Perhaps unsurprisingly, the ‘old’ seed was quite different to that of the modern ryegrass seed industry, which is based largely on crops grown on arable land in Canterbury. The modern seeds have been bred to be highly productive in, and better adapted to, New Zealand conditions.

Of further interest, close ‘reductionist’ inspection of these old seed samples detected the presence of insect fragments indicating the widespread presence of the Argentine stem weevil (Listronotus bonarinesis (Kuschel)). This extended the 1927 first record (Marshall 1937) of the weevil in New Zealand by at least ten years, and indeed based on its distribution, the pest may well have been established in New Zealand by the turn of the twentieth century. Reductionist science can therefore reveal hitherto unknown historic detail. Perhaps unexpectedly, the 1917 perennial ryegrass seeds also showed levels of the common toxic Epichloë endophyte (and associated alkaloids) comparable to those rates found in the 1980s and 1990s in samples from old pastures across New Zealand. The authors therefore speculated that this again could indicate that the weevil had been in New Zealand for some time prior to 1917, and that this had then exerted positive selection pressure favouring endophytic ryegrass (e.g. Easton 1999).

At a broader level, through soil, pasture, and animal management, in combination with selection of plants and animals, New Zealand has created greenhouse gas (GHG) efficient pastoral production systems for milk (Mazzetto et al. 2022) and meat (Mazzetto et al. 2023). Low GHG emissions per kg of product were the unintended consequence of the focus on production efficiency. The gain in efficiency has come about in most part through typically reductionist, and certainly concerted single-discipline approaches to improve pasture plant and ruminant animal health and resilience. This extends to genetics and breeding, fertility, management, and longevity, all within the topo-climate of the farm operation and within the political (local and national) constraints, plus those imposed by markets. Newly proposed holistic systems must match this improved conventional agricultural performance, for the GHG footprint of pastoral production systems to remain efficient. There is, however, already evidence to suggest that this is not the case for meat production (https://ourlandandwater.nz/outputs/regenerative-agriculture-value-proposition-final-report/).

Despite such evidence, some environmentalists and others are active in claiming a ‘better’ way to approach food production, espousing one that ‘works with nature’, the implication being that science-based agriculture somehow works against it. In this case, reductionist science does enable us to garner a better understanding of how nature may be reacting to changes in those measurements that are associated with increases in efficiency.

Opinions contrary to current science-based production systems are epitomised in the current promotion of regenerative agriculture (RA) in New Zealand. For example: ‘One of RA’s distinguishing features is the holistic pursuit of continuous improvement, not only on environmental but also on social, economic, and cultural outcomes, both within and beyond the farm gate’ further ‘While RA is informed by the many predecessors of alternative agricultures, unlike them it does not preclude any particular practice if it is needed to facilitate the transition of the agroecosystem to a state of increased health’ (Grelet et al. 2021). Here it needs to be asked if these statements are based on fact, or aspiration? This is important because one of the immense benefits of reductionist science is the accumulation of accepted (i.e. peer-reviewed) knowledge in searchable and publicly available repositories. The methods and metrics developed by reductionist scientists to measure food and fibre production efficiency and environmental footprints could be well applied to include the evaluation of regenerative agriculture. To advance knowledge, future research on holistic systems, such as regenerative agriculture, will need to create accumulated accepted (i.e. peer-reviewed) knowledge in searchable and publicly available repositories.

The tension between reductionist science and holism can similarly be found in medicine. The practitioners of complementary and alternative medicines (CAM), indulge various practices including ‘natural medicine’, herbal remedies, non-conventional medicine, and holistic medicine (https://www.healthnavigator.org.nz/medicines/c/complementary-and-alternative-medicine/). In an article published in the International Journal of Health Science (Tabish 2008) the editor wrote: ‘The list of CAM practices changes continually as CAM practices and therapies that are proven safe and effective become accepted as “mainstream” healthcare practices (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068720/)’. Proving that which is ‘safe and effective’ undoubtedly requires a scientific approach. However, it is notable that within the CAM ‘industry’ fashion can prevail, and the dollar can rule.

The problem with CAM practices approached in anything like holistic fashion, is that it is difficult to identify the various drivers of change. Complicating matters is the placebo effect, which is undoubtedly real in health (Benedetti 2022). Placebo-like factors can also apply to non-medical areas. The positive effect of the encouragement provided by coaches in regenerative agriculture has been documented in Australia (Ogilvy et al. 2018), with regenerative graziers self-reporting higher wellbeing than conventional graziers, despite being under greater financial stress (Francis 2020).

Holistic approaches and transdisciplinary research

Discussion and practice continue to evolve when considering how scientists can interact with other knowledge systems in a constructive way. This has been highlighted recently in a discussion paper commissioned by the International Science Council to provoke reflection (Kaiser and Gluckman 2023). The study highlights how ‘post normal’ scientific contribution (a problem-solving strategy appropriate when facts are uncertain, values in dispute, stakes high, and decisions urgent (Funtowicz and Ravetz 1991)) is needed to address the challenges and uncertainties associated with complex values-laden scientific issues of pertinence to whole communities of interest.

Such situations are sometimes referred to as ‘wicked problems’ (Rittel and Webber 1973) and they are characterised by high levels of uncertainty, ambiguity, having incomplete information and by the presence of value conflicts. There are numerous examples of such challenges including climate change, biodiversity loss, water pollution, microplastic pollution, genetic engineering, chlorination of drinking water, etc. In this context, it is immediately apparent that reductionist disciplinary and more holistic multidisciplinary science cannot singularly provide adequate answers. Rather what is required has come to be known as transdisciplinary research.

The transdisciplinary research approach requires that at the beginning of the design of a research programme, the science component is integrated with the various stakeholder interests including such things as prior empirical observations, traditional beliefs, historical analysis, resource-user economics, existing policy settings, etc. The early combination of these factors and the inclusion of interest groups then provides a way for all parties to dissect complex ‘wicked’ problems and define the appropriate research questions in a potentially actionable manner. Thereafter and often via the testing of various holistic models, appropriate strategies and policies can be arrived at in a way that is recognisable, if not completely acceptable, to all parties. Significantly, the design of transdisciplinary research can enable the avoidance of hubris as to which knowledge or value system is the more important.

It is important to note that Kaiser and Gluckman (2023) state that transdisciplinary research ‘does not replace normal science which continues to be critical for addressing so many issues and for driving innovation in health, environmental management and socio-economic development’. They argue that transdisciplinary research is not undermining reductionist approaches, and that disciplinary excellence that may have been built up over many years remains crucially important to progress. Nor is transdisciplinary research to homogenise accepted scientific research methodology by claiming equivalence with other systems that have their own distinctive characteristics.

Transdisciplinary research seeks to complement disciplinary research with innovative efforts to constructively address real societal problems in the company of diverse knowledge holders and stakeholders. When things get complex (which they almost always are in the real world), there is the need for new effort to construct useful knowledge for understanding and management, and a significant part of this is the development of what are truly holistic models.

A path forward – do not indulge a needless dichotomy

In science, reductionism and holism do not necessarily have to be at the opposite ends of the spectrum. Both approaches can deliver value, but they also have limitations (Fang and Casadevall 2011). Singular reductionism can result in key relationships and linkages being missed, whereas holism can ignore the need to identify how confounding factors can affect the outcomes derived from complex systems. These can include factors that are different, yet produce the same response, or when the same factor can elicit different responses in a different system. Essential indicators can be glossed over, and the power of scientific inference and relationships lost. Such an outcome has been described negatively: ‘When fecklessly performed, systems biology may merely describe phenomena without providing explanation or mechanistic insight or create virtual models that lack biological relevance’ (Fang and Casadevall 2011). Fortunately, these weaknesses are usually ‘cured’ with the passage of time.

Here we emphatically support hypothesis-driven science over qualitative description. The former provides insights into causation, and for science, this is critical for progress. The latter has a place provided it is both repeatable and durable. Agricultural scientists often work in multi-disciplinary teams to ensure that different, and at times reductionist, perspectives, and expertise are brought into play (e.g. Caradus et al. 2023).

The need to publish in science and the moderating force of peer evaluation and review, means that, in practice, isolation is rare. Most peer-reviewed scientific papers now comprise groups of specialists. In agriculture the development and use of sustainable land management systems requires that we work closely with practitioners of other disciplines. However, it is vital that in working with others, the standards of scientific research in the individual disciplines are not compromised via short-cuts towards holism (Bridges and Catizzone 1996). Increasingly scientists must also take broader legal, economic, and social conditions into account. Harsh economic reality often drives what scientists do. If science is not funded, then the practitioners tend to make little progress. He (or she) who pays the piper calls the tune, whether it be holistic or reductionist.

In the last decade, ways have been identified (e.g. Brown et al. 2015; Palmer et al. 2016) that encourage transdisciplinary science, including the development of ‘T-shaped scientists’ showing breadth as well as depth of understanding (Hansen 2010). Such a development suggests that funders, publishers, and institutions have a major role to play in the way they invest in and reward outcomes. Similar comments have been made in New Zealand (Duncan et al. 2020), but evidence suggests that in agricultural science collaboration is the norm: interdisciplinary science (when people with reductionist expertise work together) is recognised as the way to advance understanding and opportunity.

Transdisciplinary research is an interesting case where there is the formalisation of multi-agency research to deal with ‘wicked’ problems. Undoubtedly, by way of continuous inputs by various stakeholders, this uses holistic modelling approaches to test the potential for dealing with complex societal issues. Here by definition, scientific research is part of the pursuit of such holistic solutions, but unfortunately, therein there can be a view that the use of reductionist scientific research is somehow indulgent or old-fashioned. This is unacceptable.

Conclusions

The varying approaches to science endeavour discussed here coincide with the appearance of widely enunciated and aspirational intentions for improving primary production practices in New Zealand. In effect, many feel the need or desire to move beyond the ‘conventional’, if such an approach could be defined or even exists. As an aspiration, this may add value, but with this comes the danger that such intentions may engender the pursuit of ill-advised short-cuts that ignore the robust analysis provided by reductionist science. Accordingly, the pursuit of ‘working with nature’ as discussed earlier, may be based more on ‘feel-good’ factors rather than on systematic, peer-reviewed, and documented findings. Reductionism must not ignore serendipity, but neither can holism. With reductionist science, libraries contain a precise record that allow us to stand ‘on the shoulders of giants’.

Disclosure statement

No potential conflict of interest was reported by the author(s).