Recently, I regurgitated something the Internet mustered up on Holistic Grazing. Allan Savory put forward the theory that productive and sustainable land management can involve periods of heavy grazing and trampling by large numbers of cattle. By doing so, the vegetation is ‘reset’ periodically, the land’s water retention capacity increases and as a bonus, you get to harvest animal protein (milk and meat) from the cattle. Before long, James McWilliams responded in a Slate article that he finds Savory’s claims outrageous and unsupported by evidence and that holistic grazing would never work on a significant scale. So there’s scientific progress for you: one person says “A”, another person says “not A”, and in the process of bickering we hope to gain some new insights.
What makes it so difficult to get a clear “yes” or “no” on the question if holistic grazing works? Like most really relevant societal issues, holistic grazing is a complex in which incredibly many variables interact. From a methodological viewpoint, this makes it difficult to research. In order to prove or disprove the validity of a complex concept such as holistic grazing, you would ideally have to attack the problem from three angles. Below, I will take holistic grazing (as I understand it, and probably imperfectly so) as an example, but the essence is the same for the scientific research of any complex issue.
Firstly, there are the fundamental mechanisms on which the greater intended effect relies. These are relatively simple relationships that can individually be investigated. In the holistic grazing, these include the relationship between trampling of the soil and the supposed increased absorptive capacity of the soil, and the relationship between grazing and the regeneration of vegetation. In controlled studies, these relatively simple relationships can be studied quite well. McWilliams draws into doubt some of the basic underpinnings of holistic grazing, citing research that has apparently proven that increased trampling results in decreased moisture retention of the soil. If holistic grazing is a house, then one of its cornerstones was just exposed as being made of gingerbread instead of brick. But the stones don’t tell the entire story of the theory. Let’s take a look at the cement.
Secondly, there is the issue of how the individual mechanisms interact with each other. I mentioned grazing (as a way to renew vegetation) and trampling (as a method to enhance water retention of the soil) as basic mechanisms. Together, they should (according to the holistic grazing theory) result in the same area sustaining a larger amount of vegetation. Here, systematic research becomes a bit more challenging. In this example, we have three parameters: grazing and trampling as supposed causes or independent variables, and the amount of vegetation as a supposed effect or dependent variable. As a researcher, you would have to look at all permutations of the independent variables. This boils down to running four bits of research: (1) no grazing and no trampling, (2) no grazing, but with trampling, (3) grazing, but no trampling and (4) both grazing and trampling. In all four cases, observe the effect and decide if there is a relationship between the causes and effects. Of course, to reach meaningful results, you would have to repeat the measurement lots of times so you are not just measuring serendipitous effects – hooray for statistics. Not to forget that you would have to study the results over a longer period of time (say, a decade or even more) to establish the long-term effect. With two independent variables, this is already a lot of work. But in complex theories, many more variables interact. Of course, as the number of variables increase, the possible interactions between them increases exponentially. Research becomes such a daunting task that it isn’t even funny anymore.
Thirdly, there is the issue that makes it virtually impossible to give an easy answer to a seemingly straightforward question: exogenous variables. Above, I wrote about variables and relationships within the system under study. But a system such as a tract of land with vegetation and cattle on it does not exist in a vacuum. It is inseparably connected with everything around it. In fact, the boundaries of the system relevant to holistic grazing that I haphazardly defined just now do not actually exist in reality. When researching a complex issue, we tend to take a piece of reality, draw an imaginary line around it and call it ‘a system’. For holistic grazing, you could try to do this a couple of times in different places worldwide; which is exactly what Allan Savory has done and from which he has collected the supporting evidence for his approach to land management. But even then, there is virtually no way of telling if the effect you observe is the result of the hypothesized relationships and not caused by some external influence. Unless you manage to repeat the experiment many, many times and control external influences – conditions that in a real world setting virtually cannot be met.
So it seems that science is a dead end street when it comes to really complex problems – which the most relevant ones often are. Or is it? It certainly is if you want a straight answer. I think that the straight answer can only come from a vision: that such-and-such is the way things are most likely to develop and so-and-so are the actions that we should take right now to prepare ourselves for the future. I am convinced that science can most certainly inspire such a vision and result in more accurate, dependable visions on the future.