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Nassim Taleb, a well-known statistical theorist, and two coauthors (a physicist and a philosopher) have written a working paper in which they purport to show that GMO’s should be banned worldwide lest we flirt with complete ruination, quite possibly the end of humanity. The paper may come to represent sacred writ to anti-GMO activists, as it seems to imply that their position is supported by statistical theory. Ultimately, the paper merely uses statistical theory in the service of rhetoric. It relies on a series of ill-defined dichotomies that the authors use to classify genetic plant engineering into the most “ruinous” category of processes. Among other things, GE is categorized by the authors as a “top-down” technology, it creates global risks and systemic risks, it involves interconnected factors, it is irreversible, its outcomes can be characterized by a probability distribution with “fat tails,” its true risks are “unknowable,” and (worst of all?) it is “human-made,” as opposed to a natural process devoid of human intervention. Perhaps the last condition is meant only to classify processes into the so-called “precautionary approach” to policy assessment, rather than “standard risk management,” but it may reveal something significant about the predisposition of the authors toward human technological endeavors.

The statistical theory presented by the authors is fine, as far as it goes. I have admired some of Taleb’s earlier work, such as Fooled By Randomness, which sought to demonstrate the irrationality of assigning likelihood or even meaning to chance events. Taleb achieved real stardom following the publication of The Black Swan, which warned of severe “outlier” events so rare that they cannot be predicted or even assigned probabilities by humans. The true risks are “unknowable.” Applied work involving “fat-tailed” distributions of possible outcomes, which characterize a wide range of phenomena, is typically supported by prior experience or data, but that is not possible with “ruinous” black swans. Perhaps “extremely long- and fat-tailed” is more descriptive of distributions giving rise to black swans, but of course the extreme outcomes might not be observable ex post.

Taleb, et al, contend that development and cultivation of GMOs carry risks of a black swan ecocide. “Significant” risks? Wait, that involves statistical precision… and data! “Excessive” risks? That implies measurability of one sort or another, not to mention a coherent tradeoff of some kind. “Any” risk of a certain qualitative nature (as defined by the “precautionary approach,” with possible ruin on any time scale)? Of course, the authors are not biologists, agronomists, or geneticists (neither am I), but they claim to have sufficient knowledge to make this judgment:

Ecologically, in addition to intentional cultivation, GMOs have the propensity to spread uncontrollably, and thus their risks cannot be localized. The cross-breeding of wild-type plants with genetically modified ones prevents their disentangling, leading to irreversible system-wide effects with unknown downsides.” [emphasis added]

The article contains a comparison of GMOs to nuclear energy risks, which seems intended to defuse criticism that the authors are simply Luddites. They express guarded optimism that nuclear power-generating risks are “local” in nature, and that problems associated with long-term storage of nuclear wastes are manageable. Clearly, however, those risks are just as “unknowable” as those associated with GMOs. We might add to the list of dangerous human endeavors all research and development of artificial intelligence. After all, a complete ban on AI research would prevent the coming singularity, when we’ll otherwise be lorded over by ruthless, self-serving machines! On a less sarcastic note, I do not discount the possibility of a singularity, but we have the luxury of some time to develop AI in a cautious way, just as we have time to minimize risks in the continuing development and application of GE.

Here is a subset of the many assertions made by Taleb, et al in support of their view:

  • GMOs have the propensity to spread uncontrollably.
  • Healthwise, the modification of crops “impacts” everyone.
  • GMO risks are associated with “fragility” (essentially increasing costs).
  • GMOs imply monocultures.
  • GMOs are qualitatively dissimilar to selectively-bred crop varieties.
  • Selective breeding does not remove crops from their evolutionary context.
  • GMOs remove crops from their evolutionary context.
  • The ecological implications of releasing modified organisms into the wild are not tested empirically before release.
  • The health effects of GMOs have not been tested sufficiently.
  • Incremental varieties of GMOs cause the risk of ecocide to increase.

All of these points are debatable to one extent or another. For example, the common assertion that GMOs promote monocultures reflects a common confusion over GMOs versus adequate crop rotation in mechanized farming. The authors exploit this confusion by linking monocultures and GMOs to reduced genetic diversity (apparently within single crops) and assert that this makes crops more vulnerable to blight, though it is hard to see why this is a foregone conclusion regarding the effects of introducing desirable traits.

More fundamentally, Taleb, et al give short shrift to the idea that there is a risk-reward tradeoff in the use of GMOs, that there are potential benefits and risks of GMO alternatives, and the fact that GMOs do not, in fact, suspend evolutionary processes. If a mutation embodied in a GMO also confers an evolutionary advantage, chances are the mutation will be propagated. If not, the mutation will tend to vanish. This is a safety mechanism provided by nature. Of course, anti-GMO activists seek to conjure images of mad geneticists whipping up monster “Audrey” GMOs with evolutionary advantages, but that is not the character of biotechnology.

Taleb, et al, also wish to equate GMOs with Monsanto. The fact that they are so eager to invoke the company’s name in a negative context within an ostensibly academic paper is a giveaway that the paper is agenda-driven. Monsanto and GMOs are not synonymous, and it is highly misleading to conflate the technology with a single company.

The authors attempt to upstage critics with the choice of the adjective “non-naive” to describe their use of the precautionary principle to guide their policy prescription:

… it is essential to distinguish the PP so that it is neither used naively to justify any act of caution, nor dismissed by those who wish to court risks for themselves or others. The PP is intended to make decisions that ensure survival when statistical evidence is limited—because it has not had time to show up —by focusing on the adverse effects of ‘absence of evidence.’

So, they excuse themselves from bringing anything empirical to bear on the issue of GMO risks because, they contend, “unknowability” is the very nature of the risk/ruin problem, despite the fact that evidence supporting GMO safety does exist, in scads!

Here are a few other sources who have commented on the article:

This post on the NeuroLogica blog questions Taleb’s understanding of biology and genetic engineering. The author, Steven Novella, also notes that Taleb, et al, do not assess the risk of alternatives:

Growing enough food for 7 billion people has consequences, in terms of land use, fertilizer, pesticides, and displacing natural ecosystems. GMO as a technology can potentially add to our efficiency. Banning GMO means relying more heavily on other technologies that may have even more risks.

In addition, Novella says:

… Taleb’s arguments to still come down to hyping the risk of unforeseen consequences due to the inherent limits of scientific knowledge. I don’t agree, however, that GMOs have the potential for global ruin. This is still largely based on a naive belief that transgenes are inherently risky, when there is no scientific reason to believe that they are. …  He failed to make a compelling argument that his principle of zero risk should apply to GMO.

The Motley Fool, generally an admirer of Taleb’s previous work, also believes that he is off-base in the case of GMOs.

David Tribe at the GMO Pundit refutes a couple of assertions made by Taleb, et al. about natural variation and the “track record” of nature as an evaluator of risk.

And at DebunkingDenialism, Emil Karlsson is particularly galled, as he should be, by the comparison the paper makes of the risks of Russian Roulette to GMOs. He writes that Taleb and his coauthors fail to understand basic biology:

In the end, the authors have clearly demonstrated that they do not care about biology, medicine or rational risk analysis. They have negligible knowledge of molecular biology, plant breeding and genetic engineering. It does not matter how much knowledge they have of statistics. If your model is based on flawed premises, then the application and conclusion of that model is going to be flawed. Garage in, garbage out.

Taleb, et al have adorned their paper with statistical theory, and they are certainly correct that “unknowable” risks may be ruinous. But their case against GMOs ignores the substantial body of known evidence on GMO safety. They bring absolutely no evidence to bear to the contrary. Their arguments mislead by relying on false premises and arbitrary classifications. Unfortunately, that won’t stop reverent anti-GE crusaders from heralding Taleb’s “proof” that GMOs are ruinous and must be banned.