CRISPR as Niche Construction: an Aristotelian View

CRISPR (pronounced “crisper”) is part of a system, noticed in certain bacteria, by which a cell can make changes in strands of DNA. This mechanism appears to be a proto-immune system: it enables a bacterium to recognize the DNA of an invading virus, and then to disable that DNA by cutting it. Scientists have harnessed the system to manipulate the genome of other cells. They can, in effect, turn a particular gene off to test its function, or, if that gene is known to produce an undesirable trait, to eliminate it. Further, they can employ the system to insert new genetic material, causing the expression of desirable traits. (For good explanations see the videos below: on the left is a brief overview, on the right is a longer presentation by Jennifer Doudna, one of the inventors of the technique.)

(For other descriptions see this episode of Radiolab; this story from The New Yorker; this story from National Geographic; and this story from PNAS.)

CRISPR has generated excitement—and concern—over the prospect of human intervention into fundamental biological processes; it has been likened to a “word processor” for genomes. Though there are many other applications, e.g. in medicine, the deployment of CRISPR in agriculture is well underway, for example in the development of crops that are drought or disease resistant (see this story by Maywa Montenegro on ENSIA). This is perhaps the most obvious way to make the connection between CRISPR and this blog’s ongoing exploration of niche construction.

Niche construction is the set of activities by which a species interacts with its environment to fashion conditions it needs to survive, thereby influencing the pathway of its own evolution. Agriculture is one of humanity’s central modes of niche construction, and a central agricultural strategy is domestication: the modification of plant or animal species to make them contribute more readily to human survival. CRISPR seems like the final stage of domestication: it seems to promise the relatively fast and inexpensive modification of species to meet human specifications.

The application of CRISPR is likely to strike some readers as creepy at best, if not indeed dangerously hubristic—the latest step in the human domination of nature. It seems to express the anthropocentric attitude that nature is there “for us” as human beings—not only at the macro-level of landscapes we modify and meso-level of individual organisms we consume, but even at the micro-level of the workings of the genome itself.

Historian Lynn White famously associated anthropocentrism with Judeo-Christian doctrine (see this post by Stephen Weldon). But there is another ancient text that also seems to justify human domination—Aristotle’s argument that nature specifically provides plants and animals to human beings:

we may infer that, after the birth of animals, plants exist for their sake, and that the other animals exist for the sake of man, the tame for use and food, the wild, if not all at least the greater part of them, for food, and for the provision of clothing and various instruments. Now if nature makes nothing incomplete, and nothing in vain, the inference must be that she has made all animals for the sake of man. (Politics I, sec. 8)

Aristotle seems, that is, to invoke a kind of natural teleology, or explanation in terms of innate purposes, that might be seen as justifying human use of other species—which are there precisely “for” that purpose. That is the kind of justification that seems to be presupposed in the application of CRISPR.

Philosopher Mariska Leunissen offers a reading of Aristotle, however, which suggests that we are mistaken if we take him to imply, for example, that the physiological processes by which a plant produces its fruit are “aimed at” human nutrition. The purpose those processes serve is intrinsic to the plant—it is the plant’s own reproduction. This is a matter of what Leunissen calls “primary teleology.” However, in practicing agriculture, human beings make use of the plant’s physiological processes for their own purpose of feeding themselves. Thus, they impose a “secondary teleology,” in virtue of which we can say that the plants also serve the (secondary) purpose of feeding human beings.

Leunissen characterizes secondary teleology as “external” to the entity being put to use. There is indeed a goal-directed material process that explains the presence of a field of crops—but that “cause is represented by external agents, that is, by human performers of the art of agriculture” (Explanation and Teleology in Aristotle’s Science of Nature (Cambridge University Press, 2010), p. 38). The goal that is causally explanatory here is the good of those external agents. But this is to say that Aristotle denies that the goal of benefiting humans is somehow present in the crops themselves. “The structures and uses we impose upon natural things through the application of art are always . . . secondary to their own proper natural ends. Nature is not itself anthropocentric; we just use natural things to our own benefit” (op. cit., p. 39).

This distinction between primary and secondary teleology is the basis for Leunissen’s reinterpretation of the passage from Aristotle quoted above. Rather than revealing Aristotle’s belief that nature in some fundamental sense is “made for” human consumption, she holds, the passage reveals Aristotle’s articulation of a specifically human outlook. “The teleology that accounts for the use human beings make of other living beings is therefore secondary: it reveals the perspective of the user, who makes use of what is provided by nature for his or her own good” (op. cit., p. 41, emphasis added). Nature is not “made for” human beings—it only looks like that from the human point of view.

I will return in a moment to this idea that secondary teleology is perspectival. First, though, let me note two ways Leunissen’s reading of Aristotle connects with niche construction.

On the one hand, human niche construction activities can readily be construed as the human imposition of secondary teleology on natural processes. In Leunissen’s words, “human beings are often beneficiaries of natural processes . . . [in virtue of] human art that appropriates those natural processes to serve human ends” (43). But “human art” relies on humans’ cognitive capacity to discern the workings of primary teleology. CRISPR is a paradigm case; its application in agriculture, for example, rests on the ability to understand the biological processes through which organisms attain their purposes, so that those “primary” processes can be made to serve humans’ “secondary” purposes. This example shows how cognition is essential to humans’ capacity to construct their niche. But, as I discussed in an earlier post, Steven Pinker argues forcefully that cognition indeed defines the very character of the niche humans construct.

On the other hand, however, CRISPR also demonstrates that human niche construction can, so to speak, go “deeper into nature” than the primary/secondary teleology distinction initially suggests. For, it can involve more than the diversion of the products of primary teleology from their “natural” ends to human ends—e.g. harvesting the fruit from a tree. Beyond that, CRISPR makes more feasible than ever before the reengineering of primary teleological processes themselves, to make their products conform to human ends. It is not just that humans harvest the fruit—they “program” the tree to produce fruit according to their specifications. In a sense, then, human beings are able to do more than simply use the products of independent nature for their own benefit; they can, in a sense, make nature anthropocentric. Or at least some of it—the part incorporated into the niche they construct. For that is what niche construction involves: a niche is engineered by a given species to yield what that species requires.

But even if we think of secondary teleology as something like the replacement of natural ends with human ends, the lesson Leunissen draws is still important. Again, she holds that secondary teleology is not a feature of nature itself, but instead reveals a perspective on nature, taken by human beings as users of nature (either of natural products or processes). Nature is not in a fundamental sense “for humans,” except from a peculiarly human point of view.

I think that this idea raises deep moral questions, in particular if our discomfort with human domination prompts us to repudiate anthropocentrism. But is it possible for us to abandon that human point of view? Anthropocentrism as a claim about nature, justifying its domination by human beings, can meaningfully be rejected. But what would it mean to reject anthropocentrism as the way human beings see nature? In particular, what other way do human beings have of seeing it? Can we cast off our perspective, and adopt a kind of non-specific (non-species-based) “view from nowhere?” But could that view be the view of a creature embedded in nature—a creature that survives in virtue of its metabolic interactions with a material environment? If that’s indeed what human beings are, can they sustain a point of view that does not represent nature as useable? And if a way of characterizing human beings as natural is to note the status they share with other organisms as niche constructors, can they do other than to materialize that point of view by re-making nature, to make it more useful?

(My thanks to Sevcan Gugumcu for bringing Mariska Leunissen’s work to my attention.)

4 thoughts on “CRISPR as Niche Construction: an Aristotelian View

  1. A very interesting post and, I think, persuasive.
    I would like to note a point that seems to be implied in your post but that is not stressed. That is, it would seem that every time that humans harness the primary purpose of another organism to our own secondary purposes, such usage actually supports and further expresses the primary purpose of that organism. That apples grown in mass orchards for market consumption, to some extent at least, serves the primary purposes of those apples–life, and the transmission of genes, on a scale which would not occur without the human usage.
    CRISPR, and gene editing in general, somewhat modifies this mutual benefit, and in part detracts from it in that the primary teleology of the organisms may itself be altered, but does not seem to remove entirely the mutual benefit of the…symbiosis, if you will. There is still life, and gene expression, expressed on a scale made possible by human activity–even if the organism has been redirected somewhat, it has not been remade entire.
    The degree to which there is some mutual benefit, in terms of organism/human purpose fulfillment, will of course be different depending upon the type of technology and extent of manipulation. It seems to me that this aspect of the inter-relationship also bears upon an ethical understanding of that human activity.

    • Thanks, JD! Your comment made me think of something Michael Pollan wrote about corn some time ago . . . to the effect that human beings were actually doing corn’s bidding, by spreading its genes around so widely. But here’s where I’d love an actual biologist to weigh in . . . if we harvest a fruit, and don’t plant the seeds it contains, is the primary purpose of the plant realized? I don’t know what the right way to think about that is . . . But I agree that there’s some ambiguity with the CRISPR case–and, if the plant is made hardier, I suppose this might suggest that the human intervention actually supports the plant’s primary teleology! A lot to think about here, for sure.

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