Monday, December 28, 2009

On Not Screaming As Loud

Quite a few writers over the years have said that vegetarians choose to eat only plants because they don't scream as loud when they are wounded or killed. Not so, says recent research discussed in this NYT essay by Natalie Angier; plants not only effectively "scream" but have some fairly effective active "defenses" against their "predators":
Just because we humans can’t hear them doesn’t mean plants don’t howl. Some of the compounds that plants generate in response to insect mastication — their feedback, you might say — are volatile chemicals that serve as cries for help. Such airborne alarm calls have been shown to attract both large predatory insects like dragon flies, which delight in caterpillar meat, and tiny parasitic insects, which can infect a caterpillar and destroy it from within.
Enemies of the plant’s enemies are not the only ones to tune into the emergency broadcast. “Some of these cues, some of these volatiles that are released when a focal plant is damaged,” said Richard Karban of the University of California, Davis, “cause other plants of the same species, or even of another species, to likewise become more resistant to herbivores.”
Angier goes on to describe some of the various mechanisms employed by plants. Some are ingenious (I use the word in a casual sense, not meaning a product of consciousness but rather "seeming clever to a human observer"); others are quite simple. See the essay to capture the flavor (ahem) of some of the tactics. But none of them... not one that I saw listed... causes even a raised eyebrow to any vegetarian who bothered to stay awake during a decent high school biology class. It's Nature-green-in-leaf-and-branch out there; even the most elementary understanding of classic descent with modification should lead one to nod one's head at each example.

So does this influence the typical sprout-eater? Is there, after all, no moral imperative in this new information that compels one who loves conscious life to avoid eating "higher" plants as well as animals? It depends on a lot of assumptions made by the sprout-eater. For example, I do not see this defense mechanism, wonder though it may be, as being more a manifestation of anything I'd call "consciousness" than, say, your immune system... and the imperative for me not to eat you alive is implanted (ahem) in me with a firmness that simply could not move me to avoid eating a plant. (I also eat some things that are neither animal nor plant, so this question can be applied to other kingdoms.) For me, the question is not, "is it right for me to eat a living thing," but "is it right for me to eat a living thing with a degree of complexity supporting consciousness," a question with more dimensions than can be simply resolved. I'll leave that resolution as an exercise for the reader.  :-)

(H/T Bruce Schneier.)

1 comment:

  1. Interesting but not a surprise to an avid gardener. You constantly see things going on in the garden that tell you,if you are paying attention, that plants are actively managing their little world.
    You know me as more of a 'moral carnivore' than a 'sprout eater' but I agree that knowing plants have active defenses against predation doesn't automatically make them conscious but it should make the eater more aware of the fact that the plants like animals are living things and deserve our respect and gratitude for their contribution to our lives.



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