The Predation Defense

Lately I've been torturing my family with the question: what would the world be like if all animals were herbivores?  I'm pretty sure the answer is: not as good.  Evolving to hunt makes a species develop all sorts of perceptual and cognitive strengths, and likewise, evolving as another species' prey.  I can't see how a world filled with herbivores, and only herbivores, could have minds as sophisticated and varied.  Predatory mammals would be missing, but also carnivorous birds and fish.  You could wish the world had an intelligent and benevolent creator that would just make clever, diverse, bounteous animals, so the misery of prey being eaten could be avoided, but that's not what our world is like.  In our world as it is, predation is a necessary phenomenon that's shaped species for the better.  There aren't just vastly more species, because of predation, and more "filled" ecological niches, but the species that exist have more and better skills.  Or so it seems--I'd love to have an opinion from an evolutionary biologist given to speculation! 

If predation is a force for good, one thing that follows is that when we think of lions eating zebras, or raptors eating mice, or sharks eating baby whales, we should not disapprove. Few will outright morally condemn a lion but sometimes the reason for avoiding condemnation is not the right one. It's not just that the lion isn't a moral agent, so can't be condemned. A lion is not like a toddler drowning his baby brother--doing wrong, but not blameworthy. It's also not just that the lion, as an individual, needs meat to survive.  The imperative to hunt wouldn't go away, if the lion had a nutritious vegan alternative (faux zebra?). Because (to repeat) predation is a force for good -- without it, there wouldn't be some of the traits, abilities, and species that seem most valuable.   Yes, of course, predation does cause harm to the individual animal eaten, but it's still overall a force for good (in a world like ours, not run by a perfect being).

Now, what does this paean to predation mean for us? We are predators too, of course--since we are omnivores.  If predation is on the whole a force for good, we should at least not be disturbed by the impulse to eat meat or drink milk. These are not the least bit like impulses to torture animals for fun, or molest children, or rape women.  Your inner lion is okay, not criminal or pathological or malevolent.  So much for self-esteem!  We should have it, even as we feel attracted to the smell of barbecuing meat, on a hot summer night.  But should we go further--should we consume meat and other animal products?

I don't think I'd be in worse moral fettle than a lion, if I were running around in the wilderness killing rabbits for my dinner.  As a moral agent, though, I'd have to think through why I was doing this as well as how.   I'd have a duty to kill the rabbits as kindly as possible, and to kill no more than I needed.  Moral agency does, then, make a difference, but not the difference sometimes claimed: I don't have to refrain from killing rabbits, because I'm a moral agent. 

But what about meat consumption in a more typical case? Predation is a force for good in nature, to the extent that it makes nature more varied, bounteous, and mentally sophisticated.  It works wonders in an ecosystem.  But are we humans really still part of an ecosystem? We seem more like destructive aliens, relative to every ecosystem.  Predation is generally a force for good, but predation via domestication, as practiced today by our extremely populous species, is a special case.  Its impact is just the opposite of classic predation--we plus five or six domesticated species now dominate the biosphere, and these species have been bred so that they've lost mental acuity. They're so numerous and dominate so much land that they're a tremendous threat to biodiversity.

When all is said and done, the predation defense for meat-eating seems to exonerate the impulse to eat meat, and even acquit actual meat-eating in some conceivable cases.  But domestication throws a wrench into the works.  Human, predation-via-domestication is a very different thing from predation as it functions in a healthy ecosystem.


Daniel Hooley said...

The sorts of 'goods' you are putting forward, as a defense of the claim that 'predation is a force for good' concern me. Maybe biodiversity is a good (I am honestly not sure). And maybe it is a good thing to have more sophisticated, complex creatures.

But it isn't clear to me why these goods (if they are goods, and if it makes sense to think of them as good) outweigh the harms of suffering and death that predation brings with it. This all seems way too quick, particularly when we use it as a defense for hunting, as you seem to suggest.

Further, the claim that "humans are predators" because we are omnivores is problematic. Humans have been predators, but we can choose not to be. There is nothing essential to being human that suggests we should be predators.

Aeolus said...

Ty Raterman, "An Environmentalist's Lament on Predation"
(available via Google search)
Summary and critique by Ned Hettinger:

My own question: Why is the urge to rape women any different from the urge to hunt rabbits or to hunt the members of that tribe in the next valley and boil the menfolk for dinner? When the strong and the swift win the struggle to survive and reproduce, that makes for a better world, doesn't it?

Jean Kazez said...

Aeolus, Thanks, I'll look at that.

About rape--imagine a world in which nobody every rapes anyone. Instead, people couple based on love and respect. It's not the least bit obvious that a rapeless world is flawed in any way. If you think it is, kindly explain. Without rape, there is still plenty of competition for mates. The "strong and swift" get together, and some people don't get to reproduce. I don't see that rape plays any necessary role in producing good offspring. In fact, rape yields children with mothers who are ambivalent about them and fathers who are absent. So rape just doesn't qualify as a "force for good" in the way predation does.

In short, you can't just plug in your favorite abomination, and say it's a force of good too, if predation is a force of good. You have to actually look at what the true counterfactuals are.

What else is a force for good, but also harmful to individuals? Let's see--how about reproduction? It causes maternal mortality, the pain of childbirth, etc. Reproduction at least in animals involves lots of fighting and aggression (rutting season etc.) Male animals may harass females, etc. So reproduction has lots of negatives for individual animals. Nevertheless-- force for good.

OK, now I'll go to your link.

Deepak Shetty said...

I'm pretty sure the answer is: not as good.
I'm pretty sure we don't have any actual data to support this. No one can predict how things would have evolved if everyone was herbivores. If resources are scarce then the same or similar qualities you find in predators could evolve

Jean Kazez said...

Deepak, Biologists indulge in speculations like this all the time. One example comes to mind--Richard Wrangham's book about the role of cooking in human evolution. He says without cooking, we would have evolved differently--and provides all sorts of arguments to that effect. So there's nothing wrong with the sort of hypothesis I'm throwing out here--"no one can predict" (retrodict?) is way, way too strong. As I say in the post, I'd welcome a biologist's input here. I'd be very surprised if competition over scarce grass and leaves shaped herbivores in exactly the same way that the demands of predation shape predators. The two tasks are too different to select for the same abilities.

Deepak Shetty said...

no one can predict" (retrodict?) is way, way too strong
Ah.. I should have added with any degree of verifiable accuracy.
Its an interesting hypothesis(assuming we agree on 'good') but to classify it as prediction someone would have to have many more experiments. The sheer timescale for such an experiment is why I used no one.