Friday, June 28, 2013

Charles Darwin and the Dominance Meme, Part I

Do Dominance Hierarchies Run Counter to Darwin's Theories?
 Two wolves playing in the snow.


“I aimed for a modest presentation. I would demonstrate simply and directly that male Pumphouse baboons did not have the traditional hierarchy, while females did. … At the end of my presentation, no one spoke. The polite silence was finally broken with barely guarded accusations. I had invented my data. I didn’t have enough information to draw the conclusions I had come to and that there had to be a male dominance hierarchy … I had managed to miss it, that was all.”

—Shirley C. Strum, Almost Human 

Animal Hierarchies Didn’t Exist Before the 1920s.
 The idea that animals form dominance hierarchies is so deeply ingrained into the minds of most scientists today that to say or even hint that things may be otherwise (as Thelma Rowell and Shirley Strum have done) has become something like an act of heresy or sacrilege.1 Animal hierarchies are, in neuroendocrinologist Robert Sapolsky’s words, “textbook social systems, sort of engraved in stone.”

I’ve written a number of posts—both here and at PsychologyToday.com—questioning the validity of dominance hierarchies in dogs and wolves. And I’ve gotten into some hot water for doing so.2 In this post I’ll present new arguments showing:
  1. that the idea of social hierarchies goes counter to Darwin's view of natural selection, 
  2. that there is no evolutionary arc that runs from hierarchical systems in lower animals to those in humans, and
  3. that acting “dominant” may actually reduce an animal’s adaptive fitness.
I realize I’m on a fool’s errand. And I’m more than happy to be taken to task and proved wrong on any of the points I’m going to make here. It just seems to me that dominance hierarchies simply don’t exist in Nature. And it also seems to me that it all starts with a very simple misunderstanding of Darwin’s theory of natural selection.

In Paul Ekman’s 1998 edition of Darwin’s The Expression of the Emotions and Man and Animals, evolutionary psychologist Daniel G. Freedman seems to have criticized Darwin for being unaware of animal hierarchies: “Darwin is aware of submissiveness,” Freedman wrote, “but the naturalistic notion of, say, wolves forming an hierarchical pack is missing. Social hierarchies is a major concept of animal observation today, and many of Darwin’s examples of antithesis would be seen now in terms of hierarchy.” 

True. But is that because Darwin missed the boat or does the idea of dominance hierarchies run counter to Darwin’s theories?

I don’t think Darwin was wrong. I think it’s more likely that the reason he didn’t mention dominance hierarchies is that they didn’t exist during his lifetime. There were no animal hierarchies for him (or anyone else) to observe because, in all probability, they simply didn’t exist until the 1920s when Norwegian biologist Thorleif Schjelderup-Ebbe published his dissertation on pecking orders in chickens.

Scientists began looking for “pecking orders” in all social animals. They sometimes found what they were looking for—though the truth is, sometimes they didn’t. 

Still the concept of pecking orders—which eventually morphed into what we now call dominance hierarchies—caught on like wildfire, or like a meme, an ideological virus that infects the human mind and prevents us from seeing the truth. This meme is so powerful3 that when dedicated scientists like Shirley Strum or Thelma Rowell present data that run counter to this idea, their evidence is ignored, their methods called into question, and the concept of a “latent hierarchy” is invented to account for the lack of hierarchical structure. 

Dominant Species vs. Dominant Behaviors 
I know the idea that social animals form dominance hierarchies seems like pure Darwinism to most. Animals in competition over resources! Yes! But let’s take a look at what Darwin’s theory is really about. 

“The theory of natural selection is grounded on the belief that each new variety, and ultimately each new species, is produced and maintained by having some advantage over those with which it comes into competition.” (Darwin, On the Origin of Species, 371.) 

Here the nature of competition is reserved for different species, not members of the same species, and especially not for members of the same social group. In fact Darwin believed that social animals may be more adaptable because of their ability to work together: “Social animals perform many little services for each other: horses nibble, and cows lick each other, on any spot which itches: monkeys search each other for external parasites. … Animals also render more important services … thus wolves … hunt in packs, and aid each other in attacking their victims.” (The Descent of Man, 71, 72) 

Does it really make sense that members of a social group would be in competition with each other over resources? It seems to me that sociability is about pooling resources, not fighting over them. Finding, isolating, and quantifying these sorts of resource sharing behaviors—now often referred to as “biological altruism”—has become all the rage recently. It’s been shown that even plants share resources with their closest kin. And one of the reasons that scientists are so interested in biological altruism is that it supposedly runs counter to Darwin’s concepts of species being in competition with one another and gaining an advantage over them. 

Perhaps the clearest window into how the dominance meme fails to make sense is the wolf pack—an aggregation of animals whose social structure is built almost entirely around the need to hunt large, dangerous prey by working together as a cohesive social unit. If the prey animal is the pack’s most important resource, and hierarchy formation is about competition over resources, then we should see intense posturing and jockeying for position both during the hunt, and when the pack feasts on its fallen prey. Yet pack members work together, not against one anotherneither dominant nor submissive behaviors are ever seen during the hunt. And once the hunt is over, all members of the pack have mutual access to the carcass of the fallen prey animal, with no hierarchy and very little, if any, dominance visible. 

Plus—and this may be even more important—it’s hard to see how dominance (threats of aggression) would foster group harmony and cooperation. It seems more likely to me that affiliative behaviors—licking each other’s fur, cuddling in the cold, playing with one another, etc.—are the real glue that holds a wolf pack together. 

Leveling Mechanisms in Non-Heirarchical Human Societies 
Another meme is based on what I see as a common misinterpretation of Darwin’s statement that “The difference in mind between man and the higher animals, great as it is, is certainly one of degree and not of kind.” Almost everyone who quotes this trope ignores the fact that a few sentences later Darwin admitted that he could be wrong: “If it be maintained that certain powers, such as self-consciousness, abstraction, etc. are peculiar to man, it may well be … the result of the continued use of a highly-developed language.”

Still, scientists look at the arc of evolution (and thus the arc of hierarchical systems) as reflecting this shaky theoretical difference of degree and not of kind. This may be one reason we can’t help but see dominance hierarchies in apes, wolves, crayfish, and guppies, etc. 3 

But is there really an evolutionary arc that runs from lower animals to human beings?

Primatologist Shirley C. Strum writes, “Many of the models of human evolution have assumed that the human experiment began with limited social resources, instinctive and compulsory aggression, male domination and rigid hierarchy. But these models seem faulty if we now know that ‘lowly’ baboons are more complex and have more diverse options. Were the earliest humans not as smart or skillful as baboons?”

And we don’t even have to look at baboons. Scattered in various pockets of the globe are small bands of indigenous hunter/gatherer societies who not only don’t form dominance hierarchies, they’ve developed leveling mechanisms to prevent them from forming. And one of the primary reasons they do so is because—just as it would in a wolf pack— hierarchical systems lessen the group’s ability to hunt successfully.

Another leveling mechanism in these egalitarian societies relates back to wolf behavior as well, and  that’s play, an activity that wolves—and especially dogs—engage in on a regular basis. (Now there’s a set of behaviors that actually do have an evolutionary arc…).  

Acting “Dominant” Decreases an Animal’s Adaptive Fitness 
It’s said that the dominant member of the group is the one most likely to pass on his genes to the next generation, and that’s the fundamental purpose of hierarchies: to provide the most robust animal a non-negotiable platform for reproduction. But if the true purpose of a wolf’s social instincts is to enable the pack to work together to hunt large, dangerous prey, how do internecine battles over bones and sleeping places relate to their overall adaptive fitness? In wild packs it’s normally rare for any but the breeding male and female to pass on their genetic material to future generations. Would one night’s sleep on a less-than-perfect “bed” or taking a bone away from another wolf really tip the scale toward genetic oblivion, and that’s why wolves supposedly have to exert their “dominance” over such things?

Is it even true that the most dominant male in a wolf pack—or any social animal group—is automatically more able to pass on his genes to the next generation?

Apparently not. In his studies of baboons Robert Sapolsky found that dominant behaviors actually have a negative impact on survival.4 

At one point, a troop Sapolsky had been studying for years, and who exhibited the classic male hierarchical structure, came across a human garbage site. Yay! Free food! But the food was unfortunately tainted with tuberculosis. The troop was decimated.

Yet interestingly, it was the most “dominant” baboons who lost their lives, not the other way around. The reason? Dominance isnt a normal or natural behavior. Its always triggered by stress. And high levels of the stress hormone cortisol tend to suppress an animal’s immune system. (Excessive levels of testosterone don’t help matters any, either.) And that's why the most dominant baboons in the troop died.

“It wasn’t random,” says Sapolsky. “If you were aggressive, and if you were not particularly socially connected, socially affiliative, if you didn’t spend your time grooming and hanging out—if you were that kind of male—you died.” 

A generation later, Sapolsky came back to find that the troop had been transformed. They were much more amenable, social, and affiliative now. There was no longer a clear hierarchical structure (as Rowell and Strum had seen in their studies of baboons). And if you were an “alpha type,” trying to dominate others, you were quickly shunned!

Sapolsky says, “One of the things that baboons teach us is that if they’re able to, in one generation, transform what are supposed to be textbook social systems, sort of engraved in stone, we don’t have an excuse when we say there’s a certain inevitability about human social systems.”

Another thing that the baboons teach us is that hierarchy formation in animals does not serve an adaptive purpose. Just the opposite.  And, in the end, these social structures only exist in our own minds because that’s how we see the world.

Some would argue that hierarchies do, in fact, exist. They’ve been observed. Data has been collected and analyzed. And while there may be gaps in logic here and there, it’s simply undeniable that animal hierarchies exist.

I agree. They do exist, but they’re not normal or natural; they’re stress-related behaviors, brought on by the simple act of being observed by human beings. In fact—and I’ll develop this idea further in my next post on this topic—these behaviors are more likely to be produced when animals are being observed by male rather than female scientists. 

LCK 
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Footnotes: 

1) “I was na├»ve. I had imagined that one did the research, gathered the information, analyzed, interpreted and presented it to the scientific world. Then the work would be evaluated and incorporated, if accepted, into the basic knowledge within the field. But there are cliques in science as in any other facet of human endeavor. If you are part of the ‘in’ group, even minor findings are discussed and integrated, eventually becoming part of the working knowledge of the field. If you are not part of the clique, you stand a good chance of being ignored.” 
 —Shirley C. Strum, Almost Human


2) Every time I posted a mea culpa at PsychToday, it was because other authors at the site complained to my editor. This happened most often when I wrote about the myth of dominance hierarchies, proving that dominance hierarchies do exist, just in scientific circles not animal groups. (I’m not saying this to compare myself to Shirley Strum, Thelma Rowell, or others who’ve fought the orthodoxy, but to point out how strongly those in the scientific community feel about the subject.)


3) “Our findings show for the first time that individual differences in the preference for social dominance hierarchy predict neural response within left AI [anterior insula] and ACCs [anterior cingulate cortices].” (“Neural Basis of Preference for Human Social Hierarchy versusEgalitarianism,” Joan Y. Chiao et al.

4) Please watch this wonderful video to see and hear Sapolsky describe, in his own words, how the baboon troop changed from a pro-dominance to pro-affiliative society. 

Wednesday, June 26, 2013

Dance With Me, I Want to Be Your Partner

Increasing Your Dog’s Social Attraction

One of the most important training innovations that Kevin Behan brought in his book Natural Dog Training, was the idea that dogs experience the world through feelings of attraction and resistance, almost as if each dog were a charged particle or one of Newton’s moving bodies, being influenced by invisible forces rather than engaging the world through the principles of dominance and submission or via associative learning.

Dogs don’t pull on the leash as much as they’re pulled on by things
in the environment that exert a kind of emotional gravity on them.

There are numerous ways to increase a dog’s social attraction to its handler, meaning that the vigor behind the dog’s usual interest in squirrels, interesting smells, other dog’s hineys, etc., is transferred onto the person at the other end of the leash—meaning you. One cool way of doing that is through what I call the “Dance With Me” exercise.

Start by teaching your dog to jump up on command (click here for details), then teach him to only jump up when the command is given, then teach him that he has to stay up until you give him the release signal, “Okay, off!” (This is also a cool way to curb your dog’s tendency to jump up whenever he feels like it.)

Once your dog has those skills under his belt you can start doing the “Dance With Me.”

It’s best if you take your dog to a safe, open area where there’s plenty of room to run around, and with few distractions. 

Let your dog’s attention wander away from you momentarily. This shows that she’s looking for something to plug her energy “in to.” Without actually giving a recall signal (i.e., calling her to come to you), let her know with a whistle or a kissing sound that you want her to pay attention. When she references you, show her a treat or a toy. (Treats work best when first starting to do this exercise.)

If she comes to you on her own, fine. If not, you may have to start moving away from to increase her attraction to you. Then, as she comes right up to you, invite her to jump up, using the command, “Okay, up!” Then release her, saying, “Okay, off!” in a happy voice. 

Repeat this sequence.

Ask her to jump up a third time, but once she makes contact with her front paws, place the treat directly under her nose but don’t let her take it. Instead, start back-pedaling while praising her enthusiastically. Keep the treat right under her nose, praising her while moving backwards for about 5 feet or so. Then give her the treat and praise her extravagantly. Do this twice more, then go back to what you (and she) were doing before. (If you have a very large dog, you can place one arm across your chest—as if you’re a Roman soldier, holding a shield—and have the pooch put his paws there.

You can do this exercise any number of times during your walks or training sessions. But I would recommend doing it only 3 times in a row, then taking a break for play or for whatever other activities you and she want to engage in.

The following day (and on the days after that) you’ll want to start making things a little harder by slowly increasing the distance she has to stay up while you backpedal, going from the original 5 feet to 10 feet, then to 15, then 20, to 25, and finally to about 50 feet.

Some dogs will have more of an ability to sustain their “drive to connect” for longer periods or over longer distances than others. So always “reward” the dog with the treat and lots of praise before her drive subsides. If she has trouble staying up as long as she’d been doing the day before, go back a little by decreasing the distance. If on a certain day your dog doesn’t seem as motivated to do the “dance with me” as before, play a game of “chase me” with her first.

If your dog likes to play tug-of-war, another cool variation is to ask her to jump to grab the toy, then backpedal while she tugs on the rope toy or a bandana with knots in either end.

This exercise should accomplish 2 important goals: 1) it will make your dog much more likely to come when called (and she’ll come running with much more vigor than before), and 2) it will help increase her tendency to “stay in the pocket” while walking next to you on the leash, or even off-lead, for that matter. 

In fact, you can incorporate the “Dance With Me” game into both commands. For example, if your dog has wandered off, and you want her to come running back to you, get her attention then, when she looks at you, pat your chest or thigh, as if you want her to come play “Dance With Me.” She’ll probably come running faster than usual.

You can also incorporate heeling into the “Dance With Me” game. As you’re moving backwards, and it’s time to allow the dog to jump down, don’t reward her yet with the treat or the toy, but twist sideways so that she’s next to you in the heel position, and keep her moving in synch next to you, saying, “Heel!” in a happy voice, luring her with the treat or toy. Then give her the treat or throw the ball for her to chase.

I should mention an important caveat. It's not advisable to do this exercise with nervous dogs. Those who have a withdrawn nature won’t enjoy being asked to jump up. They might do it, but they won’t enjoy it. Meanwhile, dogs who have the kind of nervousness that’s more extroverted may have too much enthusiasm; they may not only jump up on you, they may grab your arm or rip your clothing, try to start humping you, or even knock you over. 

You should spend time with both kinds of dogs working on resolving some of their nervousness (via “The Pushing Exercise” and “The Eyes”) before getting them to play “Dance With Me.”

Sunday, June 16, 2013

How Do You Stop Your Dog From Humping?

Is Humping a Sign of Dominance or a Symptom of Frustration?

Originally published in slightly different form at PsychologyToday.com on July 22, 2011.

In his most recent article here, Dr. Stanley Coren, a highly esteemed scientist and well-known expert on dogs, gives us his view of why dogs hump. He says the behavior has nothing to do with sex; it's all about showing dominance. 

Since dogs don't just mount humans and other dogs, but will also hump their toys, pillows, and blanketseven a family cat or rabbitit seems very unlikely that this behavior is about social dominance.

So what is this behavior really about?

I think it's about a blocked feeling of attraction. The dog feels an attraction to a person, animal, or object, but for some reason is unable to express it in a normal way, i.e.., through mouthing, biting, or playing. When the frustration reaches a certain level, the humping begins.

Mounting another dog from behind is a behavior often seen when dogs play (see Bekoff and Byers 1981 and Fagen 1981). And it seems to happen most often when one dog is frustrated that he can't get another dog to play with him. In such cases, the first dog may start humping his potential play partner just to instigate a round of "chase me."

For anyone with the propensity to see dominance where none exists, this could be interpreted as an intention to dominate the other dog by forcing it to play. Yet I've seen numerous dogs, who seemed desperate to get a non-compliant partner to play with them, who've tried humping that dog, gave up, tried again, then rolled over on their backs in a "submissive" posture. The only constant was not the first dog's alpha status or his dominant personality (otherwise why would these dogs have started acting submissive?); it was simply that the dogs had a strong desire to play with the other dog, and the energy behind that desire had nowhere to go.

Dr. Coren rightly says that the tendency to hump another dog is seen in a litter of puppies[1], though he reports this fact to reinforce the idea that humping is not a sexual behavior, because a puppy's sexual development is several months away. But development of the pup's hunting skillsthe chase, the eye-stalk, the grab-bite, the kill-bite (shaking the head around while holding a prey object in the mouth)is also several months away. Yet they're clearly seen in puppy play too.

Let's say, for a moment, that dominance, as a behavioral tendency, does exist in puppies. One of the theoretical hallmarks of having higher status is maintaining control of resources. In what way does humping get the supposed dominant pup a better feeding or sleeping spot, or better access to anything good? If dominance does exist, it would be in relation to pushing another puppy out of the way of mother's milk, etc., not mounting him or her from behind.

Dr. Coren also notes that humping is about showing leadership toward one's littermates. But in what way, and in what possible context, does humping show leadership?

A simpler explanation is that the behavior is caused by a frustration of the dogs desire to connect (or cathect) to an object of attraction.

Of course it can't just be about feeling frustrated because another dog won't play. That might explain what happens in the dog park, but not why a dog humps the mailman's leg, or why he humps his own toys or blankie, or why he tries to hump visitors.

Like most aspects of canine behavior, I think this behavior comes from the way canines have had to sublimate their urge to bite, going back to the formation of the first wolf pack, millions of years ago.

It's unusual for predators to form social groups because without something to damper their natural aggression odds are they might begin attacking one another. This is the primary reason most predator species don't live together in close-knit groups. But in order for wolves to successfully hunt large prey, they need to form packs. And in order for the pack to be stable, wolves have to exert impulse control over their urge to bite each other.

Once humans started domesticating dogs, those animals who exerted the most impulse control over their urge to bite were the most successful at living long enough to pass on their genes to the next generation. And this tendency slowly became encoded into a dog's DNA.

And I believe that this ability to sublimate the urge to bitepartially genetic, partially conditioned in the litteris the primary mechanism behind all canine social behavior.

It's not about domination, it's about sublimation.

There's a broader way of looking at this. Sodium and chlorine atoms have an interesting structure that enables them to connect to one another, creating sodium chloride (salt): NaCl. The same goes for hydrogen and oxygen: H2O. A plant sends its roots down to the soil seeking nutrients, its leaves up to catch the sun's rays. Jellyfish, who have no nervous system, are still somehow able to seek out and kill their prey. Without a mechanism for each aspect of natureatoms, molecules, jellyfish, wolf packs—to be able to make connections to other parts of the natural world, there would be no natural world. Everything has to connect to something else for it all to work. [2]

Wolves are designed to connect to their prey through their teeth and jaws. Puppies show an urge to connect to almost everything they encounter through their teeth and jaws. This is an incredibly strong urge that takes place during a very specific window of time. And when that urge is stifled or repressed by the pup's owners, it can wreak havoc on the pup's ability to form normal social relationships with people and with other dogs.

The urge to bite is still a strong one, and it has to be given some kind of outlet or else neurotic behaviors of one kind or another will surface. This is as predictable as the fact that water runs downstream.

In his article, Dr. Coren says that humping should not be permitted. It should be stopped to maintain the pack hierarchy.

It's true that humping should not be allowed, encouraged, or tolerated, at least not for very long. But if the urge to hump comes not from the urge to dominate, but from unresolved issues that took place during a puppy's oral development phase, then what is the best way to prevent a dog from engaging in this disagreeable behavior? To dominate him? I don't think so. Just give the dog a safe means of satisfying his urge to bite/connect. This may sound strange to some, but it's absolutely true. And it can be verified quite easily.

Several years ago I got a call from a family who'd just adopted a rescue puppy named Tippy, who was about 7 months old, and they were having behavioral problems with him.

Tippy greeted me at the door, in a fairly normal waymaking friendly eye contact and jumping up to say hello. We went into the kitchen and sat down at the table to discuss what was going on, and Tippy began panting and pacing the floor, occasionally coming over to mount my leg for brief spurts. I ignored him, using the theory that a behavior that isn't being reinforced will eventually extinguish itself. However, this theory had no effect on Tippy's behavior. 

I talked with the family for about thirty minutes and yet the dog still hadn't stopped pacing the floor, panting, and coming over occasionally to mount my leg.

I finally realized that Tippy needed my help to calm down. So the next time he came over, but before he could start mounting my lgeg, I scratched his cheek with one hand, and put two fingers of the other into his mouth, encouraging him to nibble on them. He bit down very gently and I softly praised him for doing so, petting him the whole time. After a while he got tired of chewing on my hand and went under the table to lie down and almost immediately fell asleep, calm at last.

As I walked home I thought about Tippy's reasons for humping me. He seemed more frustrated than dominant. But why was he frustrated?

It struck me that Tippy, like all dogs, had a strong desire to make social contacta strong desire to connectbut had to do so in a way that would also satisfy his urge to bite (i.e., by bringing me a toy). But the normal social development of this pup had, in all likelihood, been repressed by his previous owners during his oral development phase. (Remember, puppies are designed by Nature to connect to their environment primarily through their teeth and jaws.)

This why, after I let Tippy chew on my fingers for about 30 seconds, he finally stopped humping my leg, calmed down, and went to sleep. The act of mouthing me satisfied his need to connect orally. Once that need had been satisfied, the humping behavior disappeared.

I see only one possible explanation for what happened. I said earlier that my hypothesis about the underlying cause of a dog's humping behavior is easily verifiable, and it is: if a dog has a humping problem, and you give him an outlet for his urge to biteideally through playing tug-of-war, letting him win, and praising him for winning (preferably outdoors)the need to hump should go away, as if on its own.

What I think is most interesting about this story is that I successfully controlled the dog's behavior (that is, I "dominated" him) by simply allowing him to chew on my fingers for about 30 seconds.

And he never tried to hump me again. 


Footnotes: 

1) One might be tempted to think of a litter of puppies as being essentially like a pack, except for the fact that, as Ray Coppinger says, pack formation in canids is a function of prey size. Dogs don't hunt large prey; they get their food in a bowl. So they don't form packs. Even feralized domestic dogs don't hunt large prey, so even they don't form packs. Puppies obviously don't hunt large prey, and they certainly do not form packs. And without a pack there can be no pack hierarchy.

2) Sigmund Freud hypothesized that this need to connect eventually evolved into the sex drive. "Even though it is certain that sexuality and the distinction between the sexes did not exist before life began, the possibility remains that the instincts which were later to described as sexual may have been in operation from the very first." ("Beyond the Pleasure Principle," The Freud Reader, p. 615). 

If this is true then Dr. Coren may be off-base when he says that humping is not a sexual behaivor. It could very well be a displacement of normal sexual energy

Saturday, June 15, 2013

Lack of Cooperation Found in Some Wolf Packs

Why Does Cooperation Diminish as Pack Size Increases?
Originally published in slightly different form on Nov. 9, 2012 at PsychologyToday.com.  
 Should the Principles of Economics be Applied to Wolf Packs?
One area of great interest in current biology is animal altruism and cooperation. These qualities are said to exist at all levels of life, from aggregations of cells to human society.

In their paper, “The evolution of cooperation and altruism,” (2006) Lehmann & Keller write, “One of the enduring puzzles in biology and the social sciences is the origin and persistence of intraspecific cooperation and altruism in humans and other species.”

Because cooperation and altruism in non-human animals really is so puzzling animal researchers rely on disciplines like experimental economics and game theory—designed to explain cooperation in human society—and apply them to non-human animals.

Wolves are often cited as a prime example of cooperation in social animals. Yet research shows that hunting success peaks at about ± 4 wolves. The larger a pack gets, the less successful they are.[1]

Why is this so?

In a 2011 article, McNulty, Smith, Mech, et al say that there are 2 prevailing hypotheses for why group-specific hunting success (Hn) declines in larger packs. The interference hypothesis proposes that Hn is limited because individual predators impede each other’s actions. The other possibility is the “free-rider” hypothesis, a term borrowed from economics, where “free riders” are defined as those who consume more than their fair share of a resource, or shoulder less than a fair share of the costs of its production. (Economics is what gave us the mistaken idea that dogs know when they’re being treated unfairly: see here, and here.)

Defining Pack Hunting Behaviors 
The wolf researchers measured levels of participation by pack members during various stages of the hunt, using an ethogram (an objective scientific inventory of a set of behaviors) developed a few years earlier by McNulty, Mech & Smith (2007).

Behavior:
Definition:
Search
Traveling without fixating on and moving toward prey.
Approach
Fixating on and traveling toward prey.
Watch
Fixating on prey while not traveling.
Attack-group
Running after a fleeing group or lunging at a standing group while glancing about at different group members (i.e., scanning).
Attack Individual
Running after or lunging at a solitary individual or a single member of a group while ignoring all other group members.
Capture
Biting and restraining prey.

The idea that hunting success was negatively impacted because wolves in packs with >4 members withheld effort was generally borne out by the fact that the rate of decline was most apparent for the most dangerous task above: capture, or biting and restraining prey. In other words, as pack size increased fewer wolves felt like going in for the kill.

McNulty et al conclude: “Our study suggests that [some] wolves in large groups (>4 hunters) withheld effort … and likely participated merely to be at hand when a kill was made.” [Italics mine.]

Personally, I think that’s very unlikely. Don’t get me wrong; this is a dedicated group of scientists who are at the top of their field. They’ve done a wonderful job of compiling research and applying the principles of group cooperation as put forth in previous animal studies based on economic theory, etc. But while their conclusion is right and proper within that specific context it still requires the wolves to engage in some very high-level, humanlike thought processes.

Morgan’s Canon & Information Theory 
Morgan’s canon states that, “In no case is an animal activity to be interpreted in terms of higher psychological processes if it can be fairly interpreted in terms of processes which stand lower in the scale of psychology and evolution.”

Yet these are the thought processes a wolf would have to engage in for the reasons given above: “I’ll withhold my own efforts (requiring a sense of self) knowing that the other wolves (requiring a sense of self-and-other) will probably do all the work for me (requiring hypothetical thinking) so that later on (requiring mental time travel), when the elk has been killed (requiring an ability to project hypothetical thoughts onto hypothetical future events via mental time travel), I’ll be able to eat my fill anyway (more mental time travel, more hypothetical thinking).”

None of these forms of cognition have been found to exist in canids.

McNulty et all would probably counter by saying they’ve drawn no such conclusions. They’re only presenting the data, using a widely accepted scientific model.

This is true. The problem isn’t with their research, which is impeccable. As I see it, the problem is with the model. A wolf pack is not an economic system. There are no goods and services being sold or bartered, no markets or distribution points, no currency changing hands. (There are some similarities of course, but not enough, in my opinion, to make total sense when applied to most non-human animals.) But while there's no currency exchange there is an exchange of information. So I think applying information theory would give us a more parsimonious explanation as to why "cooperation" in wolves decreases as pack size increases.

More Wolves = More Noise?
In the ethogram developed by McNulty, Mech & Smith, pack hunting behaviors are described in the most objective of terms. There isn’t the slightest hint or suggestion as to why the animals are exhibiting any of these behaviors. Can lack of success in larger packs also be explained without attaching humanlike reasons for behaviors?

Yes, but in order to do so we have to look at the hunting process through the wolf’s eyes. That doesn’t necessarily mean we’re pretending to know that the wolf’s experience is. We’re just making objective observations about where the wolf’s attention is focused.

When a single wolf hunts small prey on his own he only has to focus on 2 primary external stimuli: 1) the prey’s movements and 2) the terrain both animals are moving through. When the same wolf is hunting with his pack mates, he has another set of stimuli to focus on (at least peripherally), 3) the movements of his confederates.

In wolf packs of optimal size (± 4 members), each wolf is processing information via ± 4 sets of signals: ± 3 sets coming from his fellow pack mates and 1 set coming from the prey animal. As the number of wolves increases, so does the number of signals each individual wolf has to process. As the number of signals increases the potential for “noise” in the system increases as well.

McNulty et al write, “Several lines of evidence suggest that decreasing individual performance resulted from declining effort in response to high hunting costs.” That may be true, but I would suggest that decreasing individual performance resulted from a decreasing ability to differentiate between information and noise.

Is it that simple?

Yes and no. For instance, while all members of a large pack were less likely to engage in the attack and kill behavior, breeding wolves still engaged in those behaviors more often than non-breeders did.

Carrying Capacity and Dunbar's Number
 This could be explained through a kind of anti-green beard effect where the individual wolf's genes were running the show. Or it could be explained through differences in channel capacity (or carrying capacity); the operating thesis being that in most cases, breeding wolves are also the so-called “pack leaders,” and as such have to routinely pay attention to more sets of signals than their subordinates do. So whether through experience, or genetics, or both, breeding wolves would hypothetically be more capable of receiving multiple streams of information at once without experiencing them as noise. Since the final act of the hunt is the most dangerous, it also requires the most intense focus. Non-breeders would be less able to tune out system noise, which would hypothetically be what's actually inhibiting them from going in for the kill or actively participating in other aspects of the hunt.

Finally, a simple conjecture: British anthropologist Robin Dunbar has suggested that for human beings there’s a limited number of people with whom one can maintain stable social relationships and that “this limit is a direct function of relative neocortex size.”

My conjecture is that there may be a kind of Dunbar’s number for pack size as well. After all if hunting success decreases in inverse proportion to any pack of >4 wolves, it may well be because there's a limited number of wolves with whom each wolf can maintain a stable relationship. This wouldn't require some wolves to withhold their efforts or pretend to participate in order to get a free meal.

I'll leave it to you to decide which model makes more sense.

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Footnotes:
1) Computer models show that wolves don't need to form the intent to cooperate while hunting, which suggests, by contrast, that they probably don't withhold their efforts (or fail to cooperate) either.