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 
“Changing the World, One Dog at a Time”
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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. 

2 comments:

Anonymous said...

Packs or herds will care for the old, sick, or weak, up to a point. After that the straggler is likely to get mauled by other predators or packs. So the open question is why do certain members of a pack get thrown out?
Could it be from unsuccessfully trying to upset the dominance hierarchy.

LCK said...

No. There is no dominance hierarchy.

Pack dispersal ("throwing out" certain members of the pack) typically happens when a) when the offspring are old enough to form their own packs or b) when the pack becomes too big too sustain itself successfully.

There are numerous other factors that determine this process but "trying to upset the dominance hierarchy" can't be one of them because hierarchies don't exist except in the human mind.