Field of Science

The Origins of Inequality
Inequality is a national conversation topic now, thanks largely to the efforts of Occupy Wall Street and the broader Occupy movement. Fundamental questions are being asked, such as "Must inequality necessarily be a part of human society?", "Are we genetically disposed toward hierarchy or egalitarianism?", and "What would a global egalitarian human society look like?"

We can gain a bit of perspective on these questions by looking at the evolutionary history of humans and our primate relatives:
  • Our two closest animal relatives are chimpanzees and bonobos. Chimpanzee society is characterized by a strict hierarchy of males, with frequent aggressive conflicts between them to maintain or challenge dominance order. In bonobo society, on the other hand, hierarchies are weak, and conflict resolution is peaceful, often involving sex play.
  • Baboon societies in the wild are also characterized by a strict dominance hierarchy, in which higher-ranking males regularly harass lower-ranking ones and commandeer their food or resting spots. There is one notable exception, however. In 1982, all of the dominant males in a baboon tribe observed by Robert Saplosky were suddenly wiped out by a tuberculosis outbreak, leaving only the lower-ranking males. There followed a marked shift in the culture of the troop: hierarchy remained, but those at the top were much less likely to harass lower-ranking males or steal their food. Moreover, this more relaxed culture was observed in the same tribe two decades later, even after all the males present during the original shift had died or migrated to other tribes (Saplosky and Share 2004).
  • Modern hunter-gatherer societies, the closest analogue we know of to our distant ancestors, are uniformly characterized by a strong egalitarian ethos, in which resources are shared and those who attempt to hoard them are ostracized (Boehm 2001). On the other hand, the transition to agriculture lead to the advent of unequal social classes, with the lower classes often suffering from malnutrition (Diamond 1987).

From left to right: Chimpanzee, Bonobo, Olive Baboon.  Source: Primate Info Net

Taken together, these examples suggest that humans aren't inevitably predisposed to either hierarchy or egalitarianism. Rather, we are capable of either mode of society. These examples also suggest that, like the baboons, we might be able to shift from one mode to the other in the wake of a destabilizing catastrophe.

A mathematician, economist, or theoretical biologist would call this an example of multiple equilibria. The situation might be depicted like this:

That is, there are two stable configurations of society (really, much more than two, but we're simplifying here): hierarchical and egalitarian. Each equilibrium is stabilized by different mechanisms. In hierarchical societies, those at the top have enough power to squelch any attempt at overthrowing the hierarchy. In egalitarian societies, those who attempt to selfishly amass resources or power are ostracized by the rest of the group. Christopher Boehm discovered these mechanisms for egalitarianim in his survey of modern hunter-gatherer societies
I discovered that their egalitarian political arrangements were quite deliberate. They believed devoutly in maintaining political parity among adults. This belief was so strong that males who turned into selfish bullies, or even tried to boss others around for reasons useful to the group, were treated brutally, as moral deviants. (Boehm 2007)
Because of these mechanisms, the two extreme ends of this spectrum are quite stable. Escaping them is very difficult without a demographic catastrophe like the tuberculosis outbreak in baboons, a major technological shift like the development of agriculture, or a "starting over" opportunity like the colonization of a new continent.

The middle regions of this spectrum, however, are less stable. In these regions, some individuals wield a disproportionate share of power, but not enough to completely suppress the interests of the less-powered classes (the 99%). This leads to persistent power struggles between these classes, in which the balance could ultimately be tipped in either direction.

The United States has always been an unequal society, but the checks and balances of democracy have thus far kept it from sliding into despotic hierarchy. The balance of power has fluctuated throughout our history, with periods of robber baron-style capitalism alternating with progressivist movements. I'm worried, however, that we're currently sliding toward self-reinforcing inequality, as the moneyed elite increase their influence over politics, which leads to policies that make them richer, which gives them even greater influence over politics, and so on.

This multiple equilibria model tells us that we may have only a limited window of opportunity to correct this slide. If an equilibrium of extreme inequality is reached, only an enormous catastrophe would be able to undo it.

Sapolsky, R. and Share, L. (2004). A Pacific Culture among Wild Baboons: Its Emergence and Transmission PLoS Biology, 2 (4) DOI: 10.1371/journal.pbio.0020106

Demographic Transitions and the Future of Humanity

This week, the field of science bloggers are addressing the question "Are we doomed?"  It's a good question.  There is no shortage of evidence that we are, in fact, doomed.  But as an incorrigible optimist, my response is a cautious "maybe not?"

What am I referring to here?  In talking to friends concerned about the future of the world, many express a fear that the human population and its economies will continue to grow until they can no longer be sustained by the resources available on the planet.  At this point there will be a great "crunch", as billions die and the rest endure a life of scarcity and strife.  This fear is not new; it dates back to Thomas Robert Malthus, who wrote in his 1798 "Essay on the Principle of Population" that

The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction, and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.

So the Maltusian prediction is yes, we are doomed. But according to contemporary demographic forecasters, Malthus was, surprisingly, wrong. The human population is not growing without bound. Rather, the growth rate is slowing, so that the total population level is headed for a peak—and relatively soon! A 2001 study entitled "The End of World Population Growth" put the chances at 85% that the human population will peak before 2100.  Here's a graph of their projections, with the most likely outcomes shaded darkest:

The numbers on the right-hand side are probabilities of being less than some number.  For example, there is an estimated 14.4% chance that the population will be less than 6 billion in 2100, and an 89.4% chance it will be less than 12 billion.  The thick white line is a UN prediction, not part of this study, provided for the sake of comparison.

This turnaround is remarkable, since the human population has been growing exponentially, with few declines, since the beginnings of recorded history.  So what's behind this unprecedented reversal?

It turns out that Malthus didn't know everything about human nature.  Population scientists have noticed a surprising, yet robust, pattern in human societies, which they call the "demographic transition".  This transition occurs in stages, which are linked to economic and social development.
  1. In pre-industrial societies, parents have many children, since the survival of each individual child is uncertain.
  2. As improvements are made to food supply, hygiene, health care, and infrastructure, more children survive. This leads to a period of rapid population growth.
  3. As the society becomes increasingly urbanized, children become less of an asset (for helping with farmwork) and more of an expense (they must be educated in order to participate in the economy). Increasing education also gives women options other than motherhood. Access to and acceptance of contraception increases. As a net result, birth rates fall.
  4. Eventually, birth rates decrease to levels comparable to or even less than the death rate. The population level then stabilizes or even contracts.
This transition can be seen clearly in the birth and death rates of Sweden:

Lines indicate number of births (blue) and deaths (red) per 1000 people per year.

Note that the death rate in Sweden now exceeds the birth rate.  This is also true of most European nations, as well as Canada, Russia, Iran, Japan, China, and many other countries.  The United States is an exception for now—but the New England states are an exception to the exception!   Many more developing countries have declining birth rates, so that their populations are predicted to stabilize within decades. 

The idea of the demographic transition, and its robustness across human societies, gives me hope.  Not only because it predicts the end of population growth, but also because it suggests a new paradigm of human existence.  A paradigm where quality of life is valued over quantity of life.  A paradigm where each individual is cared for, educated, and allowed to dictate the course of his or her own life.  A paradigm where the population is stabilized not by coercion, disease, wars or famine (as Malthus predicted) but by the free choices of happy and healthy people.

Of course, there are still major obstacles to overcome before we can live sustainably on this planet.  Even as our population stabilizes, irreparable damage to our environment continues.  Global consensus remains elusive on challenges such as climate change, deforestation, and biodiversity loss.  And conflict, inequality, and oppression squander much of our global human potential.

But the existence of the demographic transition suggests a goal for humanity: 

We must facilitate and manage the demographic transition across human societies, in an environmentally sustainable way.

If we achieve this goal, we will be on our way toward a healthy and happy, indefinitely sustainable human population.  So maybe, just maybe, we are not, in fact, doomed.


Freedom and the Public Goods

Last post, I used the example of a protest against peanut allergy-related procedures to explore how the American conception of "rights" may be changing. In particular, I suggested that ideas of common or collective good were being displaced by an increasingly narrow and selfish definition of individual liberty.

A few friends pointed out that I may have unfairly maligned libertarians, anarchists, and others wary of government power.  These people aren't necessarily opposed to volunteerism or helping others; they just don't want to be coerced into doing so (or have their money taken for these purposes).  

This is a fair point.  However, it doesn't make me feel much better about the "leave me alone" political philosophy.  I don't think this philosophy will ever be up to solving our common challenges.  To illustrate why, I'd like to bring in a concept from game theory.

The Public Goods Game represents situations in which there is a common resource ("public good") that benefits all members of a group.  The public good might be a clean kitchen, a functioning electrical grid, or a healthy environment.  This good cannot be maintained without contributions from some group members.  Contributions can be in the form of doing something (washing dishes, working in the community garden, donating to NPR) or not doing something (not littering in a public park, not overfishing a lake).

The dilemma is this: everyone benefits from the public good, but contributions are voluntary.  The public goods game has no built-in incentive to contribute, beyond the desire to make things better for everyone.  So "free-riders" can benefit from others' contributions without contributing anything themselves. 

Both theory and experiment predict that cooperation cannot be sustained in such a game.  A typical experimental result looks like this:

Horizontal axis is time (number of game rounds)  SOURCE: Fehr and Gaechter (2000)

Contributions decline over time to virtually nothing. This is not because the participants are inherently selfish.  Indeed, at the start of the game, many people are inclined to contribute.  However, they realize at some point that others are exploiting their generosity.  Not wanting the benefits of their hard work to reward those who don't contribute, people eventually stop contributing altogether.  This unfortunate outcome has a name: the Tragedy of the Commons

Economists and social scientists have identified a few mechanisms that can reverse this tragedy.  If the participants know each other, and also interact in settings aside from the game, then concern for one's reputation can motivate people to contribute (Milinski et al. 2002, Rand et al. 2009).  This helps explain why co-ops can be successful: everyone knows each other.  They can reward or punish others based on their contributions to cooking, cleaning, and other tasks. 

But what about global challenges like climate change, environmental conservation, and sustainable use of resources?  These involve billions of players across the globe, and there are strong financial incentives to exploit the public good for individual gain.  Furthermore, it can be difficult to trace problems like pollution or overfishing to the individuals or companies responsible.  How these large-scale challenges be solved?

Research has identified only one answer. If the game is too large and complex for individual interactions to maintain cooperation, the solution is for the participants to invest in institutions (Gureck et al., 2006; Sigmund et al., 2010).  These institutions must have the power to investigate the actions of individuals, and reward or punish them based on their contributions. In other words, a social contract is needed, together with institutions to enforce it.

Of course, powerful institutions have inherent potential for corruption and abuse.  This is what worries libertarians and anarchists.  I share that concern.  But the solution, in my view, is to build in democratic checks, so that these institutions are as responsive as possible to the people they serve.

It's hardly a perfect solution.  Institutions can become entangled with those they should regulate.  Democratic checks can be co-opted. 

But to solve the largest problems that face humanity, we can't count on good will and personal responsibility alone.


Ernst Fehr, & Simon Gaechter (2000). Cooperation and Punishment in Public Goods Experiments American Economic Review, 90 (4)

Özgür Gürerk, Bernd Irlenbusch, & Bettina Rockenbach (2006). The Competitive Advantage of Sanctioning Institutions Science, 312 (5770), 108-111 DOI: 10.1126/science.1123633

Milinski, M., Semmann, D., & Krambeck, H. (2002). Reputation helps solve the ‘tragedy of the commons’ Nature, 415 (6870), 424-426 DOI: 10.1038/415424a

Rand, D., Dreber, A., Ellingsen, T., Fudenberg, D., & Nowak, M. (2009). Positive Interactions Promote Public Cooperation Science, 325 (5945), 1272-1275 DOI: 10.1126/science.1177418

Sigmund, K., De Silva, H., Traulsen, A., & Hauert, C. (2010). Social learning promotes institutions for governing the commons Nature, 466 (7308), 861-863 DOI: 10.1038/nature09203

Peanut Allergies and the Future of Democracy

Parents are picketing a school in Edgewater, Florida because of restrictions the school put in place to protect a child with a peanut allergy (thanks to my sister for alerting me):

To summarize: a number of parents apparently feel that common-sense measures such as regular hand-washing (which the school is legally required to enforce by the Americans with Disabilities Act) are too onerous to bear. They are demanding that instead this child be removed from the school.

What's going on here? First of all, the claim that these procedures are taking away from educational time is ridiculous. A child with even a moderate behavior problem will waste far more instructional time than these hand-washing procedures ever could. But disruptive students aren't targeted for picketing by parents. Then there's the distraction created by the protesters themselves, which I'm sure is seeping into the classroom.

So it's not about educational time. What is it about then? I can't read these parents' minds, but there are disturbing clues in the language that some of them are using. "They're trying to take away all our rights," says one parent, while a sign reads:

To which rights are they referring, exactly? The Right of Sullied Hands? The Rights of the Unwashed Masses?

This picture is so disturbing because the methods and language of democratic civil rights movements are being used to sacrifice the educational rights of one child so that others can be spared a few minor inconveniences.  In this way, these protests are part of a larger, unsettling pattern. The past few years (or perhaps decades?) have seen a subtle shift in the way that terms such as "rights", "justice" and "democracy" are invoked in the US. More and more, these terms are being used to defend indvidual, rather than collective interests, and these individual interests are defined in increasingly narrow and selfish ways.

Mark Lilla, in a New York Review of Books article, sums this up brilliantly:

Many Americans, a vocal and varied segment of the public at large, have now convinced themselves that educated elites—politicians, bureaucrats, reporters, but also doctors, scientists, even schoolteachers—are controlling our lives. And they want them to stop. They say they are tired of being told what counts as news or what they should think about global warming; tired of being told what their children should be taught, how much of their paychecks they get to keep, whether to insure themselves, which medicines they can have, where they can build their homes, which guns they can buy, when they have to wear seatbelts and helmets, whether they can talk on the phone while driving, which foods they can eat, how much soda they can drink… the list is long. But it is not a list of political grievances in the conventional sense.

Historically, populist movements use the rhetoric of class solidarity to seize political power so that “the people” can exercise it for their common benefit. American populist rhetoric does something altogether different today. It fires up emotions by appealing to individual opinion, individual autonomy, and individual choice, all in the service of neutralizing, not using, political power. It gives voice to those who feel they are being bullied, but this voice has only one, Garbo-like thing to say: I want to be left alone.

A new strain of populism is metastasizing before our eyes, nourished by the same libertarian impulses that have unsettled American society for half a century now. Anarchistic like the Sixties, selfish like the Eighties, contradicting neither, it is estranged, aimless, and as juvenile as our new century. It appeals to petulant individuals convinced that they can do everything themselves if they are only left alone, and that others are conspiring to keep them from doing just that. This is the one threat that will bring Americans into the streets.

Welcome to the politics of the libertarian mob.

This all makes me wonder about the future of democracy, and human society more generally. While young people in the Middle East are are staging revolts to overthrow decades of repression and corruption, the Tea Party and Republican Party more generally are attacking the very notion of collective action for the common good. (See "Republicans Vote To Repeal Obama-Backed Bill That Would Destroy Asteroid Headed For Earth" for a satirical example.)

Unsettlingly, the one recent US protest movement on behalf of collective action---the showdown over collective bargaining rights in Wisconsin---has apparently failed. The result is a further weakening of unions, themselves one of the few institutional standard-bearers of the idea that we can achieve more together than apart.

The history of humanity, and indeed of life itself, is a story of transitions from the individual to the collective, from lower to higher levels of organization. This can, of course, be taken too far, as it was in the case of Communism. But happens in the other extreme, of radical individualism and resistance to all forms of organization? Are we headed for an evolutionary regression?

I don't know the answers to these questions, and I don't think they are simple. But since this trend appears to have enormous momentum, it's worth thinking about where it might lead.

(Many of the ideas in this post actually come from my partner Anna. Yay collective action!)