Subscribe to our free daily newsletters
. Earth Science News .

Subscribe to our free daily newsletters

Game theory shows how tragedies of the commons might be averted
by Staff Writers
Atlanta GA (SPX) Nov 11, 2016

When Lake Lanier's water level drops below a certain point, calls go out for water conservation. The combination of usage restrictions and changes in precipitation eventually averts the crisis. But, when the crisis ends, water usage rebounds -until the next shortage. This photo shows conditions from the 2007 drought. Image courtesy Ed Jackson. For a larger version of this image please go here.

Lake Lanier in Georgia is the primary water reservoir serving suburban and metropolitan Atlanta. When the lake's water level drops below a certain point, calls go out for water conservation and news reports show images of the red mud shoreline. In some affected counties, water restrictions are imposed. The combination of usage restrictions and changes in precipitation eventually averts the crisis. But, when the crisis ends, water usage rebounds - until the next shortage.

Inspired by this example, researchers at the Georgia Institute of Technology have developed a theory to unite the study of behavior and its effect on the environment. In doing so, they combined theories of strategic behavior with those of resource depletion and restoration, leading to what they term an "oscillating tragedy of the commons." The research is reported in November 8 in the journal Proceedings of the National Academy of Sciences.

The study of how behavior affects resource depletion has a long history. The originating example is that of small farmers who share a common pasture. Each farmer has to decide whether to graze some or all of his flock, while also considering what actions other farmers might take. To avoid losing out to a competitor, each farmer decides to attempt to maximize the benefit by grazing as many sheep as possible. Consequently, the sheep overgraze and damage the pasture. Paradoxically, the benefit to each farmer over the long run is less than if they had cooperated and each grazed fewer sheep.

That individuals acting out of their own self-interest can be worse off than had they coordinated is termed a "tragedy of the commons" - a concept introduced nearly 50 years ago by the ecologist Garrett Hardin. (The use of the term "tragedy" denotes its inevitability). However, the originating example does not include a mechanism by which incentives for cooperation change as the resource is depleted.

"Our actions can substantively change the environment and, in turn, the changing environment influences the incentives for future action," said Joshua Weitz, who led the study and is a professor in Georgia Tech's School of Biological Sciences and director of the Interdisciplinary Graduate Program in Quantitative Biosciences. "The theory in our paper proposes a unified approach for the co-evolution of actions and environment."

Other authors on the study include postdoctoral fellow Ceyhun Eksin and graduate teaching assistant Keith Paarporn, both members of the Weitz group in the School of Electrical and Computer Engineering, as well as Professors Sam Brown and Will Ratcliff, both faculty in the School of Biological Sciences.

There are many other prominent examples of tragedies of the commons. One example is that of antibiotic resistance in microbes. The widespread use of antibiotics among humans and in agriculture selects for antibiotic resistance strains. Over time, the spread of resistance renders antibiotics ineffective for use in patients with otherwise curable infections. Hence, individuals trying to maximize their own benefit can unintentionally degrade the collective value of the antibiotics.

Another example stems from individual decisions about whether or not to vaccinate against childhood infectious diseases like measles, mumps and rubella. Crucially, a retracted study falsely linking autism to vaccination has inspired some parents not to vaccinate their children. Yet, when population levels of immunity drop, then these potentially lethal infectious diseases that had been prevented in the past will reappear in sporadic outbreaks or, dangerously, as large-scale epidemics.

"Individual agents acting in their own self-interest - trying to do what's right for them alone - can end up in a worse state than if they coordinated," Weitz said. "For example, the decision not to vaccinate increases the frequency of individuals having a dangerous, infectious disease. As people see the disease return, the incentives for vaccination change."

The research proposes a new model of evolutionary games with a feedback loop in which changes to the resource - whether it be water supplies, pastureland, antibiotics, or vaccine use - change the incentives for people to take action in their own interests. The environment and the incentives co-evolve and are tied to one another, allowing the outcome to be predicted.

"Incentives to use a lot of water when water is in short supply are different than when water levels are replete," Weitz said. "When things are bad and the commons is depleted, there may be greater incentives to cooperate than when the commons are in good condition."

Unlike in the originating example of the tragedy of the commons, Weitz and colleagues report that tragedies can recur again and again. Formally, the researchers unite game theory with evolutionary models in which both the tendency to cooperate and the state of the environment coevolve.

The theoretical research also pointed the way to a testable principle to avert the tragedy of the commons in specific application domains. For example, in their analyses, Weitz and colleagues found that averting the tragedy of the commons was only possible when cooperation was incentivized even when the environment was depleted and others continued to act to degrade the resources.

"Another lesson is that idealism matters," said Weitz, continuing, "A small group of cooperating individuals can, over time, change the social and environmental context for all and for the better."

Joshua S. Weitz, Ceyhun Eksin, Keith Paarporn, Sam P. Brown and William C. Ratcliff, "An oscillating tragedy of the commons in replicator dynamics with game-environment feedback," (Proceedings of the National Academy of Sciences, 2016).

Comment on this article using your Disqus, Facebook, Google or Twitter login.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only


Related Links
Georgia Institute of Technology
Water News - Science, Technology and Politics

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
India top court orders Punjab state to share river water
New Delhi (AFP) Nov 10, 2016
India's top court ordered authorities in northern Punjab state Thursday to share river water supplies with a neighbouring state, triggering a spate of resignations by angry lawmakers. The water dispute between Punjab and Haryana has been simmering for over a decade, after a bilateral agreement to construct a 214-kilometre (133-mile) canal connecting two rivers in the states was unilaterally ... read more

China jails 49 over giant explosions

Iraqi investigators examine mass grave site near Mosul

Brazil mine gets safety gear -- too late

Haiti aid hard to come by one month after hurricane

We gather here today to join lasers and anti-lasers

Trace metal recombination centers kill LED efficiency

Studying structure to understand function within 'material families'

Study: Math scares everyone, even physicists

Experts call on climate change panel to better reflect ocean variability in their projections

Game theory shows how tragedies of the commons might be averted

Climate, human influence conspired in Lake Urmia's decline

India top court orders Punjab state to share river water

Iceberg patrol gains faster updates from orbit

Kerry becomes first US top diplomat to visit Antarctica

Thawing ice makes the Alps grow

How much Arctic sea ice are you melting? Scientists have the answer

Supermarket demands fuelling food waste crisis: UN

Study finds link between pesticide exposure and microbiome changes

Chile's 'green gold' under threat: agar-agar algae

Drought-hit Zimbabwe farmers look to science to save crops

6.2 quake hits eastern Japan: USGS

Massive 'lake' discovered under volcano that could unlock why and how volcanoes erupt

Popcorn-rocks solve the mystery of the magma chambers

Sentinel satellites reveal east-west shift in Italian quake

Mali coup leader readies for trial over massacre

Lesotho army chief, accused of 2014 coup attempt, resigns

President says UN 'scapegoating' Kenyan soldiers in S.Sudan

Deadly clashes in CAR as France ends military mission

Neanderthal inheritance helped humans adapt to life outside of Africa

Traumatic stress shapes the brains of boys and girls in different ways

Evolution purged many Neanderthal genes from human genome

The fate of Neanderthal genes

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement