Knowing how to send and interpret signals is an essential part of both diplomacy and war. Political scientists have recognized that costly signals – gestures and actions that involve significant cost or risk – are central to politics and diplomacy since modeling doyen James Fearon built his Ph.D. thesis around the concept in the 1990s. Because these signaling systems are pervasive in nature (many of these strategies arise independently and repeatedly to solve common problems suggesting evolutionary pressure to select strategies offering the most success at the least cost), their underlying strategic logic has important implications to foreign policy challenges we face today. By capitalizing on solutions derived by evolution over 3.5 billion years of life on Earth, we may identify ideas that otherwise might not have been explored in a policy context potentially offering quick, novel, and effective options to increase strategic and combat effectiveness. Here we present 8 lessons from evolution for political science.

Lesson 1. Honest signals will be costly

The power of costly signaling in the animal world is captured in the famous example of the peacock’s tail. A series of studies have demonstrated that females select males with the longest and most elaborate tails. The benefits of such a selection criterion are clear: males that are able to allocate sufficient resources to grow this long tail, make it colorful, and keep it clean and healthy looking, survive despite their handicap. Males that can do this have energy to burn; they radiate their quality. The tail is thus an honest advertisement of the skills of acquiring food, avoiding predators, and controlling parasites and pathogens. Females choosing these showy males will ensure high quality genes being transmitted to their offspring.
Indeed, from this and many other studies of signaling and communication in a diversity of mammals, birds, fishes, and insects, we can conclude that a common feature of animal communication is that costly signaling is valued by receivers, not just the sender, and in a wide range of settings. This biological rule has important implications for several aspects of foreign policy including making positive gestures during negotiations.

An effective negotiator must communicate honesty to the receiver, thereby inducing trust. Negotiations proceed with repeated positive feedback: the receiver needs to honestly signal trust back to the negotiator. Complicating this interaction is the cross-cultural nature of diplomacy that may result in the misinterpretation of honest signals. Positive gestures are one way of building trust. To be effective in the long term, positive gestures must be costly, yet many positive gestures in foreign policy are ritualized into protocol whereby there are formal and invariant rules by which states, and their emissaries, interact. If they are expected as routine, they are unlikely to be valued—seen as a result of the situation rather than any cooperative disposition of the actor.#

Lesson 2: Ritualized signals may have little value, but may be used strategically

In animal systems, ritualized signals contain little information and do not vary much from individual to individual; consider the first, stereotypical behaviors in a courtship sequence. To avoid confusion, such displays are often ritualized. This lack of variation means that there is less of an opportunity for a receiver to associate a display with its underlying cost. And, while ritualized gestures might be commonplace ways of building trust – consider shaking hands, smiling, engaging in small talk – these displays may not be as effective as a genuinely costly display. This is not to entirely discount the importance of these displays, because effective cooperation between individuals is costly in that it takes time to develop and requires individuals to evaluate each other’s reputations that are built over time. However, for now, let’s consider isolated responses.

Systematically reducing the value of a signal to a receiver may be used strategically. The Egyptians capitalized on what became to Israelis a ritualized signal—maneuvers on the Israeli border in the months preceding the Yom Kippur War. Before attacking Israel, Egypt ran 40 military exercises on Israel’s borders#. This led Israel to discount the threat of a troop buildup on their border and enhanced its vulnerability.

However, there are also costs to ritualization. The recently scrapped Homeland Security Threat Level remained unchanged for years before being eliminated. What message did this invariant ritualized message send to travelers—or to prospective terrorists? Indeed, one lesson from nature is that one must consider the nature of the recipient in order to properly design a signal. And, in some cases, such ritualized signals may become meaningless and counterproductive.

Lesson 3: Unexpected signals may be more effective

Following a natural disaster, nations offer assistance to other countries. An offer of one million dollars in aid from a poor country is a much more meaningful contribution than the same offer from a wealthy one. And, individual citizens lining up to spontaneously help others (as often occurs following natural disasters) are truly meaningful gestures. For instance, following devastating 1999 and 2011 earthquakes in Turkey, members of the Israeli public spontaneously and immediately organized to collect food, clothing and other emergency necessities for Turkish citizens. While many governments formally responded, including the Israeli government, such responses are difficult to interpret since they are routine and likely to be strategically motivated. The spontaneity of the Israeli public response however appeared to be a sincere offer of help. The key insight is that it is not the absolute value, but rather the value relative to ability, and the sincerity of the donation that is likely to define a trustworthy display. Humans suffer from the so-called “correspondence bias”, which makes us more likely to assume the behavior of other actors is a result of their fundamental character, whereas our own behavior is a result of reacting to the situation—especially if the act impacts on us negatively. However, when the act impacts on us positively, we are more likely to assume the actor was motivated by situational constraints.

Lesson 4: Threats should be costly

Conversely, natural systems show us that negative gestures such as threats may also have to be costly to be effective. A striking lesson from evolution is that adversaries should organize their threats into a gradually escalating sequence, resorting to all-out fighting only if the less costly, earlier signals fail to induce their opponent to back down. Red deer competing for mates strut threateningly side-by-side, then bellow at each other, and only then lock antlers if one individual does not back away. The logic is impeccable: if the adversaries are badly mismatched, they will realize it during the first phase and back down quickly, saving both from wasting further time and energy. If the payoff for winning is not great, individuals should not escalate. But, if the payoff is great, more subtle differences will be detected at the second stage, again a mutually beneficial outcome. Truly dangerous fights will only occur when both have proved themselves to be so evenly matched that signaling alone cannot distinguish between them. Over millions of years, natural selection has crafted a finely-tuned “playbook” of signaling and escalation for species’ to work from as they attempt to resolve their conflicts of interest without getting killed in the process.

Humans face similar problems, and bargaining theories of war have investigated similar problems of incremental signals. However, evolution offers a useful new perspective on this because we face types of conflict that our ancestors never encountered, and thus to which our responses have not been molded by selection. In a world of cyber-warfare, weapons that kill at a distance, and remote command and control far from the battlefield, our evolved signaling mechanisms neither convey messages to the enemy nor bring us direct feedback (e.g., drone pilots fight thousands of miles from the battlefield, the sources of computer worms like Stuxnet are opaque and difficult to trace). This means we may expect an evolutionary “mismatch” between our behavior and our environment and may lead to unintended and un-checked escalation. Rival states may exchange costly signals prior to launching into war, for example military parades that display cutting edge technology, power projection through naval port calls, elevating level of alert status for forces as well as funding levels for security and defensive activities. However, different strategies and their deployment between adversaries in a crisis may lead to confusion and potentially catastrophic outcomes. Considering the stakes in incidents such as the nuclear alerts ordered by President Kennedy in the Cuban Missile Crisis, by Nixon during the Yom Kippur War of 1973, or North Korea’s response to accusations that it torpedoed and sank a South Korean warship in March 2010 – the question becomes a very urgent one.

Evolutionary thinking provides guidelines for formulating an appropriate policy response, particularly when it is unclear whether adversaries are following the same rules. Just as in conflicts in natural systems, honest signaling of intention in a series of reciprocal steps is the best way to obtain a peaceful resolution. And, developing a reputation for honest signaling is a powerful force in obtaining trust. In the absence of a reputation for honest signaling, it is difficult to know whether to escalate up or down in negotiations.

Lesson 5: State apologies should be costly

To be successful apologies must be costly. The cost of an apology is the political risk to the person or administration apologizing, and broader costs to pride and well-being within an apologizing society. This may explain why meaningful apologies are not very common, and most apologies happen long after the incident that stimulated it. Apologizing, after all, is a political calculation. Waiting until there is no political cost because opponents have died or moved on to some other issue lessens the value of an apology. In 1998, President Clinton apologized for his administration’s inaction during the Rwandan genocide four years earlier—an unusual and costly act for a President still in office. Israel and Germany have good diplomatic relations and there is also friendship among the populations (many Germans travel to Israel) and this is remarkable given the devastation in the living memory of so many Jews and Israelis. At least three factors were probably important: 1) public apologies which were followed up by real costs such as 2) reparation payments, and 3) a schooling system that makes German children more educated about the Holocaust than probably any other children outside Israel in the world. Nelson Mandela probably recognized the huge value of costly apologies when he set up the reconciliation commissions in South Africa after the fall of the apartheid. Rather than sending all whites involved in the apartheid state to jail, he created a forum for them to apologize face to face with their victims and wipe the slate clean.

Insincere apologies may be particularly costly. Then Secretary of Defense Donald Rumsfeld’s apology about the Abu Ghraib prisoner abuse backfired when he tried to also explain that there was Arab mis-understanding of American culture which could not condone such behavior. This apology was widely regarded as a flop. Japan’s apologies for atrocities in China during World War II remain unvalued by the Chinese because of Japanese dignitaries’ visiting the Yasukuni Shrine to Japanese war dead, which includes the remains of convicted war criminals.

Lesson 6: Humans (and animals) are not necessarily rational: symbolic concessions may be useful

Studies of animals (and humans) also show us that in certain circumstances, individuals do not make economically rational decisions. There is healthy debate about whether these are indeed costly mistakes or evolved strategies. However, there are some lessons from this observation for security and policy.

One of these is that low cost actions may sometimes have a high value to recipients of these actions and, as Jeremy Ginges and colleagues found, the economically rational offers are not necessarily what people will accept#. Indeed, people’s core values must be recognized, often by symbolic concessions. In their research asking both Palestinians and Israelis about what sort of incentives might help move a peace process forward, they found that financial incentives were viewed very negatively, but symbolic concessions, such as apologies for past actions and removing anti-Semitic material from textbooks, went far both with leaders and citizens. Indeed, offers of reparation without the necessary symbolic concessions were viewed negatively. Here again, Nelson Mandela recognized the importance of symbolic concessions when he publicly supported the Springbok rugby team, even though, initially, his black supporters wanted to disband this symbol of apartheid. Understanding that economically irrational behavior is common and that symbolic concessions have great value may be essential in negotiating through seemingly intractable political quagmires (e.g., such as those in North Korea, Iran, and, as Atran and Ginges# write—Israel/Palestine).

Lesson 7: Weaker parties will advertise the strength of their conviction

Obviously not all diplomatic interactions and conflicts are between state actors. Are there unique insights for interactions with non-state actors? A characteristic of a state interacting with a non-state actor is power asymmetry.
Consider the rapid spread of suicide terrorism among weak and disenfranchised organizations fighting a stronger state. With the exception of Kamikaze pilots in WWII, we have not seen two strong opponents in the 20th century use suicide attacks as a military strategy. Indeed, one could argue that the Japanese only resorted to Kamikaze pilots once they realized they were losing because of a loss of pilots, fuel, and weapons. One interpretation of this is that being able to marshal legions of self-sacrificial volunteers creates an honest indicator of the amount of displeasure and the intention to continue fighting that the weaker party faces. When non-state actors fight against democratic state actors, the public opinion is as much a target as the military and the weaker party often wins by turning public opinion against ongoing conflict. Thus, in such asymmetrical combat, such as Chechens against the Russians, Hamas against Israel, or the LTTE against the Sri Lankan government, we should expect the weaker party to work hard to impress upon the stronger party the strength of their conviction. Suicide terrorism may be such a potent signal because it is an unbluffable signal of commitment.

Political scientists have recently recognized this, and have characterized five distinct ways in which terrorists use costly signals to advance their agenda: attrition (wearing down the enemy), intimidation (of opponents in their own population), provocation (of the enemy to violence and collateral damage that consolidates resistance against it), spoiling (of a peace process), and outbidding (of domestic rival parties)#. Moreover, natural systems show us that self-sacrifice is often associated with high relatedness. Social insect workers will die to help their highly-related group persist and the same logic might explain situations in which tightly knit groups, bound by kinship and religion, are willing to make the ultimate sacrifice. Holding this lens over the problem of terrorism clarifies the strategic logic that should guide a policy response.

Lesson 8: Signals are often species specific: it’s essential to know your audience

Species differ in their signals that are often directed to conspecifics. Indeed, divergent communication signals are used to ‘isolate’ species from each other and prevent costly, but mis-guided fights, and potentially wasteful reproductive attempts with the wrong species. The final insight comes from the widespread evolution of species-specific signals: it’s essential to know your audience in order to communicate effectively to it and the same signal may mean very different things to different audiences.

Consider how two populations may have difficulties communicating. The United States botched the messaging to the Muslim world after killing Osama bin Laden. To the audience in the United States there was a low cost propaganda release of video of bin Laden sitting on the floor watching a small TV aimed at demonstrating what a miserable and pathetic fellow the man was. But to would-be jihadis, the actual effect was the opposite. They saw a leader living in humble conditions—a positive image under Muslim law. It was a low cost, culturally blind signal sent by the United States that was filtered and amplified though Islamic culture and tradition into a demonstration of the ultimate high-cost sacrifice of the man for his people.

The lesson is clear: be sure you know who your audience is before signaling and realize that the same message can be interpreted quite differently by different audiences. A low-cost signal to one audience could illustrate high-cost behavior to another audience.


While humans, like every other organism, have a unique evolutionary history, the rules of evolution and natural selection act on us all. More work is needed to disentangle the logic of individual versus group selected mechanisms on policy, but identifying these rules will inevitably create more insights about successful strategic behavior. Importantly, nature’s rules are all around us just waiting to be discovered and explored to see whether they have modern-day applications.


Atran, Scott, and Jeremy Ginges. 2009. How words could end war. New York Times 24 January:WK12 (New York Edition).
Fearon, James D. 1995. Rationalist explanations for war. International Organization 49(3):379-414.
Ginges, Jeremy, Atran, Scott, Medin, Douglas, and Khalil Shikaki. 2007. Sacred bounds on rational resolution of violent political conflict. Proceedings of the National Academy of Sciences 104(18):7357-7360.
Husain, Ed. 2011. Did U.S. botch message with bin Laden videos? http://www.cfr.org/terrorism/did-us-botch-message-bin-laden-videos/p24939
Kydd, Andrew H., and Barbara F. Walter. 2006. The strategies of terrorism. International Security 31(1):49–80.
Rabinovich Abraham. 2004. The Yom Kippur War: The Epic Encounter That Transformed the Middle East. New York: Schocken Books.
Sagarin, Raphael D., and Terrence Taylor (eds.) 2008. Natural Security: A Darwinian Approach to a Dangerous World. Berkeley: University of California Press.
Schmitt, Eric. 2010. U.S. offers aid to rescue Pakistanis and reclaim image. New York Times, 15 August:A6 (New York Edition).

Published On: February 14, 2012

Daniel Blumstein

Daniel Blumstein

Daniel Blumstein is a Professor and Chair of the Department of Ecology and Evolutionary Biology at UCLA, and a Professor in UCLA’s Institute of the Environment and Sustainability. He received his PhD at UC Davis in animal behavior, and had postdoctoral fellowships at the University of Marburg (Germany), The University of Kansas, and Macquarie University (Australia). He is a behavioral ecologist broadly interested in the evolution of behavior and the application of behavioral and evolutionary principles to policy, health, and defense. He has studied the behavior and ecology of mammals (including humans), birds, fish, lizards, hermit crabs, and sea anenome and runs the 50+ year project studying the behavioral and evolutionary ecology of yellow-bellied marmots at the Rocky Mountain Biological Laboratory in Gothic, Colorado. The author of over 200 scholarly works and five books, his most recent books include: “A Primer of Conservation Behavior” (Sinauer Associates, 2010, with Esteban Fernandez-Juricic), “The Failure of Environmental Education (And How We Can Fix It)” (University of California Press, 2011, with Charles Saylan), and “Eating Our Way to Civility: A Dinner Party Guide” (a Kindle and Apple e-book, 2011).

Scott Atran

Scott Atran

Scott Atran is an anthropologist and psychologist who studies how cognitive and biological dispositions, and cultural preferences and values, shape social structures and political systems and drive group conflict. He is co-founder of Artis International and the Centre for the Resolution of Intractable Conflict at the University of Oxford; Research Professor at the University of Michigan’s Gerald Ford School of Public Policy; Research Fellow at Oxford University’s Changing Character of War Centre; Emeritus Director of Research at France’s Centre National de la Recherche Scientifique; and advisor to the UN Security Council on counterterrorism and issues of Youth, Peace, and Security. His work and life have been spotlighted on television, radio, internet blogs and podcasts, and in the popular and scientific press, including feature and cover stories of the New York Times MagazineThe Chronicle of Higher EducationNature and Science. He is the author of Talking to the Enemy Faith, Brotherhood, and the (Un)Making of Terrorists (2010) published by HarperCollins.

Michael Hochberg

Michael Hochberg

Dr. Hochberg’s research focuses on interdisciplinary applications of the evolutionary process. he is interested in how environmental conditions impact the genetics and expression of virulence, and what the implications are in areas ranging from cooperation in social groups, to the management of virulent pathogens, to population diversification and speciation. His laboratory uses a combination of mathematical modeling and experimental evolution with the system Pseduomonas fluorescens SBW25 – lytic bacteriophage PHI2.

Dominic Johnson

Dominic Johnson

Dominic Johnson is Alistair Buchan Professor of International Relations at the University of Oxford. He received a D.Phil. from Oxford in evolutionary biology, and a Ph.D. from Geneva University in political science. Drawing on both disciplines, he is interested in how new research on evolution and human biology is challenging theories of international relations, conflict, and cooperation. For the 2012-2013 academic year, he is co-leading a project on evolution and human nature at the Center of Theological Inquiry in Princeton.

Rafe Sagarin

Rafe Sagarin

Rafe Sagarin is a marine ecologist at the Institute of the Environment at University of Arizona. Rafe’s research includes everything from the historical and current sizes of intertidal gastropods (snails) to developing better ideas for national security, based on natural security systems. He is particularly interested in the Sea of Cortez, or Gulf of California, its ecological history, and the fascinating people past and present who have lived, worked, researched and journeyed there.

Richard Sosis

Richard Sosis

Richard Sosis is James Barnett Professor of Humanistic Anthropology at the University of Connecticut. His work has focused on the evolution of religion and cooperation, with particular interests in ritual, magic, religious fertility, and the dynamics of religious systems. To explore these issues, he has conducted fieldwork with remote cooperative fishers in the Federated States of Micronesia and with various communities throughout Israel.  He is cofounder and coeditor of the journal Religion, Brain & Behavior, which publishes research on the bio-cultural study of religion.

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