What Vampire Bats Can Teach Us About Reciprocity and Design

When we think about vampire bats, the first thing that comes to mind probably isn’t friendship. Yet, in the 1970s, a researcher observed something extraordinary about these blood-drinking creatures: they feed each other. At first, he assumed the bats sharing meals must be family, but after further observation, he found that wasn’t the case. These bats weren’t related—they were friends. Scientists might cringe at the thought of calling the vampire bat behavior “friendship.” They’re more comfortable with terms like “complex individualized relationships.” But no matter what you call it, the principle behind the behavior is clear: reciprocity. Reciprocity, whether among bats or humans, is a foundational element for building trust and fostering lasting relationships. 

I don’t often think about “friendship” in my work as a service designer, although it would fulfill my childhood dream of being a real-life Care Bear. But hearing about peculiar bat behavior stopped me in my tracks. One, wow, vampire bats are getting a bad rap. Then, my mind turned to reciprocity and how it shapes design. It’s a principle that can guide how we approach service design, where small acts of care and mutual benefit strengthen long-term connections with service actors. Reciprocity isn’t just foundational to building trust and demonstrating value in an experience—two things we strive for in nearly every project—but it is a biological survival mechanism and a fundamental principle that underpins relationships in human society.

Uwe Schmidt, CC BY-SA 4.0, via Wikimedia Commons

Is Reciprocity Wired into Nature?

Vampire bats live in colonies of varying sizes, roosting in caves or hollow trees where they spend most of their time. In the few minutes where they leave the roost, they spend their time hunting for their meal. They regularly feed on livestock and can even pinpoint their favorite cow in a large herd. They must feed regularly because vampire bats can only survive two to three days without blood.

Their blood-sharing bonds are crucial for survival. This reciprocal agreement is intriguing because it extends to nonkin relationships, which is rare in the animal kingdom. Researchers have observed that some individual bats have more or less relationships with others. Their blood-sharing bonds are nurtured through lower-stakes bonding mechanisms around mutual grooming. Researchers deduct that there is an advantage to having several bat buddies, or in a less anthropomorphic description, diversified feeding relationships.

One of my favorite parts about studying bioinspiration in design is the new lenses and perspectives to continue to learn from our natural surroundings. Vampire bats not only represent blood-sucking squad goals—they’re modeling a form of trust and reciprocity that could inspire any service-based individual or organization. While I haven’t been able to do my Care Bear stare and shoot rainbows out of my belly, building trust in service design is often as simple (and complex) as ensuring the service participant feels valued and heard.

Anthropology Shows Reciprocity Goes Beyond Simple Transactions

Interestingly, this idea of reciprocity in relationships goes beyond bats and has been studied extensively in anthropology. Not all reciprocity is equal. Anthropologist Marshall Sahlins identified three modes of reciprocity—generalized, balanced, and negative reciprocity. 

The Maasai have a word for their need-based reciprocity: osotua, meaning “umbilical cord.” These bonds are built on helping others when they’re in need without expecting repayment, fostering cooperation for communal survival. This is an example of “generalized reciprocity,” where giving is altruistic and doesn’t require a direct return. An example is our current service landscape with “freemium models,” where a customer can access to the basic product and service but can pay for more usage (see why all my Zoom meetings end at 40 minutes).

Balanced reciprocity, on the other hand, involves exchanges with the expectation of an equivalent return over time. The Kula ring, a ceremonial inter-tribal exchange system from the Trobriand Islands of Papua New Guinea, exemplifies this. Items like necklaces and armbands circulate to maintain long-term social bonds, with the expectation that gifts will eventually return to the giver. I can see this example on my phone. I know if I share my Duolingo streak (allez! 🇫🇷) I can be awarded more virtual currency for the app. Lastly, negative reciprocity, where one party tries to gain something for nothing, is more impersonal and focuses on personal gain. We should only use this as a model for reverse brainstorming activities on what not to do since it erodes trust.

The Kula Ring. Bronislaw Malinowski, Preface by Sir James G. Frazer, Public domain, via Wikimedia Commons

Reciprocity in Service Design 

While most humans aren’t in dire need of blood, we, too, rely on reciprocal relationships. Just as vampire bats build trust by sharing blood and sustaining bonds, we can build lasting relationships in service design through mutual exchanges that show care and understanding. When we use a service, we expect it to be there for us and to fulfill its promise—no questions asked. We’re thrilled when that service goes above and beyond, but we feel frustrated when it falls short.

Customers don’t see their cable company or credit union as “friends,” but services do mimic friendship. Think about your dentist sending you a birthday card—a small act that builds goodwill and strengthens the connection between the service provider and participant. To some extent, participants want their services to be empathetic. A driver wants their AAA tow truck driver to understand how cold and rainy it is and how desperately they want to get home. Insurance agents guiding customers out of a wrecked car with compassion and clarity are doing more than fulfilling a transaction—they’re building a personal, emotional relationship.

Customers and employees also reciprocate through loyalty, feedback, and referrals. If participants feel the service meets and anticipates their needs, they’ll stick around longer. For instance, at Harmonic, we love incorporating thank-you notes into many of our projects. This simple display of gratitude can go a long way. My favorite example is Delta’s handwritten notes for frequent flyers—a small but powerful gesture that regularly makes its way onto social media because it surprises and delights customers.

But reciprocity in design must be authentic. If the participant detects insincerity, it can harm trust. Designers need to strike a balance, ensuring participants don’t feel overwhelmed by requests or exploited for their data. The bare minimum should be to aim for a balanced relationship. Since the customer is already paying for the service, the question is: How can it fulfill its promise and build even more value? Ultimately, service design is about mutual exchanges that build trust over time—much like vampire bats.

From Vampire Bats to Service Design: A Lesson in Trust

Reciprocity is at the core of any valuable service relationship. It can be as simple as offering resources for free to build trust or providing extra care during a joyful, stressful, or mundane moment. Creating these reciprocal systems of value makes service design genuinely impactful. We’re solving problems and building relationships where participants feel understood and appreciated. So, next time you’re crafting a service, think like a vampire bat: focus on creating reciprocal, value-driven interactions that nurture lasting relationships. For example, how can you make service participants feel understood and see the value of the service? And maybe those blood-sucking, maligned little creatures will inspire you to better-designed experiences.

References

Blood buddies. Radiolab. (n.d.). https://radiolab.org/podcast/105440-blood-buddies

Fritts, R. (2021, September 23). Vampire bats take their blood meals with friends. Science. https://www.science.org/content/article/vampire-bats-take-their-blood-meals-friends

Gale, S., & Miller, D. (n.d.). Is reciprocity possible? – engage -University of Richmond. engage. https://engage.richmond.edu/about/publications/civic-provocations/reciprocity.html

Greenfieldboyce, N. (2019, October 31). For these vampires, a shared blood meal lets “friendship” take flight. NPR. https://www.npr.org/2019/10/31/774358215/for-these-vampires-a-shared-blood-meal-lets-friendship-take-flight

Interaction Design Foundation. (2024, June 28). What is the law of reciprocity? – updated 2024. The Interaction Design Foundation. https://www.interaction-design.org/literature/topics/reciprocity?srsltid=AfmBOoqYeoJyXS5rgaewGMbYRKc1Ru_BzRLMMS2LVCSmXIxFZcAw9uPs

Malinowski, Bronislaw. Argonauts of the western Pacific: An account of native enterprise and adventure in the archipelagoes of Melanesian New Guinea [1922/1994]. Routledge, 2013.

Landers, J. (2017, May 31). What a vampire bat can teach us about the economics of friendship. Smithsonian.com. http://www.smithsonianmag.com/smithsonian-institution/what-vampire-bat-teach-economics-friendship-180963492

Sahlins, M. (2013). Stone age economics. Routledge.Shaffer, L. (2022, September 21). What can vampire bats teach us about friendship?. SAPIENS. https://www.sapiens.org/culture/can-vampire-bats-teach-us-friendship/