At a holiday dinner, a discussion turned too heated to continue, but a family too close to let it break them apart. The hardest conversations often happen between the people we love the most. Yet the most resilient and vibrant groups, like the most diverse ecosystems, are not composed of a single type of participant. Functional groups are dynamic tapestries woven from threads of both deep connection and striking differences.
I have a theory about how social groups function, a concept that grew from my observations of biological communities — groups of trees, rodents and other organisms. Of course there is danger in trying to harmonize ideas of nature’s biodiversity with those of human social groups. But one of the main themes of this column is that we humans are animals like all the others. So, why not take the risk on this theory of life.
For humans, social groups are often most productive when they are composed of people with shared interests, but different backgrounds. Take, for example, the Finger Lakes Bonsai Society. Its members range from college students and retirees to plant ecologists and businesspeople. This unlikely mix is brought together by a shared passion for growing tiny trees in tiny pots, trying to grow them to look like mature old trees. We joyfully trade secrets, pots, tips and seedlings. And unlike some family gatherings, we can usually agree on the main topic of conversation.
Other social groups might be formed by what we biologists call “shared ancestry” rather than shared interests. Whether it’s your parents and siblings or a sprawling network of aunts, cousins and grand-someones, families are bound by shared genes and history. These bonds, connections, and affections in a family run so deep that some believe they cannot be created outside of such a shared lineage.
Both types of groups — those brought together by ancestry and those by interests — are valuable, but in different ways. The most enriching experiences often come from a blend of the two. We don't pick our family members, but we get a front-row seat to their most frustratingly familiar habits. Nonetheless, the differences they bring to the table force us to confront different worldviews. Nothing is truer than when siblings disagree about politics. And yet, because they are family, we might listen a little longer or tolerate a little more, and if the stars are aligned, we might even start to see things differently.
Similarly, when we are united by a shared interest, the diverse backgrounds of the participants deepen our experience. Whether it's playing cards, birding or joining a book club, the differences among us broaden our worldview in a meaningful way.
Interestingly, these same dynamics play out in the natural world. At the Ellis Hollow Preserve in Ithaca, several species of oak trees live together in the same community. They have shared ancestry (all in the genus Quercus) and their shared evolutionary history gives them the traits needed to thrive in that particular forest environment. And yet, the forest isn't just oaks. It's a mix of beech, maple, birch, cherry and even magnolia trees — all from different botanical families. Despite their distinct origins, they all acquired the traits necessary to survive in that same neighborhood.
The forest is a living system where competition and cooperation coexist. Ecologists know that when two species are too similar, they compete fiercely. Families are no different, my mom and I are so much alike, when we are in the house together, we often fight over the thermostat. Yet, the related trees in the forest have typically evolved their own ways to stay out of each other's way. The addition of those species from other families, while independently evolving some of the same survival skills, brings a wealth of unique perspectives. This allows them to thrive in the same place, expressing themselves in different ways and softening neighborly interactions. In the end, diversity prevails.
Biodiversity comes from the similarities and differences between species. Each community — whether it's of rodents, milkweeds, whales or ants — is composed of some close relatives and some relatively unrelated species. They complement each other through their similarities and differences, creating functional ecosystems. Some of the differences come from their distinct backgrounds, while others come from active displacement within a family.
The lessons from the forest — that diversity from both related and unrelated members creates a resilient whole — could be loosely applied to human society. Perhaps a deeper understanding of our forests could help us build more resilient communities by embracing the complexity of who we are: a blend of what we're born into and what we choose.
Life is far too long to be taken seriously. But our relationships, like the most beautiful gardens, require a touch of both nature and deliberate cultivation. Perhaps the key is not to escape our family trees, but to plant new ones of our own choosing, and in doing so, create a richer, more diverse forest.
Anurag Agrawal is the James A. Perkins Professor of Environmental Studies in the College of Agriculture and Life Sciences. He is a field biologist and studies the Ecology and Evolution of Botany and Entomology.His column Candor and Chlorophyll runs periodically this semester, and was introduced here in 2024. He can be reached at profaagrawal@cornellsun.com. He also posts his pieces on bluesky.
