Cats & Humans: Rethinking a Complex Mutualism | Live Science

The relationships between species are rarely static. What begins as a mutually beneficial arrangement can, over time, shift toward exploitation. Rob Dunn, a professor of applied ecology at North Carolina State University, explores this dynamic in his new book, “The Call of the Honeyguide: What Science Tells Us About How to Live Well With the Rest of Life”, focusing on a particularly intriguing case: our long and complex relationship with domestic cats.

For millennia, humans and cats have shared space, a partnership often taken for granted. But what do we truly gain from this arrangement? Dunn’s work prompts a re-evaluation of what constitutes a mutualism, suggesting that our connection with cats may be more parasitic than symbiotic, at least from a strictly Darwinian perspective. The sheer scale of resources devoted to feline care is striking: Americans alone provide approximately 15 billion calories worth of food to house cats daily – a quantity comparable to the daily caloric consumption of New York City’s human population.

The Evolution of a Partnership

The story begins with the African wildcat, Felis silvestris lybica, whose range overlapped with the earliest human agricultural settlements in the Levant. As humans began storing grain, these wildcats were drawn to the resulting rodent populations. This initial interaction was likely mutually beneficial: cats controlled pests, and humans inadvertently provided a food source. This co-existence led to a process of “tameness,” where cats learned to tolerate human presence, and humans, in turn, became accustomed to their feline companions.

Archaeological evidence, including the discovery of a carefully buried cat alongside a human in Cyprus dating back 9,500 years, suggests that humans actively transported cats, likely as valued pest control agents. Cats weren’t simply following humans. they were being brought along, even if the process involved a few scratches along the way. This early stage of the relationship appears to have been a genuine mutualism, with both species benefiting from the arrangement.

From Pest Control to Companionship

However, as human settlements grew into larger urban centers, the effectiveness of cats as pest control likely diminished. The sheer volume of grain stored in massive granaries likely exceeded the capacity of even a large cat population to significantly impact rodent numbers. Around 3,500 years ago, depictions of cats in Egyptian art began to change. They were no longer portrayed as hunters but as domestic companions, often found lounging under chairs and even wearing leashes. This shift suggests a change in the nature of the relationship.

The role of cats transitioned from practical utility to something more akin to companionship. This is not to say that cats ceased to hunt altogether – Roman archaeological sites reveal cats with the remains of multiple rodents in their stomachs – but the primary benefit they provided to humans may have evolved beyond pest control. The question then becomes: what do humans gain from this relationship now?

Rethinking Mutualism: Beyond Rodent Control

Dunn’s work challenges us to broaden our understanding of mutualism. If the primary benefit of cats is no longer pest control, what is it? The answer, he suggests, may lie in the less tangible benefits of companionship, emotional support, and even a sense of connection to the natural world. While difficult to quantify, these benefits are nonetheless real and may explain the enduring popularity of cats as pets.

The sheer number of cats living alongside humans today is unprecedented. With an estimated global population of half a billion, cats have largely replaced wild feline predators like tigers, lions, and leopards in human-dominated landscapes. We’ve traded the fear of jaguars for the affection of “Mr. Whiskers,” a testament to the profound impact humans have had on the feline world.

Genetic Insights into Domestication

Recent genetic studies, led by Claudio Ottoni at the University of Padua, have shed light on the domestication process. Analysis of ancient cat remains has revealed that early cats living alongside humans were genetically indistinguishable from their wild ancestors. This suggests that the initial stages of domestication involved a process of self-domestication, where cats with a greater tolerance for human presence were more likely to thrive in human settlements.

The cats essentially chose to live with humans, drawn by the abundance of prey. Humans, in turn, tolerated their presence, recognizing their value as pest control agents. This initial co-existence laid the foundation for the deeper bond that exists today.

What Comes Next: A Broader Perspective on Inter-Species Relationships

Dunn’s work isn’t just about cats; it’s about the complex web of relationships that connect humans to the natural world. It encourages us to consider the often-overlooked mutualisms that shape our lives, from the microbes in our gut to the honeyguides that lead humans to beehives. Understanding these relationships is crucial for fostering a more sustainable and harmonious coexistence with other species.

The future of human-animal relationships will likely involve a continued blurring of the lines between mutualism and parasitism. As we continue to alter the planet, we will inevitably create new opportunities for species to exploit our resources. However, by recognizing the interconnectedness of all life, we can strive to create relationships that are truly beneficial for all involved. Further research into the genetic and behavioral changes that occurred during cat domestication, as well as studies examining the impact of cats on urban ecosystems, will be essential for gaining a deeper understanding of this enduring partnership.