The key finding
A 2026 study published in Philosophical Transactions of the Royal Society B reveals that both rats and cockroaches demonstrate collective intelligence—the ability of groups to outperform individuals in problem-solving and decision-making—but through remarkably different mechanisms. While cockroaches rely on ancestral, non-cognitive processes that lack complexity, rats exhibit sophisticated social traits found in primates, including cultural learning, distributed decision-making, empathy, and cooperation. The researchers propose that comparing these two ecologically successful generalists helps reveal which features of collective intelligence are universal properties of group behavior and which depend on specific cognitive adaptations that evolved over time.
What the study looked like
This was a conceptual and comparative analysis rather than a traditional experiment with controlled interventions. The researchers examined existing literature on collective behaviors in rats (genus Rattus) and cockroaches (order Blattodea), focusing on how these two groups—both highly successful ecological generalists that thrive in diverse environments—achieve collective intelligence through different pathways. The authors developed a typology of collective intelligence mechanisms, categorizing them into five types: self-organized coordination, distributed decision-making, cooperative problem-solving, statistical aggregation, and culture with cultural improvement. By systematically comparing how rats and roaches fit into this framework, the study aimed to identify evolutionary design principles underlying group intelligence across species with vastly different cognitive capacities.
Why researchers think this happened
The authors propose that collective intelligence evolved along multiple pathways, with simpler mechanisms serving as building blocks for more complex ones. Cockroaches represent an ancestral approach: their collective behaviors emerge from self-organized coordination and statistical aggregation—essentially, simple rules followed by individuals create sophisticated group outcomes without requiring cognitive complexity. Rats, sharing similar ecological niches with cockroaches (both are opportunistic, adaptable species), layered additional cognitive mechanisms on top of these basic processes. The researchers suggest that rats’ primate-like social traits—empathy, cultural transmission, cooperative problem-solving—evolved because these cognitive adaptations provided advantages in their social environments. This layering hypothesis implies that collective intelligence isn’t a single phenomenon but rather a spectrum of mechanisms that can be mixed and matched depending on evolutionary pressures. The comparison reveals that similar collective outcomes (successful group coordination, effective decision-making) can emerge through entirely different underlying processes.
How to read this carefully
This study is a theoretical framework and literature review rather than new empirical data, meaning its conclusions depend on how well existing research has characterized these behaviors in both species. The typology proposed is useful for organizing thinking about collective intelligence, but categories in biology rarely have clean boundaries—real animal behavior likely blends multiple mechanisms simultaneously. Additionally, while the authors identify differences between rat and roach cognition, the study doesn’t establish causal relationships between specific cognitive abilities and collective outcomes. The comparison is limited to two taxonomic groups, so generalizations about evolutionary principles should be considered preliminary until tested across broader species samples. Finally, determining what counts as “cognitive complexity” versus “simple rules” can be subjective and may reflect human bias about what constitutes intelligence.
What this means for everyday life
This research invites us to reconsider what intelligence means—both in animals and potentially in human systems. The finding that cockroaches achieve collective problem-solving without individual cognitive complexity suggests that group-level intelligence can emerge from surprisingly simple individual behaviors, a principle that applies to human organizations, online communities, and even artificial intelligence systems. For readers interested in teamwork or organizational behavior, the rat-versus-roach comparison offers a reminder that effective group outcomes don’t always require every member to be highly skilled; sometimes the right simple rules and information-sharing structures matter more. It also highlights that empathy and cultural learning—traits we often consider uniquely human or primate—may have evolved in rats precisely because they enable more flexible collective responses to changing environments, suggesting these capacities have practical survival value beyond abstract moral considerations.