Leafcutter ant colonies, celebrated for their rigid division of labour, have yielded a startling secret: their roles can be rewired with a molecular tweak. Scientists from the University of Pennsylvania orchestrated this transformation using two tiny neuropeptides, shifting defenders into nurses and garden workers into leaf harvesters. The work, published in Cell on 9 June 2025, reveals a mechanism conserved across species, reaching mammals such as naked mole-rats—suggesting a 600‑million‑year‑old evolutionary blueprint guiding social organisation.
Research led by Daniel S. Och Penn Integrates Knowledge University Professor Shelley L. Berger focused on the neurochemistry of division of labour in Atta cephalotes, a leafcutter ant species. In these highly structured societies, ants specialise very early, with larger Majors guarding the colony, Media ants gathering leaves, and smaller Minims managing fungal gardens and caring for brood. By altering the levels of crustacean cardioactive peptide and neuroparsin‑A, researchers caused dramatic behavioural shifts: upping CCAP induced gardeners and defenders to start harvesting leaves, while reducing NPA in Majors triggered caregiving instincts.
Genetic knockdown and direct peptide injections produced rapid behavioural reassignments, echoed by transcriptomic profiles aligning with the new roles. Media ants treated with CCAP began leaf‑harvesting patterns typical of their subcaste, confirmed by gene‑expression pathways linked to foraging. Similarly, Majors with reduced NPA exhibited brood‑care behaviours and corresponding gene‑expression patterns.
What makes this finding truly remarkable is its cross‑species resonance. Molecular signatures that defined ant behaviour corresponded with those observed in Heterocephalus glaber, the naked mole‑rat—another eusocial species with task‑based worker castes. The parallel suggests that neuropeptide‑driven social regulation may trace back to a common ancestor deep in evolutionary history. “We were amazed to see the apparent similarity of gene regulation between nurses and foragers of ants compared to naked mole‑rat mammals,” Berger said, noting that these parallels were unexpected given the vast evolutionary gulf.
The study also hints at deeper biological links, particularly regarding insulin signalling and longevity. Leafcutter ant expression patterns showed interplay with insulin pathways previously associated with lifespan control. Naked mole‑rats are known for exceptional longevity, often living beyond 37 years—almost unheard of in rodents—and for their cancer resistance and negligible ageing.
Members of Berger’s team, including Michael B. Gilbert and Karl M. Glastad, emphasised the role of these neuropeptides as modulators rather than executors of behaviour. Their study, based on rigorous gene expression analyses from both ants and naked mole‑rats, pointed to a convergent evolution model: similar molecular tools repurposed by different species to achieve comparable social complexity.
Behavioural plasticity within ant castes was previously explored by examining epigenetic factors and brain structure. Yet, this experiment demonstrates that acute chemical manipulation can override morphological predispositions, offering a dramatic proof of role reversibility in one of nature’s most disciplined societies. The findings imply latent flexibility—ants may be much more dynamic in their roles than previously believed.
Experts note that while role switching in ants may feel ethically distant, the insights have broader ramifications. Neuropeptides are key regulators in diverse taxa, humans included. For instance, oxytocin in humans influences parental care; the ant study opens questions about universal behavioural circuits shaped by peptides. A deeper understanding of these molecular circuits could eventually inform approaches to social behaviour disorders or age‑related decline.
However, some caution that translating findings from invertebrates and subterranean rodents to humans is premature. Neuropeptide systems and brain architectures vary widely. Moreover, nudging behaviour with peptide injections in controlled lab settings does not equate to social engineering in complex natural environments.
Still, the implications are profound. The discovery of CCAP and NPA as behavioural switches not only rewrites our understanding of ant societies but also challenges our notions of how ancient molecular codes govern social life. It invites a reevaluation of social evolution, suggesting that similar neurochemical pathways could underlie task allocation in humans, mammals, insects—and maybe even further back in the tree of life.
