In the intricate societies of eusocial insects, where cooperation is paramount and roles appear rigidly assigned, a groundbreaking study led by Penn Integrates Knowledge University Professor Shelley Berger has unveiled a molecular key that can unlock behavioral plasticity among leafcutter ants. Atta cephalotes, known for their strictly divided labor based on physical morphology and size, are now revealing a deeper layer of complexity: neuropeptides capable of overriding the traditional, body-size-driven caste system to reprogram individual ants’ behavior.
Leafcutter ant colonies are marvels of natural engineering, with a precise and hierarchical division of labor. Majors, the largest ants, act as sentinels and defenders; Media workers harvest leaf material; Minor ants serve as caretakers; and the tiny Minima tend fungal gardens and brood. These roles have long been associated with physical specialization. However, Berger’s team has shown that this morphological determinism is not absolute. Instead, chemical signaling via neuropeptides enables ants to transition fluidly between roles, a finding that challenges long-held assumptions about the fixed nature of insect social roles.
Central to this discovery are two neuropeptides: crustacean cardioactive peptide (CCAP) and neuroparsin-A (NPA). Elevated CCAP levels in Media ants promote their characteristic leaf-harvesting behavior, and experimental increases of CCAP in other castes induce similar tasks. Conversely, NPA is abundant in Major ants and is associated with their aggressive, defensive behaviors; lowering NPA levels can switch Majors to brood-care roles typically reserved for Minors. This suggests that behavioral roles are modulated through dynamic neuropeptide signaling rather than immutable physiological traits.
The research incorporated innovative experimental designs, including 3D-printed behavioral arenas that allowed researchers to track and quantify interactions between ants and their environment—leaf material, brood, and fungal gardens. By manipulating neuropeptide expression in these controlled settings, the team demonstrated reproducible shifts in task allocation. These behavioral transitions underscore a neurochemical plasticity that acts atop the physical caste framework, introducing a new paradigm for understanding eusocial insect societies.
Intriguingly, the team extended their molecular investigations beyond insects, drawing parallels with eusocial naked mole-rats—mammals renowned for their cooperative, caste-like colony structures. Although naked mole-rats lack identical neuropeptides such as NPA found in ants, similar conserved gene-expression pathways govern social role differentiation. The leafcutter ant neuropeptides even activated receptors in naked mole-rat brain tissue, revealing an ancient and convergent mechanism for regulating social behaviors spanning over 600 million years of evolutionary divergence.
This cross-phyla convergence suggests deep evolutionary roots for behavioral regulatory mechanisms. The findings imply that the neuropeptide-driven shifts in role allocation might rely on conserved signaling cascades shared among diverse animal taxa, highlighting fundamental biological principles that transcend species boundaries. Such revelations pave the way for comparative research into social cognition and behavioral flexibility across the animal kingdom.
Moreover, the study uncovered surprising links to insulin-like signaling pathways, which are classically associated with metabolism and aging. Specifically, the insulin-like peptide Ilp1 was co-expressed alongside NPA, hinting at a complex interaction between metabolism-regulating hormones and neuropeptides in modulating social behaviors. This novel intersection opens up compelling questions about how metabolic states may influence caregiving, foraging, and defense within social groups.
Maxxum Fioriti, a graduate researcher and co-author, speculated that this neuropeptide-insulin nexus could have implications for understanding maternal behaviors and disorders in humans. If insulin signaling pathways play a role in caregiving behaviors across species, metabolic diseases such as insulin resistance or diabetes might contribute to altered social behaviors or post-partum mental health conditions. These translational insights elevate the biological significance of the findings far beyond ant colonies.
Beyond immediate behavioral effects, Berger’s team is exploring the durability of these neurochemical reprogramming events and their relationship to lifespan plasticity. In eusocial insects, reproductive queens often exhibit dramatically longer lifespans than sterile workers. The researchers posit that epigenetic mechanisms—heritable changes in gene expression without DNA sequence alterations—may underpin both behavioral and lifespan plasticity, offering fertile ground for future research into aging and rejuvenation.
The findings raise profound questions about how long-term behavioral modifications are maintained and whether similar neuropeptide and epigenetic pathways operate across species to modulate both social roles and longevity. Comparative studies in ants and naked mole-rats, species exhibiting extreme lifespan differences linked to social hierarchy, could unravel the molecular basis of aging in social organisms.
Technologically, the use of 3D-printed environments combined with transcriptomic analyses marks a methodological leap forward in behavioral genetics. This fusion of sophisticated behavioral assays and molecular techniques enables precise dissection of how specific neuropeptides cascade through gene regulatory networks to elicit complex behavioral phenotypes. The conceptual framework resembles a molecular Rube Goldberg machine, where neuropeptide-receptor interactions trigger a cascade effect ultimately reshaping ecological roles.
Collectively, these discoveries redefine the canonical view of eusocial behavior as purely morphologically predetermined. Instead, they highlight the critical role of neurochemical signaling in coordinating and reprogramming social roles dynamically, offering a versatile toolkit for adaptation within colonies. The evolutionary conservation across taxa further signals that similar mechanisms might underpin social plasticity in mammals, including humans, albeit with added layers of complexity.
This research thus charts a transformative path forward, linking molecular neurobiology, social behavior, and evolutionary biology under a unified conceptual umbrella. As we increasingly appreciate the chemical and genetic underpinnings of social roles, new frontiers emerge in neuroscience, aging research, and even psychiatric disorders. The leafcutter ant stands as a compelling model organism illuminating universal principles of behavioral plasticity and social coordination.
In essence, Shelley Berger and colleagues have cracked a code embedded deep in the genomes and neurochemical pathways of some of Earth’s most disciplined societies. Their work not only challenges entrenched paradigms about division of labor but also bridges disciplines from molecular genetics to ecology, promising to reshape our understanding of how social behaviors arise, persist, and evolve.
Subject of Research: Animals
Article Title: Neuropeptides specify and reprogram division of labor in the leafcutter ant Atta cephalotes
News Publication Date: 11-Jun-2025
Web References: https://www.cell.com/cell/fulltext/S0092-8674(25)00573-2
References:
- Fioriti et al., "Neuropeptides specify and reprogram division of labor in the leafcutter ant Atta cephalotes," Cell, DOI: 10.1016/j.cell.2025.05.023
Image Credits: Tierney Scarpa
Keywords: Social cognition, Experimental psychology, Behavior genetics, Gene identification, Genetic analysis, Evolutionary genetics, Behavioral neuroscience, Signal transduction
