Long before modern parenting existed, animals simply laid eggs and left. A new study published in Nature reveals how evolution transformed that neglect into nurture — and the answer, at least in ants, has less to do with inventing new brain circuitry than with repurposing an old one built for hunger.

Working with clonal raider ants, researchers at Rockefeller University discovered that evolution redeployed ancient neural systems that regulate hunger into triggers for social caregiving behavior. Because ants and mammals share similar brain-signaling systems for caregiving, and because ant caregiving behavior naturally shifts with age, the findings could help scientists understand how parenting evolved in mammals — and how the human brain changes over a lifetime.

“Our work is a prime example of how evolution seldom invents things from scratch. Evolution takes what it has and works with that, sometimes in very surprising ways.”

Daniel Kronauer, head of the Laboratory of Social Evolution and Behavior, Rockefeller University

Mapping 70 Brain Chemicals

Ant colonies maintain a strict age-based division of labor: young ants nurse larvae inside the nest, while older ants forage outside. The research team built a behavioral platform that automatically tracked caregiving interactions between individual ants and larvae, then identified and synthesized the chemical signaling molecules in ant brains, testing each one for its effect on caregiving.

“We annotated the neuropeptidome of this ant, the complete set of neuropeptides. There were 70 that we could identify. It took a lot of hard work, but now we have a set of molecules that we can investigate.”

Kay, Rockefeller University

Two opposing molecules emerged as the key switches: Neuropeptide F (NPF) promoted caregiving, while Allatostatin A (AstA) encouraged foraging. Young ants had higher NPF and lower AstA in key brain regions; older ants showed the opposite pattern. Manipulating either molecule changed behavior directly — and both responded to hunger, with starving ants behaving like caregivers and well-fed ants shifting toward foraging.

“We learned that parental behaviors build on the neural circuitry for feeding, and that makes some sense. Parental behavior is a lot about feeding — not just yourself, but your offspring.”

Daniel Kronauer

A Model for Healthy Brain Aging

Because ants naturally transition from caregivers to foragers as they age, the researchers see them as a promising model for studying how a healthy brain changes over time — a question that has received far less research attention than late-stage neurodegenerative disease.

“There’s a lot of research and funding invested in studying late-stage neurodegenerative diseases, but we actually know very little about how the brain changes throughout the normal healthspan. In ant colonies, these dynamics are central to the organization of the society.”

Daniel Kronauer

The next step for the team is mapping the neural circuitry these neuropeptides act on. Because mammals appear to use similar molecules to regulate caregiving, comparing circuits across species could help illuminate the evolutionary path parenting behavior took across the animal kingdom.

“It amazes me that similar parenting behaviors have evolved so many times in so many distinct animal lineages. Our paper suggests that the evolutionary routes to these sorts of behaviors are far more constrained than we may have naively imagined.”

Kay

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The study was published July 8, 2026, in Nature (DOI: 10.1038/s41586-026-10747-6).