This special collection emerged from a January 2025 workshop at the National Institute for
Theory and Mathematics in Biology on “Biological systems that learn.” Living systems are
composed of the same atoms and obey the same physical laws as nonliving matter, yet they
routinely accomplish remarkable functions: proteins regulate catalytic activity with exceptional
specificity and efficiency; cytoskeletal networks maintain strain memory and rigidity
homeostasis while continuously disassembling and reassembling; sheets of originally
homogenous cells develop into specialized organs; mammalian vascular networks distribute
oxygen and nutrients throughout organisms; olfactory systems identify odors on top of strongly
fluctuating backgrounds. The constituents—whether amino acids, cells or organisms
themselves—perform their staggeringly intricate ballets reliably and without centralized control,
even under challenging and changing conditions. Despite immense progress in identifying
constituents and their interactions in biological systems, however, our understanding of how such behaviors emerge remains fragmentary at best.
In this special collection, we gather a number of papers to illustrate how physical
matter–whether biological or non-biological–can be imbued with function. All of these systems
can be described as tunable matter—physical matter with many adaptive degrees of freedom that are individually adjusted to satisfy design constraints as well as physical constraints to produce function. By tunable matter, we mean collectives of heterogeneous physical components whose effective interactions, coupled dynamics, or internal states (degrees of freedom) can be individually tuned to satisfy design and physical constraints required for collective function, much as weights are individually adjusted in artificial neural networks (ANN). Unlike ANNs, however, biological systems do not have access to central processors, so must either be tuned by mutation and selection, like the genome, or by a decentralized tuning process that requires only limited information accessible to the individual components, like the brain. The tunable matter paradigm generalizes this logic beyond the genome and brain, extending it to new classes of degrees of freedom, tuning processes, and biological functions. According to this approach, a useful route to understanding a given biological function is to identify the tunable degrees of freedom and tuning processes that lead to it. Many of the papers in this collection do precisely that–they show how interesting functions can emerge from degrees of freedom and tuning processes that are known to exist in biological systems.
By highlighting key mechanisms that allow living systems to learn and adapt, this special
issue focuses attention on the tunable matter paradigm as an exciting avenue for future research. Papers in this collection take advantage of recent experience garnered from AI and non-biological systems that autonomously acquire desired function, highlighting that this is an
opportune moment for progress. Just as frameworks for describing emergent behavior in non-
tunable matter have driven key advances in condensed matter and materials science, we hope
that this collection will ultimately inspire researchers to develop unifying frameworks for
emergent collective function in living tunable matter that will drive paradigm shifts in the field
of biology.
The Guest Editors
Sadjad Arzash, Syracuse University
Margaret Gardel, University of Chicago
Andrea Liu, University of Pennsylvania
Lisa Manning, Syracuse University
Ed Munro, University of Chicago
Haina Wang, University of Pennsylvania


















