How does a spherical robot with 20 legs move?

Amazing stuff!

"... Researchers took inspiration from the symmetry in nature to build a variety of Argus bots with 16 to 22 legs. Each leg had a motor and a camera for seeing a near-360-degree picture of its surroundings, which made the robot capable of moving in any direction without adjustment. Across tests, the team found that more symmetrical robots were more successful on tasks, more energy efficient, and more resilient against injury. A 20-legged Argus, specifically, was especially successful at navigating diverse terrains, self-stabilizing, and responding to mechanical failures. ..."

"Symmetry is a central organizing principle in natural systems, yet its use as a unifying design strategy in robotics has largely remained limited to geometric form.

We show that symmetry can instead be leveraged at the level of dynamic actuation capability. We introduce dynamic symmetry, the uniformity of a robot's attainable center-of-mass accelerations, and formalize it through a measure coined as dynamic isotropy.

Across more than 1,000 simulated morphologies, we found that higher dynamic symmetry consistently improves trajectory tracking, task success, robustness, resiliency, and energy efficiency, with the benefits becoming most pronounced as dynamic isotropy approaches its theoretical limit.

To study this regime systematically, we developed Argus, a family of spherical robots designed to explore the effects of increasing dynamic symmetry.

Members of the Argus family vary in their actuation geometry and dynamic symmetry level, while sharing a common architectural principle: radially oriented linear actuators that directly shape the robot's center-of-mass dynamics. Among them, we build a physical 20-leg Argus variant that achieves near-extreme dynamic isotropy and demonstrates orientation-invariant locomotion, agile traversal of cluttered and deformable terrain, rapid self-stabilization, and resilience to partial actuator failures.

Its distributed sensing further enables omnidirectional perception and object interaction during continuous motion.

These results show that designing robots for symmetry not only in morphology but also in their attainable dynamics provides a powerful and general pathway toward agility, robustness, and multifunctionality in uncertain terrestrial and extraterrestrial environments."

From the abstract:

"Symmetry is a central organizing principle in natural systems, yet its use as a unifying design strategy in robotics has largely remained limited to geometric form.

We show that symmetry can instead be leveraged at the level of dynamic actuation capability. We introduce dynamic symmetry, the uniformity of a robot’s attainable center-of-mass accelerations, and formalize it through a measure coined as dynamic isotropy.

Across more than 1000 simulated morphologies, we found that higher dynamic symmetry consistently improved trajectory tracking, task success, robustness, resiliency, and energy efficiency, with the benefits becoming most pronounced as dynamic isotropy approached its theoretical limit.

To study this regime systematically, we developed Argus, a family of spherical robots designed to explore the effects of increasing dynamic symmetry. Members of the Argus family vary in their actuation geometry and dynamic symmetry level while sharing a common architectural principle: radially oriented linear actuators that directly shape the robot’s center-of-mass dynamics.

Among them, we built a physical 20-leg Argus variant that achieved near-extreme dynamic isotropy and demonstrated orientation-invariant locomotion, agile traversal of cluttered and deformable terrain, rapid self-stabilization, and resilience to partial actuator failures. Its distributed sensing further enabled omnidirectional perception and object interaction during continuous motion.

These results show that designing robots for symmetry not only in morphology but also in their attainable dynamics provides a powerful and general pathway toward agility, robustness, and multifunctionality in uncertain terrestrial and extraterrestrial environments."

ScienceAdviser

Omnidirectional, sea-urchin-like robot defies traditional designs

Extreme Dynamic Symmetry Enables Omnidirectional and Multifunctional Robots (original news release)

Extreme dynamic symmetry enables omnidirectional and multifunctional robots (no public access)

Robots now grow and repair themselves by consuming parts from other machines

Cannibalism among robots (aka open-ended physical adaptation)? Robots are all too human! 😊

"Now, scientists ... have developed robots that can physically “grow,” “heal,” and improve themselves by integrating material from their environment or from other robots. ...

This new paradigm is demonstrated on the Truss Link—a robotic magnet stick inspired by the Geomag toy. A Truss Link is a simple, bar-shaped module equipped with free-form magnetic connectors that can expand, contract, and connect with other modules at various angles, enabling them to form increasingly complex structures. ..."

From the abstract:

"Biological lifeforms can heal, grow, adapt, and reproduce, which are abilities essential for sustained survival and development. In contrast, robots today are primarily monolithic machines with limited ability to self-repair, physically develop, or incorporate material from their environments.

While robot minds rapidly evolve new behaviors through artificial intelligence, their bodies remain closed systems, unable to systematically integrate material to grow or heal.

We argue that open-ended physical adaptation is only possible when robots are designed using a small repertoire of simple modules. This allows machines to mechanically adapt by consuming parts from other machines or their surroundings and shed broken components. We demonstrate this principle on a truss modular robot platform.

We show how robots can grow bigger, faster, and more capable by consuming materials from their environment and other robots. We suggest that machine metabolic processes like those demonstrated here will be an essential part of any sustained future robot ecology."

Robots now grow and repair themselves by consuming parts from other machines

Robots that Grow by Consuming Other Robots (original news release) "Columbia University researchers introduce a process that allows machines to “grow” physically by integrating parts from their surroundings or from other robots, demonstrating a step towards self-sustaining robot ecologies."

Robot metabolism: Toward machines that can grow by consuming other machines (open access)

Fig. 1. Robot metabolism allows machines to “grow.”

Y chromosome found to play key role in making men taller than women

Amazing stuff!

I remember some people (e.g. some feminists) were suggesting that men were inferior to women because of the Y chromosome.

I am not quite convinced by the approach of this study, i.e. the use of abnormal number of chromosomes.

"Height is one of the most evident sex-based differences observed in humans, as men are on an average 13 cm (5 inches) taller than women. Sex hormones certainly play a significant role in driving this dimorphism, but they are not the only factors at play. ..."

From the significance and abstract:

"Significance

Human stature is one of many physical phenotypes that vary between the sexes. On average, adult males are taller than females. However, the underlying biological mechanisms that explain this dimorphism are not entirely understood. Here, we compared heights in three large population-based cohorts that included 1,225 adults with sex chromosome aneuploidies (SCAs). Having an extra Y chromosome conferred a larger increase in height than that observed with an additional X chromosome, independent of male hormonal effects. We conclude that differential expression of height-related pseudoautosomal genes on the X and Y chromosomes contributes to sexual dimorphism for stature. Beyond height, future SCA research may elucidate mechanisms underlying observed sex differences in the prevalence of autoimmune, neuropsychiatric, and other medical disorders.

Abstract

Many human phenotypic traits vary between the sexes, including adult height for which males are, on average, 13 cm taller than females. The biological mechanisms for this sexual dimorphism are not entirely understood.

One hypothesis to explain the sexual dimorphism in height relates to differential expression in males and females of SHOX, a height-related gene in the pseudoautosomal region 1 (PAR1) on the X and Y sex chromosomes. SHOX expression is reduced on the inactive X chromosome (Xi), compared to the active X in females.

Sex chromosome aneuploidies (SCAs), characterized by an atypical number of X and/or Y chromosomes, serve as informative models for investigating PAR1-related gene dosage effects. Here, we leveraged three large biobanks to study 928,605 individuals, including 1,225 adults with SCAs: 45,X (n = 95), 47,XXY (n = 505), 47,XYY (n = 290), and 47,XXX (n = 335).

By modeling height across individuals with various sex chromosome complements, we quantified the contributions of five sex-related genomic contributors to height, including Xi chromosome dosage, Y chromosome dosage, male sex hormones, and effects of Klinefelter and Turner syndromes. We found that a unit increase in Y chromosome dosage confers 3.1cm (95% CI, 1.9 to 4.3) more to height than a unit increase in Xi chromosome dosage, independent of hormonal variables.

The larger increase in height conferred by the Y chromosome explained 22.6% of the observed difference in height between 46,XY males and 46,XX females. This finding is consistent with the hypothesis that reduced SHOX expression in females results in a net difference in height between the sexes."

Y chromosome found to play key role in making men taller than women

X and Y gene dosage effects are primary contributors to human sexual dimorphism: The case of height (open access)

Fig. 1 Height distribution by sex chromosome complement across cohorts.

Mollusk menagerie/family tree from whole genome sequencing of 13 species and detailed genomic analysis of 77 species

Amazing stuff!

The first author, i.e. Zeyuan Chen, of this study works at the Senckenberg Research Institute and Natural History Museum Frankfurt, in my hometown Frankfurt am Main, Germany. 

"... To create an accurate evolutionary ‘tree’ for the phylum, researchers sequenced whole genomes from 13 species, allowing them to look at genetic markers from 77 species in total, including members of every major subgroup of mollusks.

The findings revealed that monoplacophorans were one of the first offshoots of the Conchifera, a group within mollusks that includes almost all the highly recognizable types, including octopuses and their relatives as well as clams and snails.

The analyses also revealed just how genomically diverse mollusks are, with lots of rearrangements and repetitive sequences—features that may have allowed the group’s physical diversity to emerge. ..."

"... In their new study, scientists analysed the genomes of 77 mollusc species, representing all eight major living groups, including lesser-known forms like deep-sea monoplacophorans and worm-like solenogasters. Using cutting-edge genomic techniques, the team reconstructed a detailed evolutionary tree and confirmed key hypotheses about mollusc ancestry. ..."

From the editor's summary and abstract:

"Editor’s summary

Genome sequencing has allowed for a much greater understanding of how species relate to one another than did earlier morphology-based approaches. A particularly difficult phylum to study using genomic data has been mollusks, which encompass species ranging from squid to sea snails, in part due to their high levels of heterozygosity and repetitiveness. Chen et al. sequenced 13 new complete genomes from across the phylum to assemble a new phylogeny for Mollusca. They resolved several highly debated nodes and provide additional genomes for future study of this highly diverse and genomically complex phylum. ...

Abstract

Extreme morphological disparity within Mollusca has long confounded efforts to reconstruct a stable backbone phylogeny for the phylum. Familiar molluscan groups—gastropods, bivalves, and cephalopods—each represent a diverse radiation with myriad morphological, ecological, and behavioral adaptations.

The phylum further encompasses many more unfamiliar experiments in animal body-plan evolution.

In this work, we reconstructed the phylogeny for living Mollusca on the basis of metazoan BUSCO (Benchmarking Universal Single-Copy Orthologs) genes extracted from 77 (13 new) genomes, including multiple members of all eight classes with two high-quality genome assemblies for monoplacophorans. Our analyses confirm a phylogeny proposed from morphology and show widespread genomic variation. The flexibility of the molluscan genome likely explains both historic challenges with their genomes and their evolutionary success."

ScienceAdviser

Cracking the Mollusc Code: Genomes Reveal the Ancient Ancestor of Your Garden Snail (original news release) "An international team of scientists has cracked a longstanding evolutionary mystery surrounding molluscs, one of the most diverse groups of animals on Earth. The groundbreaking research, published today in Science, resolves the family tree for molluscs, bringing long-awaited clarity on their evolutionary history and resolving debates that have persisted for decades."

A genome-based phylogeny for Mollusca is concordant with fossils and morphology (open access)

Nudibranchs like this Flabellina affinis are among the varied forms of mollusks.

Fig. 1. Mollusca timetree.

Challenging the Axon’s Classic Shape

Amazing stuff! Function follows form or vice versa. Could be a breakthrough.

"... Their findings ... contrast with the classical view of tubular axons. ...

“... To see nanoscale structures with standard electron microscopy, we fix and dehydrate the tissues, but freezing them retains their shape — similar to freezing a grape rather than dehydrating it into a raisin,” ...

The researchers studied three types of mouse neurons: ones grown in the lab, those taken from adult mice and those taken from mouse embryos. The neurons were nonmyelinated (they were without the myelin insulating cover that surrounds the axon).

The researchers found the bubbly, pear shape of axons among all of the tens of thousands of images taken of the tissue samples.

The scientists named the pearl-like structures in which the axon swells “non-synaptic varicosities.”

“These findings challenge a century of understanding about axon structure,” ...

The scientists also used mathematical modeling to see if the axon membrane influenced the shape or presence of the pearl on a string structure. They found that simple mechanical models could be used to explain these structures very effectively. ..."

From the abstract:

"Axons are ultrathin membrane cables that are specialized for the conduction of action potentials. Although their diameter is variable along their length, how their morphology is determined is unclear.

Here, we demonstrate that unmyelinated axons of the mouse central nervous system have nonsynaptic, nanoscopic varicosities ~200 nm in diameter repeatedly along their length interspersed with a thin cable ~60 nm in diameter like pearls-on-a-string.

In silico modeling suggests that this axon nanopearling can be explained by membrane mechanical properties.

Treatments disrupting membrane properties, such as hyper- or hypotonic solutions, cholesterol removal and nonmuscle myosin II inhibition, alter axon nanopearling, confirming the role of membrane mechanics in determining axon morphology.

Furthermore, neuronal activity modulates plasma membrane cholesterol concentration, leading to changes in axon nanopearls and causing slowing of action potential conduction velocity. These data reveal that biophysical forces dictate axon morphology and function, and modulation of membrane mechanics likely underlies unmyelinated axonal plasticity."

Challenging the Axon’s Classic Shape | The Scientist "Forget the traditional tubular shape—researchers are investigating a pearl-on-a-string formation for axons, unlocking new insights into neural signaling in health and disease."

Study May Reverse Century-Old Understanding of The Shape of ‘Arms’ on Mammals’ Brain Cells (original news release)

Membrane mechanics dictate axonal pearls-on-a-string morphology and function (open access)

Fig. 1: Axons are pearled, not tubular, under homeostatic conditions.

Fig. 2: Membrane mechanics dictate axon nanopearling.

Soft Body Robots Amputates and Reattaches Its Own Legs

Robot or contortonist?

"... In a new paper, roboticists from The Faboratory at Yale University have given a soft robot the ability to detach and reattach pieces of itself, editing its body morphology when necessary. ..."

From the abstract:

"Biological organisms exhibit phenomenal adaptation through morphology-shifting mechanisms including self-amputation, regeneration, and collective behavior. For example, reptiles, crustaceans, and insects amputate their own appendages in response to threats. Temporary fusion between individuals enables collective behaviors, such as in ants that temporarily fuse to build bridges. The concept of morphological editing often involves the addition and subtraction of mass and can be linked to modular robotics, wherein synthetic body morphology may be revised by rearranging parts. This work describes a reversible cohesive interface made of thermoplastic elastomer that allows for strong attachment and easy detachment of distributed soft robot modules without direct human handling. The reversible joint boasts a modulus similar to materials commonly used in soft robotics, and can thus be distributed throughout soft robot bodies without introducing mechanical incongruities. To demonstrate utility, the reversible joint is implemented in two embodiments: a soft quadruped robot that self-amputates a limb when stuck, and a cluster of three soft-crawling robots that fuse to cross a land gap. This work points toward future robots capable of radical shape-shifting via changes in mass through autotomy and interfusion, as well as highlights the crucial role that interfacial stiffness change plays in autotomizable biological and artificial systems."

Soft Body Robots Amputates and Reattaches Its Own Legs - IEEE Spectrum Inspired by lizards and ants, this robot can change its shape at will

Self-Amputating and Interfusing Machines (no public access)

Shapeshifting organism uses curved crease origami to extend to 30 times its body length

Amazing stuff!

"For the first time, two researchers ... have observed the intricate folding and unfolding of “cellular origami”. Through detailed observations ... discovered helical pleats in the membrane of a single-celled protist, which enable the organism to reversibly extend to over 30 times its own body length. ... the mechanism could inspire a new generation of advanced micro-robots. ..."

From the editor's summary and abstract:

"Editor’s summary

Morphological changes in cellular shape have been studied in the context of cell division, movement through confined spaces, or functionality such as the beating of a heart or digestion within the gut. ... explored the mechanisms that allow for the rapid hyperextension seen in the predatory ciliate Lacrymaria olor, which can extend a neck-like feeding apparatus up to 1.2 millimeters in less than 30 seconds ... Using a combination of live imaging, confocal, and transmission electron microscopy, the authors identified a curved crease origami structure in the subcellular components that enables the rapid shape changes. ...

Structured Abstract

INTRODUCTION

Single-celled protists display a remarkable diversity of forms and accomplish a wide range of functions, including hunting live prey in dynamic environments. Lacrymaria olor, a predatory ciliate, hunts its prey by launching a necklike proboscis that can reversibly extend more than 30 times its original body length in <30 s and perform this task repeatably (more than 20,000 times in its life cycle). Such large-scale morphodynamics—an ability to shapeshift in real time—can be quantified by the large strain and strain rate seen in a single cell. Fundamental limits of morphodynamics and how geometry encodes behavior in single cells remain largely unknown.

RATIONALE

Protists display remarkable strategies to thrive in almost all ecological niches in our planet, from the deep sea to our river streams. Although the relationship between form and function is the bedrock of biological studies, we still have a poor understanding when it comes to explaining the explosive morphological diversity of protists. By applying a lens of geometry, we explored the link between form and function in an iconic, shapeshifting protist, L. olor, which is known to capture prey through the dynamics of an ultralong necklike proboscis. With the advent of various cutting-edge imaging tools, we mapped subcellular components such as the cortical cytoskeleton and membrane architecture of this cell caught in various morphological states, including a contracted and an extended state. Because geometry is scale free, the essential features of the coupled cytoskeletal-membrane architecture can be captured in a scaled-up physical origami model. In this work, we demonstrate how topological singularities in this geometry can control physical transformation of a cell. The deployment of a necklike protrusion through cellular scale origami is one of the largest strain and extension rates observed in a single cell.

RESULTS

We compared largest known strain and strain rates in single-cell morphodynamics and identified L. olor as an outlier. With high-resolution imaging, we discovered that this linear extension is supported by a helical architecture of the cortical cytoskeleton composed of microtubule bands layered in multiple layers forming membrane pleats. This particular geometry stores both membrane and microtubule filaments necessary for rapid deployment of a long proboscis, forming a curved crease origami. The sharp transition between the folded and unfolded state in this curved crease cellular origami is controlled by the presence of two topological singularities: a “d-cone” (developable cone) and a “twist singularity” of the microtubule band. We also built a scaled-up model of this origami to reveal how the coupled dynamics of d-cone and twist traversal leads to the nonaffine nature (spooling) of this deployable origami. Our work reveals how topological singularities can be used by a cell to control deployment of subcellular components and unravels the embodied nature of control of behavior through geometry in this ciliate.

CONCLUSION

As recent studies continue to highlight important ecological roles of protists, it has become critical to understand the origins of complex behavior in these remarkable single cells. Much effort has been put on mapping the genetic diversity of these cells, but we still know very little about the morphological (geometrical) diversity and its function in protists at large. By mapping the subcellular geometry of the cytoskeleton of L. olor, we uncovered geometrical control of extreme morphing behavior in a single cell. As a living example of a microtubule-patterned curved crease origami, our deeper understanding of this structure opens new doors for synthesis of cytoskeleton-based bioengineered materials with transformable characteristics such as deployability. Our work also provides direct inspiration for deployable microrobotics and light-weight space architecture. The blueprints we have been looking for to bring agency and embedded control in microrobotics might be hidden in plain sight in the geometrical diversity of protists."

Shapeshifting organism uses ‘cellular origami’ to extend to 30 times its body length – Physics World

The first example of cellular origami (original news release) Combining a deep curiosity and “recreational biology,” Stanford researchers have discovered how a simple cell produces remarkably complex behavior, all without a nervous system. It’s origami, they say.

Curved crease origami and topological singularities enable hyperextensibility of L. olor (no public access)

Curved crease origami and topological singularities at a cellular scale enable hyper-extensibility of Lacrymaria olor (preprint, open access)

Long-distance predator The remarkable protist Lacrymaria olor with its “neck” extended and retracted.

Fig. 1 Hyper extensible single cells with large strain and strain rates.