New State of Matter Known as “Disordered Hyperuniformity” Discovered in the Cells in a Chicken’s Eye

February 25, 2014

Science

Researchers Discover New State of Matter

Researchers from Princeton University and Washington University in St. Louis report that the unusual arrangement of cells in a chicken’s eye constitutes the first known biological occurrence of a potentially new state of matter known as “disordered hyperuniformity,” which has been shown to have unique physical properties. These states have a “hidden order” that allows them to behave like crystal and liquid states of matter. They exhibit order over large distances and disorder over small distances. This diagram depicts the spatial distribution of the five types of light-sensitive cells known as cones in the chicken retina. (Courtesy of Joseph Corbo and Timothy Lau, Washington University in St. Louis)

Researchers have discovered the first known biological occurrence of a potentially new state of matter known as “disordered hyperuniformity” in the cells in a chicken’s eye.

Along with eggs, soup and rubber toys, the list of the chicken’s most lasting legacies may eventually include advanced materials such as self-organizing colloids, or optics that can transmit light with the efficiency of a crystal and the flexibility of a liquid.

The unusual arrangement of cells in a chicken’s eye constitutes the first known biological occurrence of a potentially new state of matter known as “disordered hyperuniformity,” according to researchers from Princeton University and Washington University in St. Louis. Research in the past decade has shown that disordered hyperuniform materials have unique properties when it comes to transmitting and controlling light waves, the researchers report in the journal Physical Review E.

States of disordered hyperuniformity behave like crystal and liquid states of matter, exhibiting order over large distances and disorder over small distances. Like crystals, these states greatly suppress variations in the density of particles — as in the individual granules of a substance — across large spatial distances so that the arrangement is highly uniform. At the same time, disordered hyperuniform systems are similar to liquids in that they have the same physical properties in all directions. Combined, these characteristics mean that hyperuniform optical circuits, light detectors and other materials could be controlled to be sensitive or impervious to certain light wavelengths, the researchers report.

“Disordered hyperuniform materials possess a hidden order,” explained co-corresponding author Salvatore Torquato, a Princeton professor of chemistry. It was Torquato who, with Frank Stillinger, a senior scientist in Princeton’s chemistry department, first identified hyperuniformity in a 2003 paper in Physical Review E.

“We’ve since discovered that such physical systems are endowed with exotic physical properties and therefore have novel capabilities,” Torquato said. “The more we learn about these special disordered systems, the more we find that they really should be considered a new distinguishable state of matter.”

The researchers studied the light-sensitive cells known as cones that are in the eyes of chickens and most other birds active in daytime. These birds have four types of cones for color — violet, blue, green and red — and one type for detecting light levels, and each cone type is a different size. The cones are packed into a single epithelial, or tissue, layer called the retina. Yet, they are not arranged in the usual way, the researchers report.

In many creatures’ eyes, visual cells are evenly distributed in an obvious pattern such as the familiar hexagonal compact eyes of insects. In many creatures, the different types of cones are laid out so that they are not near cones of the same type. At first glance, however, the chicken eye appears to have a scattershot of cones distributed in no particular order.

New State of Matter Known as Disordered Hyperuniformity Discovered in Chicken Eyes

Unlike chickens, visual cells are evenly distributed in an obvious pattern in many creatures’ eyes. The Washington University researchers thought the unusual arrangement in chickens (left) had to do with how the cones are packed into their small, thin retina. The Princeton researchers developed a computer-simulation model that mimicked the final arrangement of chicken cones (right). The colored dots represent the centers of the chicken’s eye cells. They are enlarged and colored for visualization purposes. (Courtesy of Salvatore Torquato, Princeton University)

The lab of co-corresponding author Joseph Corbo, an associate professor of pathology and immunology, and genetics at Washington University in St. Louis, studies how the chicken’s unusual visual layout evolved. Thinking that perhaps it had something to do with how the cones are packed into such a small space, Corbo approached Torquato, whose group studies the geometry and dynamics of densely packed objects such as particles.

Torquato then worked with the paper’s first author Yang Jiao, who received his Ph.D. in mechanical and aerospace engineering from Princeton in 2010 and is now an assistant professor of materials science and engineering at Arizona State University. Torquato and Jiao developed a computer-simulation model that went beyond standard packing algorithms to mimic the final arrangement of chicken cones and allowed them to see the underlying method to the madness.

It turned out that each type of cone has an area around it called an “exclusion region” that other cones cannot enter. Cones of the same type shut out each other more than they do unlike cones, and this variant exclusion causes distinctive cone patterns. Each type of cone’s pattern overlays the pattern of another cone so that the formations are intertwined in an organized but disordered way — a kind of uniform disarray. So, while it appeared that the cones were irregularly placed, their distribution was actually uniform over large distances. That’s disordered hyperuniformity, Torquato said.

“Because the cones are of different sizes it’s not easy for the system to go into a crystal or ordered state,” Torquato said. “The system is frustrated from finding what might be the optimal solution, which would be the typical ordered arrangement. While the pattern must be disordered, it must also be as uniform as possible. Thus, disordered hyperuniformity is an excellent solution.”

New State of Matter Known as Disordered Hyperuniformity Discovered

The simulation revealed the underlying pattern of the chicken’s cones. While the arrangement is a type of packing problem, it has the addition of an “exclusion region” around each type of cone that other cones cannot enter. Cones of the same type shut out each other more than they do unlike cones, and this variant exclusion causes distinctive cone patterns. Each type of cone’s pattern overlays the pattern of another cone. So, while it appeared that the cones were irregularly placed, their distribution was actually uniform over large distances. In the diagram above, two cells (left) appear randomly placed. However, the exclusion regions for both the black (center) and red cells (right) push against nearby cells and give the cell arrangements structure. The black cells fall into a triangle-like pattern in the absence of other cell types. (Courtesy of Salvatore Torquato, Princeton University)

The researchers’ findings add a new dimension called multi-hyperuniformity. This means that the elements that make up the arrangement are themselves hyperuniform. While individual cones of the same type appear to be unconnected, they are actually subtly linked by exclusion regions, which they use to self-organize into patterns. Multi-hyperuniformity is crucial for the avian system to evenly sample incoming light, Torquato said. He and his co-authors speculate that this behavior could provide a basis for developing materials that can self-assemble into a disordered hyperuniform state.

“You also can think of each one of these five different visual cones as hyperuniform,” Torquato said. “If I gave you the avian system with these cones and removed the red, it’s still hyperuniform. Now, let’s remove the blue — what remains is still hyperuniform. That’s never been seen in any system, physical or biological. If you had asked me to recreate this arrangement before I saw this data I might have initially said that it would be very difficult to do.”

The discovery of hyperuniformity in a biological system could mean that the state is more common than previously thought, said Remi Dreyfus, a researcher at the Pennsylvania-based Complex Assemblies of Soft Matter lab (COMPASS) co-run by the University of Pennsylvania, the French National Centre for Scientific Research and the French chemical company Solvay. Previously, disordered hyperuniformity had only been observed in specialized physical systems such as liquid helium, simple plasmas and densely packed granules.

“It really looks like this idea of hyperuniformity, which started from a theoretical basis, is extremely general and that we can find them in many places,” said Dreyfus, who is familiar with the research but had no role in it. “I think more and more people will look back at their data and figure out whether there is hyperuniformity or not. They will find this kind of hyperuniformity is more common in many physical and biological systems.”

The findings also provide researchers with a detailed natural model that could be useful in efforts to construct hyperuniform systems and technologies, Dreyfus said. “Nature has found a way to make multi-hyperuniformity,” he said. “Now you can take the cue from what nature has found to create a multi-hyperuniform pattern if you intend to.”

Evolutionarily speaking, the researchers’ results show that nature found a unique workaround to the problem of cramming all those cones into the compact avian eye, Corbo said. The ordered pattern of cells in most other animals’ eyes are thought to be the “optimal” arrangement, and anything less would result in impaired vision. Yet, birds with the arrangement studied here — including chickens — have impeccable vision, Corbo said.

“These findings are significant because they suggest that the arrangement of photoreceptors in the bird, although not perfectly regular, are, in fact, as regular as they can be given the packing constraints in the epithelium,” Corbo said.

“This result indicates that evolution has driven the system to the ‘optimal’ arrangement possible, given these constraints,” he said. “We still know nothing about the cellular and molecular mechanisms that underlie this beautiful and highly organized arrangement in birds. So, future research directions will include efforts to decipher how these patterns develop in the embryo.”

The paper, “Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem,” was published February 24 in Physical Review E. The work was supported by grants from the National Science Foundation (grant no. DMS-1211087), National Cancer Institute (grant no. U54CA143803); the National Institutes of Health (grant nos. EY018826, HG006346 and HG006790); the Human Frontier Science Program; the German Research Foundation (DFG); and the Simons Foundation (grant no. 231015).

Publication: Yang Jiao, et al., “Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem,” 2014, Phys. Rev. E 89, 022721; DOI:10.1103/PhysRevE.89.022721

PDF Copy of the Study: Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem

Source: Morgan Kelly, Office of Communications, Princeton University

Images: Joseph Corbo and Timothy Lau, Washington University in St. Louis; Salvatore Torquato, Princeton University

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8 Responses to “New State of Matter Known as “Disordered Hyperuniformity” Discovered in the Cells in a Chicken’s Eye”

  1. Jim Young Says:

    Yet another miracle of evolution created by the magic of wind, lightning, randomness, and muck! Since there are billions of engineering marvels like this, that means the magic of evolution created a brand new miracle every 2 years or so on average! I could almost worship evolution.

    Reply

  2. Madanagopal.V.C Says:

    An eagle’s eye is telescopic in nature and it can find its prey from high altitude very sharply. Its acuity in vision is marvelous. Its finding prey even in night’s time using ultra-violet light is known. Evolution has given skills depending on the size of the creatures and their needs. Man is standing tall and he need not have an acuity in vision. His needs are confined to a perimeter of small dimension. Smaller the creature,different improvements in vision is needed. Evolution is working marvels in creation, deftly handling physics to play in formation of cornea ,eye lens and retina. Cones are only three in number in humans like Red, Green and Blue, whereas in chicken it is five and crystalline arrangement is also deftly made for its low height and flightless in nature which forbids its distant vision like that of an eagle.The engineering and planning in evolution is simply superb. You get only what you need and nothing more than that for your survival. Thank You.

    Reply

  3. Robert Johnson Says:

    Robert Johnson My chickens display the movements which could be explained by “disordered hyper uniformity” My chooks have the uncanny ability to disappear then reappear at feeding time. I first became suspicious when I found them with Star Trek communicator devises pinned on their breasts! Chickens, like Sheep, seem to operate within the planes of reality proposed by string theory! And are neither wholly in this universe or any other! Further research must be undertaken and reluctantly, being pressed by other commitments I am willing to accept a multi million dollar research grant, along with appropriate staff, chosen from family and friends, and a substantial laboratory facility to study this phenomenon! It is the Governments responsibility to pull their finger out and put their Parsons nose to the grindstone!
    All joking aside I was not aware that chooks had additional color receptors. Is this true of most ground dwelling birds, I understand the reason that evolution would have provided migrating birds and predatory species with extended spectral range!
    I have to feel my way in the dark , yet my cats follow me around with no difficulty
    Now why did evolution not provide me with the ability to navigate in low light situations ? Evolution could not have anticipated that I would have a torch or electric lights?

    Reply

  4. Madanagopal.V.C Says:

    Hello! Johnson! You are not nocturnal in nature, to probe in the darkness like cat. You are supposed to find your food by the day and sleep by the night. I repeat my comment that you will get nothing more than that required for your survival by evolution. If you start using clothes,nature will deplete the hair on your body unlike on animals which stray naked. If you start living in enclosures completely and not in open air, nature will cut down even your scalp hair tremendously. If you don`t use any organ you will lose it. Evolution will help only for your survival and not for your adventures. thank You.

    Reply

  5. Middle-Aged White Man Says:

    “Evolution is working marvels in creation”. So…which is it? Evolution or Creation? Can’t be both. Evolution is the theory that a house built itself with impeccable details and magically somehow adds rooms and technology to itself over time. Creation is the theory that someone had to build the house. I figure houses don’t usually build themselves.

    Reply

    • Free of Superstition Says:

      Watchmaker argument…? I thought that one had been worn out long ago. You’re comparing reproducing systems to non-reproducing systems (biology compared to construction) it’s a false analogy plain and simple.

      Reply

  6. Free of Superstition Says:

    This article’s headline is very misleading, a new state of matter was not discovered in a chickens eye, and this article refutes itself fourteen paragraphs in when they mention liquid helium. Furthermore if anyone cares to look up the study, it does not claim to have discovered a new state of matter.

    Reply

  7. Madanagopal.V.C Says:

    I agree Sir, that houses don`t usually build themselves. But.. the structure of the house and its plan differs through ages. First, humans lived in caves and then in forests under a tree and thatched houses. Don`t you see evolution in stages when the houses are now in skyscrapers. So much so, the life began in simple bacteria with no mouth or exit and only bacterial skin imbibed food particles and exited. This is the simple house primitive in evolution and depending on environment, life became complex and now you are a man with advancement. Except for biblical reasons, creation is just mythological as far as science is concerned. Thank You.

    Reply

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