The distribution of cones in a chicken's eye (above) belies a unique and layered hidden architecture.
From left: Joseph Corbo and Timothy Lau, Washington University; Gabor Kecskemeti/Thinkstock
Up
close, many systems look chaotic — clusters of stars, the atoms in
superfluid helium, the haphazard arrangement of certain subatomic
particles. Zoom out, though, and they appear organized. They possess a
“hidden order,” says Salvatore Torquato, a Princeton theoretical
scientist who discovered this phenomenon a decade ago, calling it
“hyperuniform and disordered.”
Recently, neuroscientist Joseph Corbo of Washington
University in St. Louis came to Torquato with a biological puzzle. In
their beady eyes, chickens have five kinds of cones — cells that help
perceive color (humans have three) — tightly packed into a small space.
Corbo wondered why the cells were ordered, but not perfectly ordered.
What was he missing? Together, he and Torquato found, the cones’ tight
arrangement is actually hyperuniform and disordered. “However,” says
Torquato, “it also came with a twist.”
When Torquato looked at just one kind of cone at a time,
he found these, too, had a hyperuniform, disordered arrangement. There
was a hidden order within the hidden order. This “multi-hyperuniform”
and disordered scheme is an arrangement of matter never before seen in
biology. It’s actually an example of evolution bumping up against the
limits of physics: Ideally, the cones would evolve into a perfect
pattern, but without enough room in the eye, they have to do the best
they can.
It also might not be that unique. Corbo believes if we
look a little closer, the eyes of other birds or even other kinds of
animals will reveal a similar multi-hyperuniform structure. (There’s
nothing particularly special about chicken vision, after all.) But
understanding and re-creating the chicken eye’s organizational scheme
could lead to applications for cameras, scanning equipment and other
detectors — machines that, like any biological eye, should pick up some
kinds of light and not others.
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