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structure is ultimately held together by a balance
between tension and compression, tensegrity structures,
according to Fuller, are characterized by continuous
tension around localized compression. Does this sound like
any 'body' you know?
'An astonishingly wide variety of natural systems,
including carbon atoms, water molecules, proteins,
viruses, cells, tissues, and even humans and other living
creatures, are constructed using ... tensegrity.' 9 1 All
structures are compromises between stability and mobil-
ity, with savings banks and forts strongly at the stability
end while kites and octopi occupy the mobility end.
Biological structures lie in the middle of this spectrum,
strung between widely varying needs for rigidity and
mobility, which can change from second to second
(Fig 1.49). The efficiency, adaptability, ease of hierarchi-
cal assembly, and sheer beauty of tensegrity structures
would recommend them to anyone wanting to construct
a biological system.
Explaining the motion, interconnection, responsive-
ness and strain patterning of the body without tenseg-
rity is simply incomplete and therefore frustrating. With
tensegrity included as part of our thinking and model-
ing, its compelling architectural logic is leading us to
re-examine our entire approach to how bodies initiate
movement, develop, grow, move, stabilize, respond to
stress, and repair damage.
A
Macrotensegrity: how the body
manages the balance between tension
and compression
There are but two ways to support something in this
physical universe - via tension or compression; brace it
up or hang it up. No structure is utterly based on one
or the other; all structures mix and match these two
forces in varying ways at different times. Tension varies
with compression always at 90°: tense a rope, and its
girth goes into compression; load a column and its girth
tries to spread in tension. Blend these two fundamental
centripetal and centrifugal forces to create complex
bending, shearing, and torsion patterns. A brick wall or
a table on the floor provides an example of those struc-
tures that lean to the compressional side of support
(Fig. 1.50A). Only if you lean into the side of the wall will
the underlying tensional forces be evident. Tensional
support can be seen in a hanging lamp, a bicycle wheel,
or in the moon's suspended orbit (Fig. 1.50B). Only in
the tides on earth can the 90° compressional side of that
invisible tensional gravity wire between the earth and
the moon be observed.
Our own case is simultaneously a little simpler and
more complex: our myofasciae provide a continuous
network of restricting but adjustable tension around the
individual bones and cartilage as well as the incom-
pressible fluid balloons of organs and muscles, which
push out against this restricting tensile membrane. Ulti-
mately, the harder tissues and pressurized bags can be
seen to 'float' within this tensile network, leading us to
the strategy of adjusting the tensional members in order
B
Fig. 1.47 The ancients and Renaissance artists sought a
geometrical ideal for the human form (A), but the modern
equivalent is arising from a consideration of the spatial needs
of the individual cells (B), which could determine a geometric
'ideal' for each body. (A: public domain; B: photo courtesy of
Donald Ingber.)
Snelson - Fig. 1.48A and B). It refers to structures that
maintain their integrity due primarily to a balance of
woven tensile forces continual through the structure as
opposed to leaning on continuous compressive forces
like a stone wall. 'Tensegrity describes a structural rela-
tionship principle in which structural shape is guaran-
teed by the finitely closed, comprehensively continuous,
tensional behaviors of the system and not by the discon-
tinuous and exclusively local compressional member
behaviors.' 9 0
Notice that spiderwebs, trampolines, and cranes, as
wonderful as they are, are anchored to the outside and
are thus not 'finitely closed'. Every moving animal
structure, including our own, must be 'finitely closed',
i.e. independent, and able to hang together whether
standing on your feet, standing on your head, or flying
through the air in a swan dive. Also, although every
45
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