"As a general principle natural selection is continually trying to
economise every part of the organisation. " That was Charles Darwin,
writing over 100 years ago about e- ciency innature.
Naturalmaterialsareremarkably ef?cient. Byef?cient wemeanthat they ful?l
the complex requirements posed by the way plants and animals function,
and that they do so using as little material as possible. Many of these
requirements are mechanical in nature: the need to support static and
dynamic loads created by the mass of the organism or by wind loading,
the need to store and release elastic energy, the need to ?ex through
large angles, the need to resist buckling and fracture, and to survive
damage. Few optimisation algorithms have been more successful than that
of "survival of the ?ttest". The structural materials of nature
exemplify this op- misation; even today, few man-made materials do
better than those of nature in the function that they ?ll. And of all
the remarkable properties of natural materials, one is truly
exceptional - that of the ability for self-repair. One recurring goal of
material development has been to emulate the materials of nature. Among
these, the most illusive is that of self-repair. In approaching this it
is well to be aware of the nature of the differences that separate the
structural materials of man and those of nature.