Fractal geometry: a design principle for living organisms

ER Weibel - American Journal of Physiology-Lung Cellular …, 1991 - journals.physiology.org
American Journal of Physiology-Lung Cellular and Molecular …, 1991journals.physiology.org
Fractal geometry allows structures to be quantitatively characterized in geometric terms even
if their form is not even or regular, because fractal geometry deals with the geometry of
hierarchies and random processes. The hypothesis is explored that fractal geometry serves
as a design principle in biological organisms. The internal membrane surface of cells, or the
inner lung surface, are difficult to describe in terms of classical geometry, but they are found
to show properties describable by fractal geometry, at least sectionwise and within certain …
Fractal geometry allows structures to be quantitatively characterized in geometric terms even if their form is not even or regular, because fractal geometry deals with the geometry of hierarchies and random processes. The hypothesis is explored that fractal geometry serves as a design principle in biological organisms. The internal membrane surface of cells, or the inner lung surface, are difficult to describe in terms of classical geometry, but they are found to show properties describable by fractal geometry, at least sectionwise and within certain bounds set by deterministic design properties. Concepts of fractal geometry are most useful in characterizing the structure of branching trees, such as those found in pulmonary airways and in blood vessels. This explains how the large internal gas exchange surface of the lung can be homogeneously and efficiently ventilated and perfused at low energetic cost. It is concluded that to consider fractal geometry as a biological design principle is heuristically most productive and provides insights into possibilities of efficient genetic programming of biological form.
American Physiological Society