Computers are powerful machines to harness artificial evolution to create visual images. To achieve
this we need to design genetic algorithms and evolutionary programs. Evolutionary programs allow
artefacts to be "bred", rather than designing them by hand. Through a process of mutation and
selection, each new generation is increasingly well adapted to the desired "fitness" criteria.
Breed is an example of such software that uses Artificial Evolution to generate detailed
sculptures. The algorithm that we designed is based on two different processes: cell-division
and genetic evolution.
The underlying principle of the Breed morphogenesis is division of cells. One initial cell, a cube,
engenders throughout successive stages of cell division a complex,
multi-cellular "body". Morphogenetic rules determine how the division of a cell occurs, dependent on
its situation between the cells surrounding it. Every potential
situation has a separate rule, so a cell surrounded on all sides by other cells may divide
differently from a cell that only has a neighbour on the left and underneath, or a cell with nothing
at all in the vicinity, etc. Each rule is coded in a gene, and the complete set of rules forms the
genotype of the growth.
A parent cell divides by halving the cubic space that it takes up according to length, width and
depth. This creates eight smaller spaces, each of which either
contain a massive cell or remain empty, according to the rule applicable to the parent cell. The
new cells again function as parent cells during the following division stage. Each division refines
the cells and differentiates the form further, until growth ceases after a number of stages. The
ultimate form, the phenotype, is not specified at a high level in its genotype, but is the result of
the recursive application of simple rules on the lowest organisation level, that of the cell.
The appearance of such a virtual Breed object may take many forms. The majority of these are
comprised of many parts floating separately from each other in space. This is no problem while it
remains a computer model on the screen where gravity does not count, but turned into real material,
subject to gravity, such an incoherent structure would collapse. To automate the search for
constructable results, it is necessary to establish objective and measurable preconditions for
constructability. One crucial condition is that the phenotype should be completely coherent, i.e.
consisting of a single part. The computer can compare two models with each other by counting the
number of separate parts the model contains. The model with fewer parts
satisfies the criterion of "coherence" more, or rather is "fitter" than the model with the higher
number of parts. We are now able to implement a computerised process of trial and error that
incrementally evolves in the direction of potential solutions. The simplest method (two-membered
evolution strategy) is already effective: take a randomly composed genotype as base, generate the
phenotype and test it for fitness; mutate the base genotype, generate the phenotype and test it for
fitness; compare both results with each other, and take the result with the highest fitness as the
new base. Repeat the mutations until the result satisfies the stated requirements.
An initial series of six sculptures was executed manually in plywood. The tracing, sawing and
gluing was a time consuming technique and in any case, we wanted an industrial procedure. It was
not possible to produce such complex forms via computer controlled Rapid Manufacturing techniques
until the end of the nineties. Only with the arrival of the SLS (Selected Laser Sintering)
technology did it become possible to computerise the whole line from design to execution. A second
series of nine samples was realised with this technique in DuraForm nylon. In 2007, a series of
six sculptures is produced with the Printing Metal technique. These objects are made out of stainless
steel, infiltrated with bronze. The results became smaller and more detailed so that the separate
cells of the objects began to be absorbed into the total form.
review Paul Prudence website Data is Nature