Greater Diversity through Evolutionary Algorithms

Recently I read a rather interesting article from a Scientific American blog which hypothesizes about the shape of the human penis from an evolutionary standpoint.

[The methodology employed is described as  “logico-deductive investigative” — meaning that the penis current form is studied within the context of its function and hypothesis are formed, working backwards, regarding why this form came about. I imagine that this is the most natural methodology an evolutionary biologist or psychologist might employ. Understanding this and other methods of explaining evolutionary design might be an interesting exploration for some future post. ]

In a follow-up interview, the researcher Gordon Gallup emphasizes that evolution occurs by selection, not by design. “The raw material for such selection consists of nothing more than random genetic accidents (mutations).” As such, two separate genetic branches cannot be expected to follow the same path of optimization, even if starting with identical initial parameters. This is, of course, very fortunate, for it leads to the great diversity of life where so many radically different methods are employed to solve the same universal problems of survival. 

In contrast, the  solutions reached by purposeful human design are far more limited in diversity. A student of architecture, for example,  might be struck by the number of radically different approaches that humans have employed. 



This range of designs, however, is determined solely by human creativity and contrained by cultural, religious, and other influences. Augmenting human creativity with evolutionary computations could result in an explosion of design ideas.

While one might hesitate to accept that computers could so directly contribute to the creation of art, and before we dive in protest into philosophy and aesthetics, allow me to point out that 

  1. computers and electronic media are already an important contributor to art today, and all that is being suggested is an additional computer-based tool in artistic exploration
  2. we find diversity in nature beautiful, and there is no great difference between natural selection and a hypothetical evolutionary algorithm on a computer.

Architecture’s easily recognizable combination of engineering and art makes it a convenient example. The idea that the increased use of evolutionary methods could lead to a dramatically greater diversity of solutions, however, extends well beyond architecture to many other disciplines, both scientific and creative.

May 10, 2009. Tags: , , , , . Emergence. Leave a comment.

Aggregates, Crystals and a simple algorithm to explore.

A particle randomly floats through space eventually encountering a stationary ‘seed’. The two stick together and form a cluster that grows and grows as more randomly floating particles encounter it and attach themselves.  This is a simple algorithm, and it is actually quite provocative.

Simple Fractal created using the described method.

Simple Fractal created using the described method.

Known as diffusion limited aggregation (DLA), the process produces clusters like the ones in the above images. The clusters are called Brownian Trees and are fractal with a dimensionality of about 1.7.  They were the inspiration for all sorts of computer art in and since the 90s (see Paul Bourke’s work and images — if you try his software, let me know what you think of it). 

Coral Growth Pattern

Coral Growth Pattern

DLA simulates several types of natural processes. Paul Bourke notes that zinc particles in an electrolytic solution wander around aimlessly before attaching themselves to electrodes. More familiar might be the path taken by electricity in a lightning bolt (using a plane instead of a point as the attractor) or in those plasma globes you can find at stores like Spencer’s Gifts (using a spherical attractor).  

Aggregation of the soot produced in the combustion of motor fuels reduces the performance of the engine, and the network structures they produce are DLA-based. …and so on — the world is full of DLA.

A seed is often carefully chosen to reduce randomness in the controlled growth of crystals, but a seed is also that piece of dirt on your window on a cold cold day that serves as an attractor for the frost that begins to form. And this frost can be so very beautiful.

When I came down to breakfast, two of the windows were almost opaque and the others were etched with graceful, fernlike sprays of ice which looked rather like the impressions left in rocks by some of the antediluvian plants, and they were almost as beautiful as anything which the living can achieve. Nothing else which has never lived looks so much as though it were actually informed with life.  
— Joseph Wood Krutch, “The Colloid and the Crystal.”

Diffusion Limited Aggregation is a very simple algorithm to describe and to visualize.  As a simulation for countless natural phenomenon, it has applications in science and in engineering. It is beautiful to look at, and with small variations yields even more interesting results. It is algorithms like these that inspire us to explore of the world of algorithms.

February 18, 2009. Tags: , , , , , . Chaos, Emergence. 2 comments.