May 22, 2005

Automated evolution

A short history of an artificial species, in pictures.

The initial form, once it eliminated all competitors from the primordial pool:

The thing moves by stroking one arm like a paddle against the other arm, while the little fins provide some additional thrust. Longer armed mutants moved much more quickly, and soon took over:

On the other hand, large parts are sexually atractive to these critters, so a sexy mutation began to proliferate:

Of course, sexy and fast is even better:

For a while, things were stable. Occasional efficient-swimming mutations would pop up, but would eventually be eliminated by the dominant form. All this time, the swimming motions got better and better. In particular, the swimbots became much better at turning clockwise, where before they had been much more efficient while turning counter-clockwise.

Then, a sub-population with a different colour managed to establish itself (swimbots prefer to breed with other swimbots of the same colour), and in the process aquired even larger and longer parts than the dominant form:

Up to now, most mutations affected all parts in the same way. A major advance was a swimbot whose head was controlled by different genes than the rest of its parts:

Here's a successful variation that has 4 segments in its arms instead of 3, thin parts for hydrodynamic swimming, and a tiny head. The head thrashes back and forth as the bot swims, so long heads are quite inefficient, as opposed to long arms.

At this point a new, more efficient swimming motion evolved. Instead of sculling one arm as a paddle, it wiggled like a fish. This was slightly slower at the time, but used much less energy. Since the originator was sexy rather than efficient, many of the efficiency traits were lost:

And then, slowly, regained:

With the new swimming motion, many of the fins were proving a drag, so several of them were eliminated:

My current population has been stable for quite some time now, with a good compromise between sexyness and efficiency. Among other things, the fins (now used only for turning) have been made efficient, while the body remains sexy:


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