I‘ve just posted a paper on evolution and the organization of complex systems at E-drexler.com. The paper discusses things like factories, paint, and conjoined twins to illustrate four crucial differences between machine-like and life-like systems.
As an update, I added a preface that outlines the thesis of the paper and explains why the title (“Biological and Nanomechanical Systems: Contrasts in Evolutionary Capacity”) is somewhat misleading — the topic is far more broad than that, and addresses fundamental questions about the relationship between evolution and how systems are organized.
Here’s the preface:
Biological and Nanomechanical Systems: Contrasts in Evolutionary Capacity
Despite its title, the paper that follows [posted here] is best read, not as discussion of nanomechanical systems, but as an exploration of broad and fundamental questions about the contrasts between biological organisms and machine-like systems of all kinds. It describes and analyzes the consequences of a pattern of profound differences between the products of design and the products of evolution, a pattern that is directly linked to their enormous and fundamental difference in evolvability. The reason for these differences explains why members of vast class of machine-like systems could never evolve, whether or not some of those systems would have potential functional advantages relative to the products of biological evolution.
The basic argument is as follows:
- Evolvable systems must be able, with some regularity, to tolerate (and occasionally benefit from) significant, incremental uncoordinated structural changes. This is a stringent contraint because, in an evolutionary context, “tolerate” means that they must function — and remain competitive — after each such change.
- Biological systems must satify this condition, and how they do so has pervasive and sometimes surprising consequences for how they are organized and how they develop.
- Designed systems need not (and generally do not) satify this condition, and this permits them to change more freely (evolving in a non-biological sense), through design. In a design process, structural changes can be widespread and coordinated, and intermediate designs can be fertile as concepts, even if they do not work well as physical systems.
In reading the paper, please keep in mind the obsolescence (since 1992!) of my initial, 1986 suggestion of using small self-replicating systems as a basis for high-throughput atomically precise manufacturing. There are better ways to do the job, and it is perhaps unsurprising that factory-style systems are superior.
Thinking about machines in the context of self-replication did, however, draw my attention to deeper questions about the organization of biological systems, and why they are have so little resemblance to the products of intelligent designers. This paper is the result, and nanotechnology is almost beside the point.
The conclusions of this paper are relevant to current concepts of advanced nanotechnology chiefly because they explain what otherwise might seem mysterious: that systems entirely unlike living cells can, by several engineering metrics, implement better ways to perform atomically precise fabrication.
Drexler, K. E. (1989). “Biological and nanomechanical systems:
Contrasts in evolutionary complexity”, In C. G. Langton (Ed.),
Artificial Life (pp. 501-519). Redwood City, CA: Addison-Wesley
See the paper here:
“Biological and Nanomechanical Systems:
Contrasts in Evolutionary Capacity”
If you have a taste for abstractions at this level, see also:
- The Antiparallel Structures of Science and Engineering
- Science and Engineering: A Layer-Cake of Inquiry and Design
- Exploratory Engineering:
Applying the predictive power of science
to future technologies