1. Technology and the Evolution of Complexity
Human Complex Systems, Feb 23, 2007
W. Brian Arthur
External Professor, Santa Fe Institute

2. How does the collective of technology evolve over time?
And what does this say about the evolution of complexity?

3. Consider …
Novel technologies are constructed from existing technologies
… and offer themselves as components—building blocks for the construction of further technologies

4. Technology Builds Itself from Itself
Technology is autopoietic or self-creating:
New elements build from existing ones
Complication builds from simplicity

5. W. F. Ogburn’s Claim (1922)

6. Exponential buildup of technology?
Dubious: Many combinatorics possible
(Simplest gives 2N – N – 1 possible technologies)
Diminishing returns to novelty or to demand possible

7. An Experiment at FXPAL W. Brian Arthur and Wolfgang Polak
Idea
- Create an artificial world in which the technologies are logic circuits
- Give this world “logic needs” to be potentially fulfilled
Allow the system to create technologies to fulfill these
by combining previous technologies

8. Rules of the Experiment
1. Start from one primitive (NAND gate)
2. Make circuits by random combination of existing elements
3. Check to see if any needs (target logic purposes) are fulfilled
4. If so, these novel circuits become new building blocks
5. Better versions (simpler ones) replace previous versions

9. Tech 20

10. 1-bit adder

11. 2-bit adder

12. Tech 33: And-3

13. 3-bit adder

14. 4-bit adder

15. We Find … Quite complicated circuits evolve
An 8-bit adder (16 inputs, 9 outputs) is one of 10177,554 possible circuits

16. We Find … 2. Complicated circuits require intermediate steps
… and intermediate needs
(Cf. R. Lenski et al. Evol. Origin of Complex Features)

17. We Find … 3. Buildup is history dependent
New technologies build on what is

19. We Find …  
4. Sudden appearance of key circuits (enabling technologies) then quick use of these
Full adder appears after 32,000 steps; 2,3,4-bit adders quickly after that

20. Gales of Destruction
When a technology disappears (is replaced) a technology it used may have no further use. That tech then disappears … etc.
Q. Are these gales “sand-pile avalanches”?
I.e. is the system at self-organized criticality?

21. Avalanches of destruction follow a power law

22. Summary: a different view
Technology is a self-constructing “chemistry”
(-cf. genetic regulatory networks)
Technology bootstraps in numbers and complication
Innovation: places of generative interaction important
Where a chemistry is generated, harbored, nurtured

23. The Process as Evolutionary Algorithm
Our algorithm creates a library of functionalities by constructing new objects from previously existing ones
Differs from genetic algorithm or GP in several ways