The Science of Discworld IV Judgement Da - By Terry Pratchett, Ian Stewart Page 0,79

the system’s potential.

Organic evolution proceeds by invading the adjacent possible. Invasions that fail aren’t invasions at all, and nothing much changes. Successful invasions don’t just change the system that does the invading; they change the adjacent possible of everything. When insects first took to the air, the ones that stayed on the ground were suddenly in danger of predation from above, even though they hadn’t changed at all. Likewise, technology advances by continually invading the adjacent possible. Technological evolution is faster than organic evolution because human minds can use their imaginations to jump into the adjacent possible and see if it works, without actually doing it. They can also copy, which organic evolution does only rarely, aside from reproducing near copies of organisms. These are processes that generate paths and histories, and contexts in which some evolutionary trajectories are viable, but others are not. Only a few select trajectories work. In contrast, thinking in terms of innovations that generate products makes the design process work like magic.

There are a few useful analogies between technological evolution and organic evolution, and a lot of misleading ones. Comparisons between organic evolution and economics abound in the literature, and nearly all of them are misleading, from social Darwinism to the ‘cost’ of reproduction. Some evolutionary trajectories, however, can usefully be compared to biological ones. Examples include telegraph → telephone, especially international with undersea cables as investment, pens → word processors, and rockets → space elevators, which we’ll come to shortly. These changes get rid of old constraints at each subsequent recursion.

There are biological precedents, in which evolution did not lead to increased complexity (as measured by DNA information), but the reverse. One is the evolution of mammals. Mammals have less DNA than their ‘more primitive’ amphibian ancestors, a trick that can be pulled off because mother mammals control the temperature of their developing embryos by keeping them inside their own bodies. Amphibians need huge quantities of genetic instructions to plan for many different contingencies, as their embryos grow in a pond, subject to the unpredictable vagaries of the weather. Mammals dispense with this excess baggage by investing in temperature control.

With the expanding possibilities of the chemical/physical universe as a substrate, and organic evolution as a model for an emergent phase space, we should be asking ‘What are the constraints on technology, if any?’ rather than ‘What is the pattern of technological advance?’ Sometimes there are persistent patterns. Moore’s Law states that computing power doubles every eighteen months. It has worked for decades, even though (indeed, because) technologies have changed dramatically. Some experts think that the increase in power will shortly have to slow down, but others remain convinced that new ideas, often already visible, will keep it going.

Our culture sometimes seems to follow evolutionary trajectories too. As individuals, we respond to the cultures in which we live, and we are conducted into our technological future as it changes progressively. As far as cultures go, this is an evolutionary process. From a human viewpoint, however, such progressive change looks like the development of a more complex living system, a socio-dynamic. Is technology cancerous, born of mutation as it burst out of its hunter-gatherer background, as it evolves into new forms? Or is it developmental, exploiting new organisations as it invents them but maintaining an adaptable but stable path, just like a developing embryo? An embryo destroys many organised structures, and kills many of its cells, as it develops. It builds scaffolding and throws it away when it is no longer needed.

From the point of view of the individual human, caught up in a technological rat race, this stress is clearly a symptom of social pathology, as Alvin Toffler argued in Future Shock. In contrast, looked at culturally, it is natural development. This difference of viewpoint resembles the two ways to describe a thinking mind: nerve cells and consciousness. More generally, not only can every complex system be described in several non-overlapping ways: it can also be described on several levels … as concrete or as a bridge; as an architectural bridge or as a weak point for an enemy invasion.

Human evolution occurs on two levels: embryological development and cultural development. Neither process is preformational, with all necessary ingredients already present. Neither is a straightforward blueprint: make it like this. In both, evolutionary changes occur through complicity between several programmes, each of which affects the future of the others. As time passes, each programme not only affects its own future by its own internal dynamics: it