So far, these principles have not been applied to engineered systems, which are largely linear, optimised, strongly hierarchical, non-competitive, and minimise risk through large safety margins and free energy.

It is curious that we are moving in a direction of creating ever more complex software to perform essentially simple tasks. In contrast, nature does the converse, generating unbelievably complex behaviour from incredibly simple software.

Simple life systems - worms, ants and bees - have been simulated on modest computers, realising the major interactions in nests and communities. Some of this work has now moved to practical application as control software for networks and information agents.

While the underlying software for each entity may be only a few hundred lines of easily understood code, the emergent behaviour of a society of such entities is a another matter. This generally defies prediction and is full of surprises. It might just be that systems of this type cannot be engineered from the standpoint of our established methods and principles. We may have to let go of our long-held desire to define and constrain all the outcomes by specifying, designing and testing systems.

Exponential growth in communication, mobility and information working is creating an increasingly chaotic world.

Taking a leaf out of nature's book, it is clear that we will increasingly need evolutionary systems to meet chaotic demand. Genetics, sex, mutation and progeny spring to mind, but we cannot afford to wait for millions of years of chance mutation. Looking at carbon systems we see a world dominated by one- and two-sex systems.

Two sexes are the most adaptable, complex and intelligent. So we might suppose that sex in software, with the super speed of machines, would suffice. But should we be constrained by nature as to the mechanism and numbers involved, or indeed the nature of the progeny? Probably not. In software there are no constraints whatever - no morality or society.

We might envisage a silicon world where a learnt and positive behaviour is passed on from one generation to another. Progeny by instalments might be a new means of avoiding the evolutionary cul-de-sacs that hamper carbon (when you have evolved into an elephant you cannot backtrack to become a mouse). Progeny by piece parts, many offspring glued together to make the whole, may then provide a solution.

When all of this comes together with noisy decision-making, a subtle blending of random uncertainty and chaos, instead of the full determinism of nailed down logic and software, we may have the right conditions for silicon life.

The question is: are we smart enough to spot artificial life when it spontaneously erupts?

Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is:
http://cochrane.org.uk