Nine hours to live in Eden

Mike Sharples experiences the intellectual thrill and moral challenge of cyberbiology

Creatures 2. Mindscape, Pounds 39.95. (online store: www. mindscape.com) +1 800 716 8503. Windows 95/98.

On just a few occasions over the past 20 years I have stumbled across a program that has startled me because it offered a new way of working, or because it fell way outside of what I supposed to be possible on a current computer. I can remember each event clearly: the time I sat at a teletype and conversed with Eliza, a program to simulate a psychotherapist; my first sight of Lunar Lander running on an early graphics computer; a surreal late-night conversation over Arpanet (the forerunner to the Internet) with Parry the paranoid computer; my first trip into the forest of the original Adventure game; the maiden voyage with the Mosaic Web browser.

Playing Creatures was another of those times. I had seen academic demonstrations of artificial life systems and read a paper giving technical details of the program. But the experience of watching an egg hatch into a quasi-sentient pet not only dislocated my view of the steady progress of computing, it was also emotionally disturbing. I caught myself talking to the screen, an activity I associated with arcade addicts and undergraduates left alone too long in the computer lab. I felt an urgent sense of responsibility for my young charge. The instructions had indicated that each creature's babyhood lasts for 15 minutes. In that time I had to learn how to play the game, feed the neonate, keep it out of danger, teach it the ways of the world, and instruct it in basic English. That night, I had my first dream about a computer program. I was trapped in a simulated world where the only way out was to befriend its beings who were simultaneously pixel images and programmers.

I have begun by describing my first encounters with Creatures because to approach the program in any other way would be to miss its point. The developers' brochure states: "Your goal is to raise, teach, nurture and eventually breed these lovable little creatures, whilst protecting them from the hazards of nature. Because they are alive, you must teach them well, otherwise they could fall ill, or even die." Creatures may at first appear to be a twee and somewhat irritating computer game. It is only when you take control and try to bring up a wayward infant that you shift from regarding Creatures as a rather nauseating curiosity and take it on as a personal commitment. A bit like parenthood really.

Creatures is a tour de force of programming and of marketing. It combines multiple interacting organisms possessing brains and body organs with exotic locations and gripping gameplay. It differs from other successful computer games in that the aim is not to kill aliens, but to nurture. One result is that more than 40 per cent of Creatures users are female. The sociable users have formed more than 400 web sites to swap advice.

Creatures 2, just released, offers a rich and beautifully rendered environment that changes with the simulated seasons, containing trees, plants that can seed and flower, and machines such as cable-cars and teleporters. Into this world you bring eggs that rapidly hatch into bipedal humanoid creatures called Norns. Each Norn can move haltingly around its environment and engage with the objects scattered there, such as a ball, a spinning top and a toy car. To allow the Norn to survive for longer than a few minutes you must offer it food from one of the simulated gardens, and then act as its guide and mentor. Whenever the mouse pointer is moved into the game area it is shown as a hand and this acts as a gripper and as the user's presence in the Creatures world. You can shift objects around by picking and dropping them, and attract a creature's attention by waving the hand in front of it. A click on a Norn's nose is interpreted as a tickle, and a click on its rear as a slap. By such means you teach it right from wrong. Learning is not just by crude behavioural reinforcement. A creature can acquire a simple verb-object language. You teach it by typing in object names in its area, and it can learn by operating a simulated teaching machine in its environment or by interacting with other creatures.

As the game progresses a Norn changes shape and displays more mature behaviour, such as the ability to take longer journeys around the environment, and after some nine hours of computer time it dies. It may encounter villains named Grendels that are aggressive and spread disease, and it may engage in types of social behaviour, from playing games to mating.

If Creatures were merely the product of clever programming, imaginative screen design and inspired marketing then it might gain five-star ratings in games magazines and be applauded as a welcome relief from the gothic barbarity of most computer games. But Creatures is also an experiment in artificial life. The life-like behaviour comes not from programming but from an internal structure that is modelled on animal biology. Each Norn has a neural network that controls its sensory-motor coordination and that selects from a range of behaviours and facial expressions. An artificial biochemistry models an energy metabolism including digestion, an immune system, and hormonal regulation of behaviour. A learning mechanism allows the neural network to adapt. The organisation of a creature's brain and aspects of its biochemistry are specified by a variable-length string of binary digits that acts as a genome, divided into individual genes. When two Norns mate the program merges and splices their parental genes to create the genetic makeup of a genuinely original offspring. Random errors can introduce mutations. Some genes code for surface features, such as hair colour, but most specify internal structures, such as chemo-receptors, reactions and brain lobes, rather than derived characteristics such as disease resistance, fearlessness or strength. This gives an unpredictability to inherited behaviour. With more than 550 genes and trillions of possible genetic combinations it leaves plenty of scope for genetic variation and evolution.

A creature also can be exported from the program and emailed to another person's program. As users swap Norns, so the genetic material spreads across machines, increasing genetic diversity and the probability of interesting mutations and emergent behaviour. The current limitation of ten Norns per machine precludes any large-scale social evolution (they are unlikely to evolve a caste system) but the environment is rich enough to offer social behaviour equivalent to a school playground. Norns have already been observed to engage in cooperative play, such as bouncing a ball back and forwards between two individuals.

The developers present Creatures as not only a software toy but a global artificial life experiment, with millions of Norns existing in the cyberspace of users' machines, interbreeding and evolving. But they leave out the corollary. Creatures is also an experiment in the ethics of artificial life. It is being unleashed into a culture fed by amoral and, at times, downright immoral computer games. Unofficial Creatures web sites describe cacogenic experiments, such as people hacking the files containing the Norn's genetic code to introduce mutations. Creatures 2 permits advanced users to mix the code of Norns and the evil Grendels to produce a vicious Norn. If Creatures really is the cradle of a primitive but evolving lifeform, one where a million adolescents may play the role of parent and God, then we should not expect it to remain a charming utopia.

Mike Sharples is Kodak/Royal Academy of Engineering professor of educational technology, University of Birmingham.