Artificial life

"Alife" redirects here. For the Italian comune, see Alife, Campania.

This article is about a field of research. For artificially created life forms, see synthetic life. For the mobile games developer, see Artificial Life Inc.

Artificial life (commonly Alife or alife^{[citation needed]}) is a field of study and an associated art form which examine systems related to life, its processes, and its evolution through simulations using computer models, robotics, and biochemistry.^[1] The discipline was named by Christopher Langton, an American computer scientist, in 1986.^[2] There are three main kinds of alife,^[3] named for their approaches: soft,^[4] from software; hard,^[5] from hardware; and wet, from biochemistry. Artificial life imitates traditional biology by trying to recreate biological phenomena.^[6] The term "artificial life" is often used to specifically refer to soft alife.^[7]

A Braitenberg simulation, programmed in breve, an artificial life simulator

Overview

Artificial life studies the logic of living systems in artificial environments. The goal is to study the phenomena of living systems in order to come to an understanding of the complex information processing that defines such systems.

Also sometimes included in the umbrella term Artificial Life are agent based systems which are used to study the emergent properties of societies of agents.

While life is, by definition, alive, artificial life is generally referred to as being confined to a digital environment and existence.

Philosophy

The modeling philosophy of alife strongly differs from traditional modeling, by studying not only “life-as-we-know-it”, but also “life-as-it-might-be”.^[8]

In the first approach, a traditional model of a biological system will focus on capturing its most important parameters. In contrast, an alife modeling approach will generally seek to decipher the most simple and general principles underlying life and implement them in a simulation. The simulation then offers the possibility to analyse new, different life-like systems.

Red'ko proposed to generalize this distinction not just to the modeling of life, but to any process. This led to the more general distinction of "processes-as-we-know-them" and "processes-as-they-could-be" ^[9]

At present, the commonly accepted definition of life does not consider any current alife simulations or softwares to be alive, and they do not constitute part of the evolutionary process of any ecosystem. However, different opinions about artificial life's potential have arisen:

• The strong alife (cf. Strong AI) position states that "life is a process which can be abstracted away from any particular medium" (John von Neumann). Notably, Tom Ray declared that his program Tierra is not simulating life in a computer but synthesizing it.

• The weak alife position denies the possibility of generating a "living process" outside of a chemical solution. Its researchers try instead to simulate life processes to understand the underlying mechanics of biological phenomena.

Organizations

Main article: Artificial life organizations

Software-based - "soft"

Techniques

• Cellular automata were used in the early days of artificial life, and they are still often used for ease of scalability and parallelization. Alife and cellular automata share a closely tied history.

• Neural networks are sometimes used to model the brain of an agent. Although traditionally more of an artificial intelligence technique, neural nets can be important for simulating population dynamics of organisms that can learn. The symbiosis between learning and evolution is central to theories about the development of instincts in organisms with higher neurological complexity, as in, for instance, the Baldwin effect.

Notable simulators

This is a list of artificial life/digital organism simulators, organized by the method of creature definition.

Name	Driven By	Started	Ended
Tierra	executable dna	early 1990s	?
Avida	executable dna	1993	NA
Evolve 4.0	executable dna	1996	2007
Darwinbots	executable dna	2003
Framsticks	executable dna	1996	NA
breve	executable dna	2006	NA
DigiHive	executable dna	2006	2009
TechnoSphere	modules
Creatures	neural net
Noble Ape	neural net
Polyworld	neural net
AnimatLab	neural net	2009
3D Virtual Creature Evolution	neural net		NA

Program-based

Further information: programming game

These contain organisms with a complex DNA language, usually Turing complete. This language is more often in the form of a computer program than actual biological DNA. Assembly derivatives are the most common languages used. Use of cellular automata is common but not required.

Module-based

Individual modules are added to a creature. These modules modify the creature's behaviors and characteristics either directly, by hard coding into the simulation (leg type A increases speed and metabolism), or indirectly, through the emergent interactions between a creature's modules (leg type A moves up and down with a frequency of X, which interacts with other legs to create motion). Generally these are simulators which emphasize user creation and accessibility over mutation and evolution.

Parameter-based

Organisms are generally constructed with pre-defined and fixed behaviors that are controlled by various parameters that mutate. That is, each organism contains a collection of numbers or other finite parameters. Each parameter controls one or several aspects of an organism in a well-defined way.

Neural net–based

These simulations have creatures that learn and grow using neural nets or a close derivative. Emphasis is often, although not always, more on learning than on natural selection.

Hardware-based - "hard"

Further information: Robot

Hardware-based artificial life mainly consist of robots, that is, automatically guided machines, able to do tasks on their own.

Biochemical-based - "wet"

Further information: Synthetic life and Synthetic biology

Biochemical-based life is studied in the field of synthetic biology. It involves e.g. the creation of synthetic DNA. The term "wet" is an extension of the term "wetware".

Related subjects

1. Artificial intelligence has traditionally used a top down approach, while alife generally works from the bottom up.^[10]
2. Artificial chemistry started as a method within the alife community to abstract the processes of chemical reactions.
3. Evolutionary algorithms are a practical application of the weak alife principle applied to optimization problems. Many optimization algorithms have been crafted which borrow from or closely mirror alife techniques. The primary difference lies in explicitly defining the fitness of an agent by its ability to solve a problem, instead of its ability to find food, reproduce, or avoid death.^{[citation needed]} The following is a list of evolutionary algorithms closely related to and used in alife:
   • Ant colony optimization
   • Evolutionary algorithm
   • Genetic algorithm
   • Genetic programming
   • Swarm intelligence
4. Evolutionary art uses techniques and methods from artificial life to create new forms of art.
5. Evolutionary music uses similar techniques, but applied to music instead of visual art.
6. Abiogenesis and the origin of life sometimes employ alife methodologies aswell.

History

Main article: History of artificial life

Criticism

Alife has had a controversial history. John Maynard Smith criticized certain artificial life work in 1994 as "fact-free science".^[11] However, the recent publication of artificial life articles in widely read journals such as Science and Nature is evidence that artificial life techniques are becoming more accepted in the mainstream, at least as a method of studying evolution.^[12]

See also

Systems science portal

• Autonomous foraging
• Artificial life organizations
• Bioethics
• Complex adaptive system
• Darwin machine
• Digital morphogenesis
• Life simulation game
• Mathematical biology
• Player Project
• Simulated reality
• Social simulation
• Soda Constructor
• Synthetic life
• Webots
• Universal Darwinism

References

1. ^ "Dictionary.com definition". http://dictionary.reference.com/browse/artificial%20life. Retrieved 2007-01-19. 
2. ^ The MIT Encyclopedia of the Cognitive Sciences, The MIT Press, p.37. ISBN 978-0262731447
3. ^ Mark A. Bedau (November 2003). "Artificial life: organization, adaptation and complexity from the bottom up" (PDF). TRENDS in Cognitive Sciences. http://www.reed.edu/~mab/publications/papers/BedauTICS03.pdf. Retrieved 2007-01-19. 
4. ^ Maciej Komosinski and Andrew Adamatzky (2009). Artificial Life Models in Software. New York: Springer. ISBN 978-1-84882-284-9. http://www.springer.com/computer/mathematics/book/978-1-84882-284-9. 
5. ^ Andrew Adamatzky and Maciej Komosinski (2009). Artificial Life Models in Hardware. New York: Springer. ISBN 978-1-84882-529-1. http://www.springer.com/computer/hardware/book/978-1-84882-529-1. 
6. ^ Christopher Langton. "What is Artificial Life?". http://zooland.alife.org/. Retrieved 2007-01-19. 
7. ^ John Johnston, (2008) "The Allure of Machinic Life: Cybernetics, Artificial Life, and the New AI", MIT Press
8. ^ See Langton, C. G. 1992. Artificial Life. Addison-Wesley. ., section 1
9. ^ See Red'ko, V. G. 1999. Mathematical Modeling of Evolution. in: F. Heylighen, C. Joslyn and V. Turchin (editors): Principia Cybernetica Web (Principia Cybernetica, Brussels). For the importance of ALife modeling from a cosmic perspective, see also Vidal, C. 2008.The Future of Scientific Simulations: from Artificial Life to Artificial Cosmogenesis. In Death And Anti-Death , ed. Charles Tandy, 6: Thirty Years After Kurt Gödel (1906-1978) p. 285-318. Ria University Press.)
10. ^ "AI Beyond Computer Games". Archived from the original on 2008-07-01. http://web.archive.org/web/20080701040911/http://www.lggwg.com/wolff/aicg99/stern.html. Retrieved 2008-07-04. 
11. ^ Horgan, J. 1995. From Complexity to Perplexity. Scientific American. p107
12. ^ "Evolution experiments with digital organisms". http://myxo.css.msu.edu/cgi-bin/lenski/prefman.pl?group=al. Retrieved 2007-01-19. 

External links

• Computers: Artificial Life at the open directory project
• Computers: Artificial Life Framework
• International Society of Artificial Life
• Artificial Life MIT Press Journal
• The Artificial Life Lab Envirtech Island, Second Life