Artificial life (often abbreviated ALife or A-Life) is a field of study wherein researchers examine
systems related to natural
life
Life is a quality that distinguishes matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes, from that which does not, and is defined by the capacity for Cell growth, growth, reaction to Stimu ...
, its processes, and its evolution, through the use of
simulation
A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the ...
s with
computer models,
robotics
Robotics is an interdisciplinarity, interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist human ...
, and
biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology ...
. The discipline was named by
Christopher Langton, an American theoretical biologist, in 1986. In 1987 Langton organized the first conference on the field, in
Los Alamos, New Mexico. There are three main kinds of alife, named for their approaches: ''soft'', from
software
Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work.
...
; ''hard'', from
hardware; and ''
wet'', from biochemistry. Artificial life researchers study traditional
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditar ...
by trying to recreate aspects of biological phenomena.
Overview
Artificial life studies the fundamental processes of
living system
Living systems are open self-organizing life forms that interact with their environment. These systems are maintained by flows of information, energy and matter.
In the last few decades, some scientists have proposed that a general living systems ...
s in artificial environments in order to gain a deeper understanding of the complex information processing that define such systems. These topics are broad, but often include
evolutionary dynamics,
emergent properties of collective systems,
biomimicry, as well as related issues about the
philosophy of the nature of life and the use of lifelike properties in artistic works.
Philosophy
The modeling philosophy of artificial life strongly differs from traditional modeling by studying not only "life-as-we-know-it" but also "life-as-it-might-be".
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 and different lifelike systems.
Vladimir Georgievich Red'ko proposed to generalize this distinction to the modeling of any process, leading to the more general distinction of "processes-as-we-know-them" and "processes-as-they-could-be".
At present, the commonly accepted
definition of life
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy t ...
does not consider any current alife simulations or
software
Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work.
...
to be alive, and they do not constitute part of the evolutionary process of any
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
. However, different opinions about artificial life's potential have arisen:
* The ''strong alife'' (cf.
Strong AI
Strong artificial intelligence may refer to:
"Strong Artificial Intelligence (AI) is an artificial intelligence that constructs mental abilities, thought processes, and functions that are impersonated from the human brain. It is more of a phil ...
) 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.
Software-based ("soft")
Techniques
*
Cellular automata were used in the early days of artificial life, and are still often used for ease of
scalability and
parallelization. Alife and cellular automata share a closely tied history.
*
Artificial neural networks are sometimes used to model the brain of an agent. Although traditionally more of an
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machine
A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, moveme ...
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.
*
Neuroevolution
Notable simulators
This is a list of artificial life/
digital organism simulators, organized by the method of creature definition.
Program-based
Program-based simulations 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. An organism "lives" when its code is executed, and there are usually various methods allowing
self-replication. Mutations are generally implemented as random changes to the code. Use of
cellular automata is common but not required. Another example could be an
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machine
A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, moveme ...
and
multi-agent system/program.
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 that 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, on learning rather than on natural selection.
Complex systems modeling
Mathematical models of complex systems are of three types:
black-box (phenomenological),
white-box (mechanistic, based on the
first principles) and
grey-box (mixtures of phenomenological and mechanistic models).
[
] In black-box models, the individual-based (mechanistic) mechanisms of a complex dynamic system remain hidden.

Black-box models are completely nonmechanistic. They are phenomenological and ignore a composition and internal structure of a complex system. Due to the non-transparent nature of the model, interactions of subsystems cannot be investigated. In contrast, a white-box model of a complex dynamic system has ‘transparent walls’ and directly shows underlying mechanisms. All events at the micro-, meso- and macro-levels of a dynamic system are directly visible at all stages of a white-box model's evolution. In most cases, mathematical modelers use the heavy black-box mathematical methods, which cannot produce mechanistic models of complex dynamic systems. Grey-box models are intermediate and combine black-box and white-box approaches.

Creation of a white-box model of complex system is associated with the problem of the necessity of an a priori basic knowledge of the modeling subject. The deterministic logical
cellular automata are necessary but not sufficient condition of a white-box model. The second necessary prerequisite of a white-box model is the presence of the physical
ontology
In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality.
Ontology addresses questions like how entities are grouped into categories and which of these entities ...
of the object under study. The white-box modeling represents an automatic hyper-logical inference from the
first principles because it is completely based on the deterministic logic and axiomatic theory of the subject. The purpose of the white-box modeling is to derive from the basic axioms a more detailed, more concrete mechanistic knowledge about the dynamics of the object under study. The necessity to formulate an intrinsic
axiomatic system
In mathematics and logic, an axiomatic system is any set of axioms from which some or all axioms can be used in conjunction to logically derive theorems. A theory is a consistent, relatively-self-contained body of knowledge which usually conta ...
of the subject before creating its white-box model distinguishes the cellular automata models of white-box type from cellular automata models based on arbitrary logical rules. If cellular automata rules have not been formulated from the first principles of the subject, then such a model may have a weak relevance to the real problem.
[
]
Hardware-based ("hard")
Hardware-based artificial life mainly consist of ''robots'', that is, automatically guided machines able to do tasks on their own.
Biochemical-based ("wet")
Biochemical-based life is studied in the field of synthetic biology. It involves research such as the creation of synthetic DNA
In September 2021, Synthetic Genomics Inc. (SGI), a private company located in La Jolla, California, changed its name to Viridos. The company is focused on the field of synthetic biology, especially harnessing photosynthesis with micro algae to ...
. The term "wet" is an extension of the term " wetware". Efforts toward "wet" artificial life focus on engineering live minimal cells from living bacteria '' Mycoplasma laboratorium'' and in building non-living biochemical cell-like systems from scratch.
In May 2019, researchers reported a new milestone in the creation of a new synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to:
Science
* Synthetic chemical or compound, produced by the process of chemical synthesis
* Synthetic o ...
(possibly artificial) form of viable life
Life is a quality that distinguishes matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes, from that which does not, and is defined by the capacity for Cell growth, growth, reaction to Stimu ...
, a variant of the bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
''Escherichia coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
'', by reducing the natural number of 64 codons in the bacterial genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...
to 59 codons instead, in order to encode 20 amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s.
Open problems
;How does life arise from the nonliving?
*Generate a molecular proto-organism in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and ...
.
*Achieve the transition to life in an artificial chemistry An artificial chemistryW. Banzhaf and L. YamamotoArtificial Chemistries MIT Press, 2015.
P. DittrichArtificial chemistry (AC)In A. R. Meyers (ed.), Computational Complexity: Theory, Techniques, and Applications, pp. 185-203, Springer, 2012.P. Dittri ...
in silico.
*Determine whether fundamentally novel living organizations can exist.
*Simulate a unicellular organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms a ...
over its entire life cycle.
*Explain how rules and symbols are generated from physical dynamics in living systems.
;What are the potentials and limits of living systems?
*Determine what is inevitable in the open-ended evolution of life.
*Determine minimal conditions for evolutionary transitions from specific to generic response systems.
*Create a formal framework for synthesizing dynamical hierarchies at all scales.
*Determine the predictability of evolutionary consequences of manipulating organisms and ecosystems.
*Develop a theory of information processing, information flow, and information generation for evolving systems.
;How is life related to mind, machines, and culture?
*Demonstrate the emergence of intelligence and mind in an artificial living system.
*Evaluate the influence of machines on the next major evolutionary transition of life.
*Provide a quantitative model of the interplay between cultural and biological evolution.
*Establish ethical principles for artificial life.
Related subjects
#Agent-based modeling
An agent-based model (ABM) is a computational model for simulating the actions and interactions of autonomous agents (both individual or collective entities such as organizations or groups) in order to understand the behavior of a system and what ...
is used in artificial life and other fields to explore emergence
In philosophy, systems theory, science, and art, emergence occurs when an entity is observed to have properties its parts do not have on their own, properties or behaviors that emerge only when the parts interact in a wider whole.
Emergen ...
in systems.
#Artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machine
A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, moveme ...
has traditionally used a top down
"Top Down" is a song by American hip hop record producer and recording artist Swizz Beatz, included as the eighth track from his debut studio album ''One Man Band Man'' (2007). "Top Down" contains samples of swirls and riotous bursts of 1970s-s ...
approach, while alife generally works from the bottom up.
#Artificial chemistry An artificial chemistryW. Banzhaf and L. YamamotoArtificial Chemistries MIT Press, 2015.
P. DittrichArtificial chemistry (AC)In A. R. Meyers (ed.), Computational Complexity: Theory, Techniques, and Applications, pp. 185-203, Springer, 2012.P. Dittri ...
started as a method within the alife community to abstract the processes of chemical reactions.
#Evolutionary algorithm
In computational intelligence (CI), an evolutionary algorithm (EA) is a subset of evolutionary computation, a generic population-based metaheuristic optimization algorithm. An EA uses mechanisms inspired by biological evolution, such as rep ...
s 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. The following is a list of evolutionary algorithms closely related to and used in alife:
#* Ant colony optimization
#* Bacterial colony optimization
#* Genetic algorithm
#* Genetic programming
#* Swarm intelligence
#Multi-agent system
A multi-agent system (MAS or "self-organized system") is a computerized system composed of multiple interacting intelligent agents.Hu, J.; Bhowmick, P.; Jang, I.; Arvin, F.; Lanzon, A.,A Decentralized Cluster Formation Containment Framework fo ...
– A multi-agent system is a computerized system composed of multiple interacting intelligent agents within an environment.
# Evolutionary art uses techniques and methods from artificial life to create new forms of art.
# Evolutionary music uses similar techniques, but applied to music instead of visual art.
# Abiogenesis and the origin of life sometimes employ alife methodologies as well.
#Quantum artificial life
Quantum artificial life is the application of quantum algorithms with the ability to simulate biological behavior. Quantum computing, Quantum computers offer many potential improvements to processes performed on classical computers, including mach ...
applies quantum algorithms to artificial life systems.
History
Criticism
Alife has had a controversial history. John Maynard Smith criticized certain artificial life work in 1994 as "fact-free science".
See also
References
External links
*
International Society of Artificial Life
''Artificial Life''
journal, at MIT Press Journal
a virtual environment lab
{{Authority control
Simulation