Key aspects of life
This is about important aspects of life that I think have not been widely
recognised.
Among the features that distinguish life from non-life the most important
seem to be the uses of information by living organisms and parts of
organisms during interactions with parts of the environment and also during
internal processes of reproduction and development some of which lead
to evolution of new forms of life.
Information is used both by whole organisms and also by parts of organisms when those parts determine which actions are possible for them and somehow select possibilities to realise.
That raises questions such as:
What is information?
What mechanisms are available to various organisms, or parts of organisms,
or collections of organisms, for acquiring and using information?
How did those mechanisms evolve during the history of the species and its
evolutionary precursors?
More specifically: How did mechanisms evolve enabling sharing information with
conspecifics for various purposes, including initiation and control of
coordinated actions, such as capturing prey, creation and manipulation of
various objects such as tools, shelters, weapons, and later also creation of
information stores?
A less obvious question: How did mechanisms evolve that enable different parts of organisms to acquire, use and share information with other parts? Such mechanisms need to use information to enable them to perform their functions, for instance when one body part detects a need to perform some action or actions (including stimulating, or suppressing or modifying processes in other body parts)?
Additional forms of (partial) information-sharing occur during sexual
reproduction, whose mechanisms combine parts of male and female genomes to
create a new individual with a new, possibly unique at that time, genome.
Such mechanisms were discussed in depth by Tibor Ganti, in his book
The Principles of Life,
(Translation of the 1971 Hungarian edition),
Eds. E. Szathmáry, & J. Griesemer, OUP, New York.
That book presents Ganti's "Chemoton" theory, specifying requirements for the
earliest single-celled organisms capable of sexual reproduction. The ideas are
complex and I don't claim to have understood all of the details. However, the
complexity of the ideas reflects the complexity of the biochemical mechanisms
and processes that make life, in all its complexity and variety, possible.
There is a useful summary/review of Ganti's work by Gert Korthof, who also
provides a large collection of related references:
https://wasdarwinwrong.com/korthof66.htm
Another tribute to Ganti:
https://www.chemoton.com/index.php.en
Click on the Union-Jack flag in small rectangular box to get the English
version.
In all these contexts, use of information requires physical mechanisms for capturing, encoding, storing and manipulating information, which can then be used in performing various functions, including, for example, using information to decide when and how to initiate, modify or terminate some information-using process!
Below I attempt to provide (in some cases partial) answers to questions about what information is used in living organisms, when it is used, how it is used, what the consequences of its use are and how the required mechanisms evolved in the species and develop in the individual, a task which, of course, requires information processing by me, and as such may include gaps and errors.
Some background information:
-
A useful history of debates and theories about the origins of language,
including the possibility that sign languages preceded spoken languages, is
available on Wikipedia:
https://en.wikipedia.org/wiki/Origin_of_language,
-
Evidence that when deaf children without any form of linguistic
communication abilities are brought together they are able to create
their own new sign language, used for sharing information, asking and
answering questions, and coordinating actions, as happened in Nicaragua, is
presented in this BBC documentary (and several other online sources):
https://www.bbc.co.uk/news/av/stories-51372265
- That suggests that the human genome provides powerful mechanisms related to processing of information, including mechanisms for creating, sharing and using languages of many kinds, including sign languages and spoken languages.
- I conjecture that the mechanisms for using sign languages evolved first and mechanisms for using spoken languages evolved later, requiring new genetic mechanisms that created complex links between breathing mechanisms, e.g. lungs and nose, and eating mechanisms, e.g. mouth, tongue, teeth, lips, and new swallowing mechanisms used for transmitting liquids and chewed food to the digestive system, via the esophagus and stomach.
All this raises the question: "What is information?"
I am not using "information" in the narrow technical sense, measured by
numbers of bits in bit-patterns, introduced by Claude Shannon while working
for his employer, the Bell Telephone Company, but in the much older sense of
"information", used, for example, by Jane Austen in her novels a century
earlier, in episodes where her characters use newly acquired information to
change plans, take decisions and perform actions. Her characters also
communicate information to other individuals, both intentionally and
unintentionally, e.g. when observed by other individuals.
Shannon was not confused, but many of his admirers were confused, and as a result many of them thought and wrote mistakenly about information items as having a number of bits, providing a numerical measure of amount of information. I don't think there is any general purpose measure of amount of information acquired, used, or transmitted although amounts may be partially ordered, e.g. when some or all of one information package is included in or overlaps with another.
Comparisons of (non-numerical) amounts of information in other contexts, where there is no overlap, is also possible, e.g. comparing the amount of information specifying growth of a patch of grass with the amount of information required to specify the production of an animal, such as a chicken, or an elephant. It seems to be intuitively obvious which requires more information, but I shall not now attempt to provide a justification for that intuition. I welcome suggestions!
Information formats and media
Humans can communicate information in many different formats using many
different physical media, and throughout history have developed new
formats and mechanisms for communicating, storing, or using information, long
before bit-patterns came into general use in the 20th century. (There is
evidence that binary representations of numbers had previously been invented
in ancient times. Information about this can be found on Wikipedia.)
Origins of new forms of life
Are all forms of life derived from pre-existing forms of life, or can some
(primitive?) life forms emerge from inorganic processes? According to
evidence reported in Wikipedia, some life forms have only non-living
precursors:
https://en.wikipedia.org/wiki/Earliest_known_life_forms
The evolution of new organisms may include creation of new forms of information and new species-specific information processing mechanisms, including new forms of information used during during reproduction and development of members of the new species as well as new forms used at later stages.
Behaviours of living systems, and also the mechanisms of reproduction, development, and growth of living systems, make use of information, and were not designed by humans or by machines designed by humans or other living systems.
So the naturally occurring information-using mechanisms in living systems were not designed by living systems! The phrase "naturally occurring" rules out brain implants and other devices developed by humans and inserted into humans and other organisms.
Distinctive features of living matter
Are the requirements for describing or explaining aspects of life, or of
living organisms, significantly different from those that suffice for
non-living matter? I think the answer is "yes", but I don't yet have precise,
well thought out, detailed answers. The following is an "early-draft" attempt
to formulate at least a partial elaboration of the differences between living
and non-living matter.
A potential source of confusion is that over many centuries, human thinkers, including researchers in the physical sciences, have developed notations, and operations on notations, for describing portions of matter, the properties they can have, the space they occupy, the relationships that can exist, the processes that can occur (which change properties, relationships, and space occupancy) and the types of causation involving forces of various kinds that can produce or prevent or modify changes in properties and relationships. These successes make it tempting to think that the same modes of thinking will suffice for attempts to understand living systems.
However, the resources used (by humans) for thinking about non-living matter have changed over time, for example after discovery of forms of magnetism, and differences in electrical properties of different kinds of matter, and when theories of gravitational attraction were developed.
Those new ways of thinking about non-living systems included use of increasingly complex forms of numerical/arithmetical notations for structures, properties, relationships and processes, combined with increasingly complex logical notations, leading to many important advances in understanding and explaining natural phenomena and phenomena discovered or produced in scientific laboratories and engineering processes, and also used in asking new scientific questions and proposing answers.
Many researchers who are familiar with those successful modes of description of non-living systems (unthinkingly?) assume that the same resources suffice for asking and answering questions about living organisms.
However, ways of thinking about non-living systems are inadequate for thinking
about many of the facts about biological phenomena, including hatching
processes in eggs, and the amazing physiological and behavioural changes that
occur in insect metamorphosis. Those facts indicate that we need significant
extensions to our ways of thinking and reasoning about what sorts of things
can exist or happen in this universe and how we can describe and formulate
explanatory theories about them.
In particular, we need a richer/deeper understanding of how living systems
make use of information, to build new explanatory and predictive
theories, for instance when our ancestors who tried to explain apparent
motions of "heavenly" bodies coming up from the horizon in one direction and
disappearing below the horizon in another direction produced evidentially
supported but mistaken theories about what seemed to be obviously going on.
Later, discovery of new evidence showed a need to revise the theories.
Correcting those mistakes required development of new apparatus for thinking
about space and time and our location in space, and the mechanisms and
relationships that produced the convincing, but misleading, evidence that sun,
moon, and stars moved around our ancestors.
The human genome proved rich enough to be capable of producing better, more
accurate, theories, postulating that humans were on a planet that moved
around the sun, while the moon moved around the earth. But that took a
long time, and also required production of some entirely new hypotheses about
features of the universe, including the theory of gravitational attraction.
It also required development of new mathematical theories and techniques, to
allow consequences to be derived, including prediction of results of
new observations and experiments.
All of that depended not only on features of the genome, but also on features
of the biochemistry that enabled gene-expression processes to use biochemistry
to repeatedly extend the genome in ways that produced new competences in
processes of gene expression, leading to continuing development of
increasingly powerful technologies and increasingly powerful
predictive/explanatory scientific theories.
Some of the details of those evolutionary and developmental processes are
described in this (very long and still growing) document:
IS THERE A BETTER WAY TO EXPRESS ALL THIS???
The importance of information for living organisms
Information is also passed to later generations via evolved mechanisms for
creating, using, storing, and transmitting information both about species
specific designs for body parts and information about items to be expected in
the environment.
The information is not encoded in bit patterns, but in more complex mostly
species-specific patterns of chemical structures used to control reproductive
and developmental processes.
Can non-living entities use information?
However, some naturally occuring processes can produce results that extend the
processes that can occur, for instance when a rock falling on an unstable
configuration of rocks causes more rocks to fall, or when a geological process
makes new geological processes possible. But those processes do not use
information, although they use matter, energy, forces, and spatial
relationships.
Uses of information by human-designed machines
But no human-designed machines come close to replicating the achievements of
biochemical disassembly and reassembly processes that occur in living systems,
such as processes that produce new vertebrate organisms in eggs (e.g. birds,
lizards, snakes, turtles), and processes in cocoons that transform previously
hatched insects into very different insects with very different behaviours.
Moreover, human-designed machines, and machines designed by human-designed
machines occupy larger, usually much larger spaces, and use far more
physical matter and far more energy than the developmental, reproductive and
metamorphosis processes in living organisms. Nothing designed by human
engineers (or by products of human engineering) comes close to being able to
perform physical and behavioural transformations similar to the changes
produced during insect metamorphosis in a cocoon, changes that occur without
using temperatures pressures or forces that could harm living matter.
Compare that with the energy requirements, forces used, and physical speeds of
particles in laboratories designed by physicists to investigate fundamental
properties of physical matter, e.g. using linear or circular particle
accelerators. Can any such physicists, or future physicists, design and build
machines that can transform the physiological structures and behavioural
competences of insects in predictable ways without damaging the abilities of
the insects to find and consume nutrients and to mate with other members of
the species, as happens during insect metamorphosis? I suspect that
this will forever be impossible for human designed machines. Future exceptions
may perhaps be organisms bred by humans from naturally occurring organisms!
The above facts suggest the following conclusions
These processes use much smaller ranges of temperatures and physical sizes of
mechanisms than machines designed by humans (or by machines designed by
humans) to create machines that perform actions on physical objects controlled
by programs encoded in bit-patterns. For example, no human-designed assembly
mechanism can operate in a space as small as an insect cocoon, using a small
range of temperatures and pressures similar to those occurring in cocoons.
A key feature of such forms of life (unlike complex geological processes such
as continent formation, avalanches and formation and development of tornadoes)
is use of information about what already exists (internally and
externally) and about what could possibly exist (internally and externally) to
influence selection of actions to change what exists both internally, e.g.
through growth and repair, and externally by changing the environment. For
example, tornadoes and geological formation processes do not use information
to decide where to travel, what to do, how to do it, how to avoid obstacles,
etc.
Often the information about what works is not explicitly represented in living
organisms, but is implicit in the history of ancestors of the organisms, some
of whom had descendents that had produced alternative structural changes that
prevented further replication for some reason (e.g. inability to cope with
predators or climate change) while others had descendents with changes that
improved abilities to survive and produce new replicas of themselves, by using
new information to guide selection of options and influence details of
resulting physical processes.
There are some non-living mechanisms created by humans (or by machines created
by humans) that share some aspects of life, e.g. the internet, but nothing
with the full richness/complexity of living organisms. Moreover human-created
machines designed to have some of the behavioural capabilities of animals
typically occupy much larger spaces and use far more energy to produce their
behaviours than the animals that inspired their design. No machine created by
humans has the behavioural competences of a squirrel or a monkey, while
occupying as little space as a squirrel or a monkey.
I doubt that humans will ever be able to create machines that can mimic a
monkey or ape able to move through tree-tops feeding on fruit while carrying
an infant!
It is possible that the above specification for life in terms of use of
information is too broad, e.g. if there are geological or atmospheric
processes that meet that specification, though I think that is unlikely. For
example, tornadoes, avalanches, geological mechanisms of continental drift,
mechanisms of delta formation etc., do not make use of information to make
choices between options! The same is true of larger scale physical
transformations such as formation of new planets or galaxies. Could there be a
galaxy that uses information to decide what to do next?
There may be unnoticed flaws in my account of living things and components of
living things as information users, so I welcome suggestions for corrections,
for additional content or improved presentation.
An important feature of forms of life and biological mechanisms discussed here
is that there can be comparisons of size, or of amount, based on subset
relations, that do not require any use of numerical measurement. So the fact
that the contents of one organism or physiological structure is completely
contained in another, and is therefore smaller, does not imply that those
contents have numerical measures that can be compared.
I am grateful to Gordana Dodig-Crnkovic for comments sent to me and for her
online papers and presentations, including
Many such examples are already included in the evol-devol web site mentioned
above, including examples of what might be called "sub-organism
biointelligence", but I am sure there are also many missing items.
My ideas about life and information were strongly influenced by the work of
Lynn Margulis, referenced in the evol-devol web site.
WARNING
In the past, it seemed to be obviously true that the sun, the moon, and
stars move around us, like clouds, but further away. So ancient thinkers
mistakenly searched for causes of those movements. I suspect there are still
humans on this planet living away from modern communication technology and
educational systems, who still hold some of the old mistaken beliefs about the
sun our moon and other visible distant entities.
I also suspect that much published research in psychology and neuroscience
referring to information processing mechanisms will turn out to be seriously
mistaken, because it ignores chemistry-based information processing in
synapses.
My thoughts reported here were originally triggered by hearing Professor Seth
Grant (University of Edinburgh) comparing the complexity of
information-processing powers of synapses with the powers of the internet, at
a conference in 2008, and strongly challenging then popular theories about the
roles of neurons and synapses in brains. For more information about him search
for his name in this document:
https://cogaffarchive.org/evol-devol.html
Some of my ideas were also inspired by Schrödinger's little book
What is life?, partly transcribed with comments here
There may also be connections with the work of Gregory Bateson whose work I
discussed in a document written several years ago, now available here:
It is possible that I shall later think of more ways in which non-living
entities producing complex behaviours differ from living entities with powers
that are similar in complexity. If so, I'll update this note.
https://cogaffarchive.org/evol-devol.html.
which includes a link to this complex and messy diagram (based on a
suggestion by Susan Stepney (York University, UK):
As stated earlier, in living entities, mechanisms of interaction with the
environment and mechanisms of growth, development, repair and replication not
only use physical substances and mechanisms, but also use
information, e.g. to consider alternative possibilities, and make
selections between alternatives.
Naturally occurring non-living entities, such as continents, volcanoes,
thunderstorms and tornadoes, can undergo and produce changes of structure and
behaviour of matter that in some ways resemble changes during evolution and
development of living organisms, but those non-living examples do not
consider options and then decide what to do, so they have no need to use
information about possibilities for changing or extending either their
environments or their internal physiological structures, and they are
therefore not able to choose between those possibilities on the basis of
needs and preferences.
In contrast with such naturally occurring non-living entities there
are now many human-designed non-living machines that do collect
information and use that information in considering and making decisions about
which actions to perform, internally or externally.
Tentative answer to "What are distinctive features of life?"
Life exists on or in a physical/chemical entity (e.g. galaxy, or planet)
containing naturally occurring (e.g. not designed and created by
humans or other animals) components that are able to extend and replicate
themselves using mechanisms that repeatedly add new forms of complexity by
absorbing matter from their environment, decomposing and recombining
components of both newly absorbed and previously stored matter, and creating
slightly modified replicas of themselves or extensions of themselves (e.g. in
spreading plants such as grass), using mechanisms that allow the replication
processes to produce new variations in structures and functions, including new
replication mechanisms!
Of course, not all living organisms have such abilities, e.g. trees and
grasses do not.
Questions, comments, suggestions, and criticisms can be sent to me at the
email address below.
The ideas presented here are closely related to the theory of meta-configured
genomes developed in collaboration with Jackie Chappell, who first noticed the
relevant empirical facts while doing research on New Caledonian crows for her
Oxford DPhil thesis. We later extended her ideas after she came to the
University of Birmingham and began to collaborate. An introduction to our
ideas about meta-configured genomes is available in the video available here
(relocated from the original University of Birmingham website, which is no
longer accessible, so some of the links to related work will be broken):
https://cogaffarchive.org/movies/meta-config/
https://conf.researchr.org/details/models-2023/models-2023-models/5/Navigating-the-White-Water-World-with-Digital-Humanism
I am not suggesting that she agrees with my conjectures, though she finds them
worth discussing. If appropriate, I'll add here any criticisms or comments on
this document, if she sends me any!
Author: Aaron Sloman
Old URL, which no longer works:
https://www.cs.bham.ac.uk/~axs
Emeritus/Honorary Professor of Artificial Intelligence and Cognitive Science.
School of Computer Science
University of Birmingham, UK
UNIVERSITY EMAIL ADDRESS: a.sloman-At-bham-ac-uk
In case email to the above address fails, comments and questions may be
sent to my blueyonder (home) email address:
aaron dot sloman at blueyonder.co.uk.
No longer functioning email address:
There is an email address for me that no longer works: a.sloman@cs.bham.ac.uk.
Messages sent there will receive no replies. I have not been able to access
messages sent there since early 2024. Anyone reading this who has written to
me without getting a reply can re-send the message to the address without
'cs.'. However, keeping up with email is always a problem!
Unfortunately many URLs and email addresses have been "broken" by (in my view
disastrous) changes at the University of Birmingham, UK!
BACKGROUND NOTE
MISSING HISTORY OF EVOLUTION ON EARTH
Although much research has been done on the evolutionary histories of a huge
variety of forms of life on this planet, investigating changes in their
physiological structures, habitats and behaviours, there is an even
richer, much longer, history, nowhere completely summarised, which is the
history of all the many types of biological mechanisms,
substances, and processes that have existed on this planet since the
earliest life or proto-life forms were produced, and the roles those
(sub-organism) mechanisms and their products have had in the species in which
they occurred, in some cases with impacts on other species, such as predators
and prey of the species directly affected.
HUMAN HISTORY SHOWS THAT WHAT SEEMS TO BE OBVIOUSLY TRUE CAN TURN OUT TO BE
SERIOUSLY MISTAKEN
https://cogaffarchive.org/misc/s/schrodinger-life.html
https://cogaffarchive.org/misc/information-difference.html
With title:
What did Bateson mean when he wrote
"information" is "a difference that makes a difference"?
In which I note that the claim often attributed to him is not what he
actually wrote, namely that "a bit of information is a difference that makes a
difference", later revised as "the elementary unit of information" is "a
difference that makes a difference". But my general conclusion was that
Bateson's claim is relevant only to very simple information items, unlike, for
example, the information in the sentence "There are infinitely many prime
numbers".
Creative Commons Licence
This work, and everything else on my website, unless explicitly excluded, is
licensed under a
Creative Commons Attribution 4.0 License.
If you use or comment on my ideas please include this URL if possible
so that readers can look at the latest version:
https://cogaffarchive.org/misc/whatlife.html
Almost everything I write is later updated. Unfortunately standard modes of
publication do not support this.
Maintained by
Aaron Sloman
School of Computer Science
The University of Birmingham
