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 decide which possibilities to select.
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 for 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?
Less obviously, how did mechanisms evolve that enable different parts of organisms to acquire, use and share information with other parts? Did those 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 (including stimulating, or suppressing or modifying processes in other body parts)?
Additional forms of 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.
This 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/en/chemoton/the-chemoton-theory
In all these contexts, use of information requires physical mechanisms for capturing, encoding, storing, and manipulating information, which can then be used in performing those functions, e.g. information about how and when to initiate or modify some information-using process.
Below I attempt to provide (in some cases partial) answers to these questions, a task which, of course, requires information processing by me.
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.
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.
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, just as 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 came up
with entirely mistaken theories about what was going on. Correcting those
mistakes required development of new apparatus for thinking about space and
time and our location in space. The human genome proved rich enough to be
capable of producing better theories, but that took quite a long time and
also required production of some entirely new hypothesized features of the
universe.
Reminder
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. 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.
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 the 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.
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.
Uses of information by human-designed machines
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.
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, as happens during insect metamorphosis?
The above facts suggest the following conclusions
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!
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, 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 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!
Of course, not all living organisms have such abilities, e.g. trees and
grasses do not.
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.
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
HUMAN HISTORY SHOWS THAT WHAT SEEMS TO BE OBVIOUSLY TRUE CAN TURN OUT TO BE
SERIOUSLY MISTAKEN
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. 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
https://cogaffarchive.org/misc/s/schrodinger-life.html
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.