The Natural History of Mattering: III. The Cell That Became a Community

We have moved from an organism that responds to its environment to organisms that become significant to one another.

But there is another possibility.

What if two formerly independent living systems do not merely interact?

What if they become parts of the same organisation?

That is the remarkable story of eukaryotic cells.

The endosymbiotic revolution

Modern eukaryotic cells contain mitochondria, descendants of bacteria that became endosymbiotic partners within an ancestral host cell. The precise identity of the host, the bacterial partner and the sequence of events remain subjects of active research, but the endosymbiotic origin of mitochondria is one of the central and robust features of current accounts of eukaryogenesis.

Plastids, including chloroplasts, have a corresponding origin from cyanobacterial ancestors.

The astonishing thing is not merely that one organism lived inside another.

It is that the relationship became integrated into a new biological organisation.

From partners to components

The ancestral bacterium was once an independently organised organism.

Over evolutionary time, the relationship changed.

Mitochondria retain traces of their bacterial ancestry, including their own genomes, but they have lost many genes and become deeply dependent upon the host cell; most mitochondrial proteins are now encoded by nuclear genes.

The former partner became an organelle.

That is a remarkable transformation in individuation.

The question is no longer simply:

How do two organisms affect one another?

It becomes:

When does one organism become part of another organism's organisation?

The topology changes

Our previous post described relational significance as the point at which another organism becomes consequential to an organism's own organisation.

Endosymbiosis goes further.

The other organism is no longer merely outside.

It becomes part of the system's internal organisation.

The boundary of the larger organism has effectively been redrawn.

What had once been:

organism A ↔ organism B

becomes something more like:

organism A + integrated former organism B → a new organisation

The topology has changed at the level of individuation itself.

What happened to the bacterium's value?

This gives us an intriguing question.

The ancestral bacterium had its own biological value.

It maintained its own organisation.

It responded to its environment.

After integration, the mitochondrion still performs functions that are essential to the larger cell, while its own organisation is deeply constrained by the host.

Its individuality has not simply vanished.

It has been transformed.

The mitochondrion remains a distinct biological lineage and compartment, but it no longer lives as the autonomous organism it once was.

So what happens when one value-organised system becomes a component of another?

Perhaps the answer is:

its value becomes nested within a larger organisation of value.

Nested value

This is a different phenomenon from social coordination.

Two bacteria can signal to one another while remaining independent organisms.

A mitochondrion and its host are different.

Their relationship has become constitutive of the larger organism.

The host's organisation depends upon the mitochondrion.

The mitochondrion's organisation depends upon the host.

The relation has become structural interdependence.

Neither can simply be understood in isolation.

A new individual emerges

This is why the origin of the eukaryotic cell is so important for our project.

The eukaryotic cell was not simply a larger bacterium.

It represented a new level of organisation assembled through an evolutionary merger involving previously distinct lineages. Current research describes eukaryogenesis as a major transition in biological complexity, while emphasising that the precise sequence remains unresolved.

A new individual emerged from a history of interaction between individuals.

That complicates any simple distinction between:

individual

and:

collective.

Sometimes a collective becomes an individual.

Integration rather than aggregation

The distinction is crucial.

A colony of bacteria can contain many organisms.

A eukaryotic cell contains many internal processes and descendants of once-independent organisms.

But the latter is not merely an aggregation.

Its components are integrated into a common organisation.

Their reproduction, metabolism and regulation become increasingly coordinated through the larger system. The evolutionary transition involved extensive gene transfer from the endosymbiont to the host nucleus and increasing host control over the former symbiont.

The result is something new:

organised unity without complete homogeneity.

Individuation is therefore not simple separation

We often imagine an individual as something bounded against everything else.

Endosymbiosis suggests a different picture.

An individual can be constituted through incorporated difference.

The eukaryotic cell became what it is partly by taking another lineage into itself.

Its individuality is therefore relational in a surprisingly literal sense.

This may eventually prove important when we return to multicellular organisms.

From interaction to incorporation

We can now extend our emerging sequence:

biological value

↓

relational significance

↓

signalling and coordination

↓

integration

↓

nested organisation

The important point is that integration is not simply "more cooperation".

It is a transformation in the level at which organisation is individuated.

The host changes too

The transformation was not one-sided.

The host cell had to change as well.

Housing and controlling a formerly independent symbiont created new evolutionary pressures and new forms of cellular organisation. Current research continues to debate exactly how those changes unfolded, but there is broad agreement that mitochondrial acquisition was central to the emergence of the complex eukaryotic cell.

The symbiont changed the host.

The host changed the symbiont.

The resulting system was different from either.

That is perhaps the deepest lesson of endosymbiosis:

a relationship can transform both participants by creating a new level of organisation.

A new kind of mattering

We should still avoid calling this social mattering.

The relationship is not social in the sense we are developing.

But it gives us another form of relational significance.

The former symbiont is consequential to the host.

The host is consequential to the symbiont.

Their continued organisation becomes intertwined.

This is relational significance becoming constitutive of individuation.

That is a major step beyond signalling.

And then there were more

The same broad principle appears again in plastids.

A cyanobacterial lineage became incorporated into eukaryotic cells, eventually producing chloroplasts and related plastids. These organelles too retain bacterial ancestry while functioning as deeply integrated components of their host cells.

Life therefore repeatedly found a way to turn relationship into organisation.

A former partner becomes a component.

A component becomes indispensable.

A new individual emerges.

The next problem

We have now encountered something more radical than organisms influencing one another.

We have seen organisms becoming parts of other organisms.

That leaves us with a question that will recur throughout this series:

When does a collection of living systems become a new individual, and what happens to the value of the components when it does?

The next transition will take us in another direction.

Instead of one organism incorporating another, we will look at living systems that remain distinct yet produce remarkably organised collective behaviour.

The Collective Without a Centre

The Natural History of Mattering: II. When Organisms Become Significant to One Another

We began with a bacterium whose environment can matter to it without any social relationship.

Now we can introduce another organism.

This changes the problem.

A second organism can alter the conditions under which the first lives.

It can compete.

Cooperate.

Provide resources.

Consume them.

Produce chemicals.

Alter the environment.

And the first organism can respond.

The question is:

When does another organism become significant to an organism rather than merely part of its environment?

From environment to relation

Suppose bacterium A produces a chemical that changes the behaviour of bacterium B.

If B responds in a way that alters conditions for A, a feedback loop begins:

A → B → A

The organisms have become consequential to one another.

That does not yet make them a society.

But something has changed.

We have moved from organism-and-environment to organism-and-organism coupling.

This is the beginning of what we have called relational significance.

The signal

This is where our distinction between signal and sign becomes useful.

A bacterium can release a molecule that another bacterium detects.

The receiving cell's regulatory machinery responds.

No symbolic interpretation is required.

The molecule is a signal because it engages another organism's organisation.

It is not a sign in the semiotic sense.

The significance remains biological.

Quorum sensing

Bacterial quorum sensing gives us a particularly revealing example.

Bacteria can produce and detect extracellular signalling molecules called autoinducers. As these molecules accumulate, their concentration can provide information about population density and, in some systems, community composition. Detection can trigger coordinated changes in gene expression across a population.

The consequences can be substantial.

Bacteria can coordinate activities such as bioluminescence, biofilm formation and production of other compounds, behaviours that can be far more effective when performed collectively.

The important point for us is not that bacteria have invented a primitive language.

They have not.

It is that the activities of individual value-organised cells have become coupled through signals produced and detected by other cells.

Another organism becomes consequential

The signal therefore creates a new kind of relation.

A bacterium's behaviour can alter the chemical environment of its neighbours.

Those neighbours respond.

Their responses alter the conditions again.

The individual organism remains value-organised.

But its possibilities are now partly shaped by the activities of others.

We can express the transition as:

individual value → signal → response → altered conditions → further response

Relational significance has appeared.

But is this social?

Not yet, at least not necessarily.

Quorum sensing is sometimes described as bacterial communication and collective behaviour, and it can produce population-wide coordination.

But we should resist simply declaring that every bacterial signalling system is a social system.

Our distinction is more cautious.

Collective coordination can arise from coupled value-sensitive responses.

Social mattering is a stronger claim: recurrent relations have become organised in ways that constitute a social structure.

The distinction gives us somewhere to go.

The collective appears before the social

This is an important point.

A group can behave collectively without possessing anything like a society in the richer sense.

The members do not need a shared representation of the whole.

They need only respond to conditions produced partly by one another.

The result can be an organised collective pattern.

This is the same principle we later encounter in much larger systems.

Collective form can emerge without a central controller.

Signals can connect many individuals

Quorum sensing makes the transition especially clear because the same signalling system can affect many bacteria.

An individual cell contributes to the concentration of a signal.

Other cells detect that changing concentration.

Once a threshold is reached, many cells can alter their behaviour together.

The consequence is no longer adequately described by looking at one cell in isolation.

The population has acquired a new level of organisation.

And yet the individuals remain value-organised

We should not lose sight of the foundation.

The bacteria have not stopped being individual living systems.

Each cell still maintains itself.

Each has its own metabolism and regulatory organisation.

The collective pattern emerges because those individual systems are coupled.

This is crucial to our project.

We are not replacing biological value with social value.

We are asking how biological value can become organised relationally.

Relational significance is our bridge

We can now see why the intermediate concept is useful.

At the beginning:

biological value — conditions matter to the organism itself.

Now:

relational significance — another organism's activity becomes consequential to the organism's own organisation.

Later:

social mattering — those relations become sufficiently recurrent and organised to constitute a social system.

This gives us a conceptual bridge from the cell to the social world.

The next complication

There is, however, a much more radical way for relationships among living systems to develop.

Instead of remaining separate organisms that signal to one another, previously independent organisms can become integrated into a larger organismic system.

Then the question changes.

What happens to the value of an organism when it becomes part of another organism?

And what happens to the identity of the larger system when it incorporates another living system?

That takes us to one of the strangest transitions in the history of life:

the incorporation of one cell into another.

The Natural History of Mattering: I. Before Society: What Can Matter Without Relationship?

We have spent a long time asking how biological value can become social mattering and, eventually, meaning.

But perhaps we have been starting too far up the ladder.

Before there is society, there are organisms.

Before there are relationships, there are living systems whose own organisation makes some differences consequential and others not.

So let us begin again.

What can matter without relationship?

The single cell is enough

A bacterium has no society to belong to.

No language.

No nervous system.

No social identity.

Yet it is not indifferent to its environment.

It must maintain its organisation in changing conditions.

Nutrients become available or scarce.

Temperature and pH change.

Toxic substances appear.

Oxygen may become more or less available.

Bacteria possess regulatory systems that alter metabolism, growth and other cellular processes in response to such changes.

Nothing about this requires us to imagine a bacterium "knowing" what is happening.

The point is simpler.

Its organisation makes some differences consequential to it.

Chemotaxis gives us a particularly clear case

Consider chemotaxis.

Bacteria can detect changes in concentrations of chemical substances and bias their movement towards conditions containing beneficial compounds or away from harmful ones.

The bacterium does not need a representation of food as an object.

A chemical difference is detected.

A signalling pathway changes.

The flagellar motor changes its behaviour.

The bacterium's movement changes accordingly.

We should resist the temptation to call the chemical a sign.

It is more primitive than that.

There is no need for symbolic construal.

There is simply a difference that makes a difference to an organised living system.

Value before meaning

This is why Edelman's notion of biological value remains such a useful starting point.

Value need not be conscious preference.

It need not be represented.

It need not be named.

It is enough that the organisation of the organism differentiates between conditions according to their consequences for its continued activity.

In that sense:

value precedes meaning.

And perhaps, more fundamentally:

mattering precedes meaning — but not yet social mattering.

This last qualification is important.

We have been using mattering specifically for the social organisation of biological value.

So we need another term here.

Relational significance has not yet appeared

A bacterium can be value-sensitive without another organism becoming significant to it.

Its environment can affect it.

But that is not yet a relationship between participants.

The distinction we proposed before beginning this series therefore becomes useful:

biological value concerns what is differentially consequential for an organism's own organisation;

relational significance concerns the way another organised system becomes consequential to it;

social mattering begins when such relations become recurrently organised into something recognisably social.

At the bacterial starting point, we have the first of these.

We need not yet posit the other two.

The organism does not need a world of symbols

This also helps separate our project from the problem of meaning.

A bacterium can navigate chemical gradients without possessing a symbolic representation of its surroundings.

Indeed, chemotaxis is often described as navigation towards more favourable chemical conditions, and it can involve remarkably sensitive detection of changes against widely varying background concentrations.

The system is therefore capable of value-sensitive regulation without semiosis.

That is exactly what we want at the beginning of the series.

The boundary of the self matters

There is another important feature here.

For the moment, the value system and the organism coincide reasonably neatly.

The bacterium maintains its membrane, metabolism, internal chemistry and genetic machinery.

Conditions that support these processes support the organism's continuing organisation.

Conditions that disrupt them threaten it.

The boundary between:

the organism

and:

what matters to the organism

is therefore already enough to give us a primitive value landscape.

But it remains an individual landscape.

There is no social topology yet.

Even stress is still individual

Bacteria also possess sophisticated stress responses.

Nutrient limitation, oxidative stress, osmotic changes, temperature shifts and other challenges can trigger coordinated changes in cellular activity.

Again, we should not anthropomorphise this.

The point is not that a bacterium feels stressed.

It is that its organisation responds differently to conditions that threaten its functioning.

The distinction is crucial:

physiological significance is not psychological experience.

We can study value-sensitive organisation without deciding anything about consciousness.

What happens when another organism enters the picture?

Now the interesting problem begins.

A bacterium does not live in an empty world.

Other organisms are already there.

They may alter chemical conditions.

Consume resources.

Produce metabolites.

Create toxins.

Provide nutrients.

Form associations.

The environment is therefore already becoming relational.

But we should not call every ecological interaction social.

An organism can be profoundly affected by another organism without that other organism becoming a social participant.

The distinction matters.

From environment to relation

Suppose organism A alters a condition encountered by organism B.

If B responds because that condition affects its own value-sensitive organisation, we have a coupling.

If B's response then alters A's condition, a feedback loop appears.

Now:

A affects B → B affects A.

This is more than an organism and an inert environment.

It is the beginning of relational significance.

But even here, we should not rush to "social".

A recurrent interaction has to become organised in particular ways before that word earns its place.

The next step is signalling

This is where our earlier signal/sign distinction will become useful.

A difference generated by one organism can engage the value system of another.

At this stage, the signal is not yet a sign.

It does not need symbolic meaning.

It simply carries a consequence through the interaction.

Bacterial chemotaxis gives us the individual side of this story.

The next question is what happens when bacteria themselves begin producing signals that alter one another's organisation.

Then the mattering landscape will no longer belong entirely to isolated organisms.

It will begin to have a relational shape.

What we have established

We have deliberately started below society.

A bacterium can:

maintain its organisation;

distinguish among environmental conditions;

alter its activity in response;

move towards favourable conditions;

respond to conditions that threaten its functioning.

None of this requires:

language;

symbolic meaning;

social identity;

or even another organism.

This gives us our baseline:

biological value can exist without relationship.

And that gives us the question we need next.

What happens when another value-organised organism becomes part of the system?

When Organisms Become Significant to One Another