Ecology Embodiment – John Siraj-Blatchford

Why development may need repetition, exploration and a world that answers back

By John Siraj-Blatchford

What is play for?

We often answer this question by listing the things children may learn while playing. Play supports language. Play develops social skills. It promotes creativity, problem solving, physical development and, increasingly, self-regulation. Much of this may be true. But lists of outcomes do not really explain play.

They tell us what may happen during play. They do not explain why play should have become such a persistent feature of human development.

Perhaps we have been looking at the question from the wrong end.

A developing organism must proceed into a future it cannot fully predict. The particular obstacles, materials, other organisms and opportunities it will encounter cannot all be known in advance. How does development proceed when the path ahead is not already available as a plan?

To explore that question, I want to begin not with children, but with one of the most influential images in developmental biology.

Waddington’s developmental landscape

C. H. Waddington’s epigenetic landscape remains one of the most influential images of development.

In the familiar picture, a ball rolls down a landscape of branching valleys. As development proceeds, some routes become increasingly canalised and other possibilities become less readily available (Waddington, 1957).

The image was important because it displaced any simple idea that a gene directly determines a final outcome. Development has a history. Genetic and environmental influences affect the route taken, and where development has already gone helps condition where it can go next.

Waddington later used the term chreod for a canalised developmental pathway. He also distinguished homeorhesis from homeostasis. Homeostasis refers to the maintenance or recovery of a relatively stable state. Homeorhesis refers to stability within change: the tendency of a developing system to maintain or regain its trajectory.

These are concepts of organised flow, not of passive movement through a finished landscape.

The surface of Waddington’s familiar landscape should therefore not be treated as an independently existing terrain. Nor should the ball be interpreted too literally. A marble remains a marble whichever valley it enters. An embryo does not. It changes continuously as cells divide, differentiate, move and enter new relations. Its previous development affects what it can subsequently become, which signals it can respond to and what forms of organisation remain possible.

A dynamic rendering of Waddington’s epigenetic landscape. Both the developing form and the landscape change as development proceeds.

Development changes the participant, and the field of possibilities through which further development proceeds...

A path made in the walking

For thinking about learning and cognitive development, a water channel may provide a better image.

Imagine water moving down a hillside. Its earliest passage may be dispersed and irregular. The gradient, vegetation, soil structure, obstructions and saturation of the ground all influence where it flows. But the water also alters the terrain. It erodes some surfaces, deposits material elsewhere and begins to form channels.

Later flows are more likely to enter some of those channels. Repeated passage may deepen them, increasing the probability that subsequent water will take a similar route. Yet the flow may also encounter an obstruction, overflow an existing channel or open another route.

The pathway is neither dictated by the landscape alone nor created by the water alone. It emerges through their continuing relation.

Living development adds another dimension. A stream changes the terrain but remains water. A developing organism is itself transformed through the journey.

An embryo differentiates. A root grows and changes its own position. A neuronal growth cone extends an axon behind it. A child acquires new bodily, social, material and symbolic possibilities.

Cellular exploration within development

The more we learn about developmental plasticity, the less satisfactory it becomes to imagine genes as a blueprint containing a detailed description of the organism to be constructed. Genes are indispensable, but development arises through gene activity in cellular, bodily and environmental contexts. Biological inheritance does not have to specify every particular encounter or route in advance. West-Eberhard (2003, 2005), among others, has argued forcefully against treating organisms as genetically programmed.

At the cellular level, movement does not always begin with a destination being selected and a route then executed.

Andrew and Insall (2007), studying chemotaxis in Dictyostelium (the movement of cells in slime mold), found that in shallow chemical gradients directional movement could arise through biased choices among protrusions. New pseudopods were commonly produced through the splitting of existing ones. The chemical gradient did not have to specify, in advance, the exact point at which the next protrusion should appear. Instead, recurrent protrusive activity generated possibilities, and local conditions biased which possibilities were continued.

A separate imaging study makes this exploratory motion at the cellular surface strikingly visible. Leijnse and colleagues (2022) showed filopodia (the finger-like protrusions of cells) growing, shrinking, twisting, buckling and sweeping through three-dimensional extracellular space.

Filopodia actively explore the space surrounding a cell. They extend, withdraw, rotate and bend rather than simply following a route specified in advance.
Open animation / source

The motion is distinctive…

No complete route is identified and then followed. The movement generates possibilities for encounter. Local conditions will vary. Some movements continue; others do not.

The activity recurs. The encounter changes what the next activity can become..

This does not make genes unimportant. It suggests something more interesting. Biological inheritance may organise the means through which possibilities are generated and responded to without specifying every particular pathway that development will take.

Genes may help construct the dancer and its repertoire. They need not encode every step…

The spiral dance

This developmental pattern becomes dramatically visible in the growth of plant roots.

A root growing through soil encounters an extraordinarily heterogeneous environment. Particles vary in size. Soil is compacted unevenly. Water and nutrients are irregularly distributed. Stones and other obstacles interrupt possible routes.

The root cannot know in advance where an opening will be.

Taylor and colleagues (2021) provide a remarkable visual illustration. Growing rice roots engage in a recurrent helical movement known as circumnutation. In time-lapse footage, the root tip appears to perform a slow spiral dance as it grows.

A growing rice root performs a recurrent spiral movement known as circumnutation. The movement helps the root encounter openings in an unpredictable substrate.
(Taylor et al. 2021, Movie S1).

The wild-type roots show striking helical circumnutation. The hk1 mutants grow much more predominantly downwards.

At first glance, the movement may look inefficient.

Why not simply grow downwards in a straight line?

But that question only makes sense if the destination and the conditions of travel are already known. A straight line is efficient when the route is known. The root’s problem is precisely that it is not.

Taylor and colleagues compared ordinary rice roots with mutant roots in which circumnutation was greatly reduced. The difference mattered when roots encountered obstacles and heterogeneous substrates.

Roots grow through a 1.5 cm gravel layer towards gel below. (Taylor et al., 2021, Movie S10).

In the gravel experiment, 77 per cent of the wild-type roots penetrated into the gel layer below, compared with 48 per cent of the less-circumnutating mutants (Taylor et al., 2021).

The spiral is not wasted movement around the real path.

The spiral movement helps find the path.

Recurrent movement repeatedly brings the growing tip into contact with slightly different conditions. Resistance and possibility are encountered from shifting positions. The root grows through the encounter, and every increment of growth changes the location from which the next movement begins.

The movement repeats but neither the encounter, nor the traveller remains the same..

This suggests a more general developmental principle. Repetition need not be the opposite of progress. What appears repetitive from the perspective of a predetermined destination may be systematic exploration where the destination cannot yet be known.

The dance continues inside us

It would be easy to treat the root as merely a convenient botanical metaphor for human development. But a recognisable organisational principle is also visible within the developing nervous system.

At the growing end of an axon is a highly motile structure known as a growth cone. Developing neurites, tipped by growth cones, encounter guidance cues as neural pathways form. Growth cones extend filopodia that probe, attach, move and withdraw.

Tamada and colleagues (2010) used three-dimensional time-lapse microscopy to document the dynamics of hippocampal growth-cone filopodia. Individual filopodia showed autonomous screw-like rotation. The authors explicitly discuss filopodia as structures that sample the external environment for guidance cues and suggest that rotational movement may increase the volume of extracellular matrix that each filopodium can probe.

Filopodia on a neuronal growth cone rotate and explore the surrounding extracellular space as a developing neurite changes direction. The time-lapse shows a hippocampal neuronal growth cone migrating in three-dimensional collagen gel.
Open animation / source

A plant root and a neuronal growth cone are not biologically identical. The mechanisms differ, and a resemblance in movement does not establish homology.

But the organisational recurrence is difficult to ignore.

Each involves recurrent activity within a structured but incompletely specified field. Each encounter alters the developing system and the position from which further activity proceeds.

The path emerges in the going, while the traveller is transformed in the travelling.

Development has not suddenly become Cartesian because we have entered the nervous system. There is no obvious reason to assume that cognitive development must begin from an entirely different logic.

Watch a child at play

Sand-and-water play typically shows recurrent exploratory engagement. The broad pattern of activity persists, while the affordances and resistances encountered vary with materials, tools, flows and social participation.

Recurrent play is not exact repetition. Each return varies the relation among the child, the materials, the tools and the effects produced.

To an adult expecting development to proceed as a linear curriculum, the activity can appear repetitive. The child is doing the same thing again and again. Surely it is time to move on?

But now think again about the root…

The child carries a wooden block. A bucket. Sand. Water. An object that is too heavy. A container that spills. Something another child believes belongs to them. A large object that will not pass through the available gap. Something that requires another child’s help.

The pattern repeats. Each encounter changes the child, the materials and what becomes possible next.

Recurrent activity provides continuity while materials, forces, spaces, artefacts and other people provide variation. The child repeatedly re-enters a world that answers differently, but never from exactly the same developmental position.

The child does not need to possess, in advance, the concepts that may eventually become available through these encounters. Weight, volume, distance, containment, obstruction, ownership, cooperation and loss are not necessarily the starting instructions for the activity. They become differentiated within participation.

This is why I have come to define play as:

Free participation in a world that answers back.

The word free matters. It does not mean detached from structure, resistance or constraint. Quite the opposite.

Objects fall. Water spills. Structures collapse. Bodies tire. Other children object. Rules emerge.

The world answers back…

What is not fully specified in advance is the particular pathway of engagement. The child remains able to revisit, vary, redirect and combine activity.

Like the spiralling root, the child may appear to take an unnecessarily indirect route only if we assume that someone already knows exactly where development should go.

What if this is what play is for?

I want to suggest a hypothesis.

Play may be an evolutionary answer to the impossibility of prediction.

A developing human cannot be genetically supplied with advance knowledge of every social, material and cultural environment they will inhabit. Evolution could not have specified the smartphone, the supermarket, the traffic light, the written number system, or the rules of cricket.

Nor is it enough simply to say that culture fills in what genes leave blank. The child must participate in cultural environments that are themselves changing, internally differentiated and often unpredictable.

What evolution can conserve are organised means of entering into differentiated environments and finding out what they afford.

From cellular protrusion, to the circumnutating root, to the probing growth cone, biology repeatedly shows us organised activity generating contact with conditions that cannot be fully specified beforehand.

I am not claiming that these are the same mechanisms. I am suggesting that they prepare us to recognise a developmental pattern that is easy to miss when we look at children.

Play is nature’s way of enabling the child to develop in a world that cannot be predicted in advance.

Its recurrent movements may look wasteful from the perspective of a curriculum that already knows its destination. But development has a different problem.

It must find ways forward in a world it cannot completely predict.

NOTE: In the embodied and ecological extension of canalisation that is proposed here, the term refers to the increasing robustness and revisitable availability of a developmental pathway of participation. This is not simply a neural track inside the child. It is a historically formed relation among bodily action, attention, affect, materials, language, other people and institutional arrangements. Neural changes are involved, but they are one material stratum within this wider developmental history.

What, then, is the adult for?

The educational implications of this argument are easily misunderstood.

It is not an argument that adults should stand back and let development take its natural course. Water will make a channel, but not every channel takes it somewhere we would wish it to go.

Imagine instead the possibility of adults and children participating in the co-construction of developmental pathways. The educator cannot prescribe the route in advance, but neither are they absent from the conditions through which a pathway becomes possible.

We can also think of constructing ‘flood-relief’ channels.

When water has repeatedly followed one route, telling it to flow elsewhere achieves very little. The existing channel has become a path of least resistance. Effective intervention changes the conditions of flow. Another route is opened, made accessible and repeatedly available. With sufficient passage, the new channel may itself deepen and become increasingly easy to revisit.

The adult can help make another pathway available.

Consider conflict between young children.

One child wants an object held by another. Grabbing has worked before. Shouting recruits adult attention. Pushing removes an obstacle. These need not be calculated strategies. They are immediately available pathways of activity, strengthened by histories of use and consequence.

An adult may prohibit them:

“Don’t grab. Use your words.”

But instruction alone does not necessarily create a revisitable alternative pathway.

HighScope’s approach to conflict resolution offers a useful example. The adult approaches calmly and stops hurtful actions; acknowledges feelings; gathers information; restates the problem; asks for ideas and supports the children in choosing a solution; and remains available for follow-up support (HighScope, 2018).

The educational significance does not depend on children memorising a six-step verbal routine and executing it independently.

At the point where conflict occurs, the adult repeatedly makes another organisation of participation available.

Feelings can be acknowledged. Different accounts can be heard. The problem can become available for shared attention. Possible actions can be generated. A solution can be tried.

Conflict happens again. But the history from which the next encounter begins is no longer quite the same.

At first the alternative route may require substantial adult participation. It may be shallow and easily abandoned. Yet recurrent participation can make it increasingly revisitable.

The adult, in this sense, helps to cut a flood-relief channel.

This is not canalisation acting as a pedagogical technique. It is pedagogy contributing to the conditions through which an alternative pathway may become selectively stabilised.

It also helps us move beyond a sterile choice between direct instruction and standing back from children’s activity. The educator participates in the developmental landscape. Their words, responses, routines, artefacts and organisation of the environment alter the conditions under which activity proceeds. The child’s response, in turn, alters what the adult can appropriately do next.

Sometimes the educator teaches directly. Sometimes they introduce a material, alter a space, join an activity, bring children into relation, offer language, tell a story or protect the time required for a pathway to be revisited.

The pedagogical question is therefore not simply:

What should I tell the child to do?

Nor is it only:

What is the child interested in doing?

It is also:

What pathways are being made here, and what alternative pathways might my participation help to make available?

That question changes the meaning of repetition. It changes the meaning of provision. And it changes the role of the educator.

Everything to play for

The embryo transforms.

The cell extends.

The root spirals.

The growth cone probes.

The child plays.

And the educator participates.

The biological mechanisms are different. The comparisons should not be mistaken for claims of identity. Yet across these levels we can recognise a recurrent developmental problem.

Where the future pathway cannot be completely known in advance, development requires ways of generating encounters with possibilities.

Differential conditions answer back.

Some pathways become increasingly robust and revisitable.

History changes what can happen next.

Perhaps play has been difficult to explain because we have kept asking which particular outcome it produces.

The better question may be what kind of developmental problem play solves.

A developing child must proceed in a world they cannot completely predict.

They need ways of finding openings.

They need, sometimes, to dance.

And adults need to understand that the most important pathway may not be the one we drew before the child began.

That is why we have everything to play for.

Category: Ecology Embodiment

Everything to Play For