The Drawing that Ate Architecture

Some time in 1969, the 30-year-old critic and historian Charles Jencks made a blobby diagram that would become as iconic as any drawing of a building or city by an architect. It was labelled ‘The Evolutionary Tree’, yet is really a kind of landscape image. Thick curving felt-pen lines drawn by hand portray six lightly shaded pulsating chronological strands of architectural activity moving from left to right across the page. They sometimes widen to merge with adjacent strands, or become as thin as a single line, but finally end up more or less the same width as they started. The lower strand pulsates the least and sits flat on the bottom. It is a kind of stable ground or coastline away from which the others float, moored only by two narrow umbilical cords. The liberated yet interlinked blobs freely fluctuate in an unending dance – expanding and contracting, merging and diverging. Their restless fluidity is magnified by the unwavering beat of thin vertical lines that mark the passage of eight decades. Architecture constantly throbs – apparently.

From a distance this idiosyncratic portrait of the twentieth century appears to be a single continuous densely populated landscape perforated by serpentine lakes of inactivity. Closer up it is a series of idiosyncratic spaces, a flowing interior environment filled with the names of architects clustered around the labels of the most significant architectural tendencies. The image conveys the sense that there is a dense biodiversity of experiments at any one historical moment as architects test different possibilities within semi-autonomous streams of interrelated work. Labels get larger and bolder as the clusters aggregate. The biggest – such as UTOPIAN, HEROIC, FASCIST, BUREAUCRATIC, and POP – name whole blobs as territories of investigation that have clearly defined borders and yet are linked to adjacent territories by two or more thin isthmuses.

The least undulating unperforated stream at the bottom of the drawing is symptomatically the one least influenced by architects. Only designers like Buckminster Fuller and the Eames, who challenged the conventional figure of the architect, enter this UNSELF-CONSCIOUS zone of activity that is driven by technologies, regulations, infrastructure, services, chemicals, drugs, electronics, vernaculars, popular taste, consumer culture, eclecticismsand improvisations. The drawing even suggests that this steadily evolving yet seemingly solid ground oblivious to the polemics of architects might be eighty per cent of the built environment. Architecture is implicitly understood to be a form of agitation detached from the everyday landscape with only an indirect or occasional engagement with normative lived space. Architectural discourse is literally portrayed as a disconnection from the very world it claims to address – floating away and interacting with itself under very little external constraint. To read the drawing even more literally, architects don’t live in the world. They inhabit parallel worlds of their own making. To visualise this sustained detachment is not to criticise the architectural animal. On the contrary, the drawing seems to marvel at the idiosyncratic behaviour of these free-floating yet highly competitive creatures.

Architectural discourse appears to have an ever-changing shape but a constant self-sustaining ecology. It is a kind of organic system, a quivering swarm of interacting questions, concepts and personalities in which everything affects and is affected by what is around it. The distinct dynamic form of the field is produced by the movements of those who inhabit it. Architects unwittingly shape their own pulsating creative environment and this space might be more radical than any of their projects. They are like a flock of birds that endlessly generates a fluid shape in the sky, or a school of fish making forms in the water, but is not able to see this collaborative architectural effect from the inside – until a historian draws it for them as a kind of mirror, as if saying ‘Look at what you have made together’ or ‘Look at your own organism,’ which are the same thing.

Yet this is not simply history, or a simple history. The polemical ecological drawing reaches back to 1920 but also forward to 2000, mapping activity that hasn’t happened yet. Jencks designs a future for the field, with the predicted mega-clusters of BIOMORPHIC and SEMIOLOGICAL emerging at the end of the twentieth century that seem to be inspired by the biomorphic form of the diagram itself and its attempt to represent the pluralism of signs that semiology analyses. It is as if the drawing itself embodies the future. In the late 1960s, when so many experimental architects were producing pulsating inflatable biologically inspired architectural projects in the name of new technologies and life forms, Jencks visualised the history and future of the field in the same terms. History itself had become an architectural design in its own right, a living biotechnical organism that houses or digests architects.

Jencks was finishing his PhD at University College London under the supervision of the writer and critic Reyner Banham at the time, and likewise aimed at a paradoxical ‘history of the immediate future’, as Banham first put it in 1961 – charging historians with the responsibility to ‘extrapolate’ from the past through the present into the likely future.1 In fact, only the historical left side of the diagram going back to 1970 was included in the final thesis submitted in January of that year, as if the futuristic right section would not be an acceptable form of scholarship, even to Banham.2 The full drawing was first published that October in Architectural Design – the magazine that quickly became Jencks’ platform for a continuous stream of articles and books in endless revised editions and translations that had by far the largest global readership of any critic or historian for decades.3 This huge audience across borders, languages, and time was somehow tied to the blobby diagram. Jencks didn’t just make the drawing. It made him.

The image kept reappearing for almost half a century in seemingly endless variations, as if it were an animation – a living drawing whose whole point was to treat architecture as a kind of life form. This pulsating image of pulsating architecture had an ability to absorb, represent, defend and promote diversity. It was never simply an image of existing architectural culture. It was a manifesto for non-hierarchical multiplicity. The exact information in the image was less important than its form. Jencks tried to give it a scientific aura by arguing that it was developed from structuralist analytical techniques, claiming to have begun it by systematically positioning architectural activity in a three-dimensional space defined by three sets of binary oppositions. But what this looked like and how it was turned into a two-dimensional diagram is unclear, other than the fact that each opposing term of the binaries became a horizontal stream.

The labels of the streams were anyway so polemically vague that they could probably be changed or switched without anyone noticing. SELF-CONSCIOUS versus UNSELF-CONSCIOUS is a clear binary but LOGICAL versus IDEALIST and INTUITIVE versus ACTIVIST are far from obvious. It is anyway unlikely that any reader ever studied, believed, or even cared about the particular designated position of the hundreds of architects, buildings and movements within each version of the drawing. Architects placed within the drawing often complained to Jencks about where they were positioned – as if an architect could ever be happy with any assigned location in a non-hierarchical landscape.4 The only real reason to complain is for not having been placed anywhere. Some historians likewise grumbled about the continuation of the evolutionary paradigm of art history that is at least as old as Giorgio Vasari’s narratives of the mid-sixteenth century, the construction of such a singular image, the simplifications of the labels, and even the very idea of labelling – all the while trying not to seem overly invested, as if Jencks were not a worthy adversary, or too slippery, or too good at his own game.

But the drawing was never made for rival historians and critics, or for the architects it named, and was precisely not about their self-image. It is more about the cumulative unconscious effects of conscious self-images. None of the many reviewers felt the need to dispute any specific positioning or repositioning as entries shifted location or occupied multiple locations and there were no complaints about the conspicuous absences. It was understood that anything and everything could ultimately be added, moved or erased only to later reappear. The constant form of the diagram was a kind of framework on which the idea of patterns of relative independence and interdependency within architectural discourse could be portrayed. The only thing emphatically rejected was the idea of any singular dominant line or implication of progress.

The drawing visualises an evolving ecology as the real site in which architecture is produced. Its viewers don’t need to care about all the particular positions within it but are somehow reassured by the sense that they too are inhabiting a singular environment that could be surveilled. It is an image of community, of sharing an interior space with immediate and distant neighbours, with those named and those not, with those that have gone and those yet to arrive. The details and even the overall shapes don’t matter in the end. What matters is that at every moment there is a diversity of equally important things going on with a tendency to form clusters that ‘wax and wane’. Almost all the different versions of the diagram default to the seemingly arbitrary number of six streams as if it were a kind of ecological principle that sustains the right degree of diversity, autonomy, interactivity, and interdependency.

Jencks anyway always explained the limitations of the diagram (two-dimensional, schematic, incomplete, personal bias, Western bias, the labels of the streams actually not important, the binaries not really opposites, simplifications to tell a story, the inadequacy of the biological analogy, etc.) as if to insulate it from criticism. But few wanted to criticise. Successive generations of viewers are captivated by the evolving diagram of architectural evolution and even dependent on its image of a total landscape in the way they were once dependent on the ostensible completeness of classical treatises or encyclopedic histories of modern architecture like the monumental one of Sigfried Giedion – which were likewise not so much read as pinned to the wall as a flattering mirror to the field. Ultimately, readers are hooked by the diagram and swallowed by it in imagining that they are located somewhere within it. Yet they cannot appear to take it or Jencks seriously. It is as if there were something illicit about this kind of all-inclusive yet unstable map-making, accentuated by the fact that Jencks refused to seem anxious about it, or about anything. On the contrary, he was a professional enthusiast, exuding palpable pleasure in the endless positionings and repositionings. But this pleasure was an all too serious ethic, implicit in the diagram itself. After all, it was one of the first attempts to acknowledge the huge impact that fascism had on twentieth-century architecture through the 1930s and 1940s – thinning the rest of architectural discourse down to minimal strands.5 The diagram is actually an anti-eugenic manifesto.6

When first introducing the evolutionary tree, Jencks’ PhD thesis said that it showed the constant plurality and semi-autonomous status of architectural movements. Whatever architecture is, it is not one thing, and should never be. The diagram appeared alongside a discussion of the crisis of modern architecture produced by the fact that it was not consistently ‘multivalent’ – repressing both the multiplicity of different kinds of building that were ‘modern’ and the multiplicity of different readings that those buildings fostered. In other words, the pulsating blobs monitor the fate of canonic Modern Architecture since the 1920s but also represent the multivalence within and between works that Jencks would eventually identify as an essential contribution of what he will label as Post-Modern Architecture in the mid-1970s.7 Or, to put it another way, the diagram was already a polemical manifesto for the Post-Modern years before Jencks would invoke that term. In fact, he was calling for multivalence in his first articles when editing Connection, the little magazine he co-founded as a student at Harvard in the early 1960s to condemn specialisation and promote pluralism and hybridity.8 A chapter of the PhD discussing multivalence was already published in November 1967 by the Architectural Association’s journal Arena, which introduced him as ‘an American post-graduate student working in London on a thesis.’9 The PhD was reading modern architecture through what would later be understood to be a Post-Modern lens.

The central hypothesis when the full diagram was published for the first time in the October 1970 issue of Architectural Design was that architects working on related questions constitute ‘species’ that evolve in parallel through interaction and self-mutation. They group in ‘traditions’ that are part of a wider shared genetic terrain. Indeed, an architect might be a ‘moving gene pool’ rather than a species. The real species are the evolving streams of shared experimentation. The name of a single designer can appear in multiple disconnected streams. It is as if Jencks is suggesting that the real architect is the stream, the environment formed by the accumulated activity of kindred individuals – or some kind of fusion of organism and environment. He reports that the evolutionary diagram was developed for his forthcoming Architecture 2000 book, even if the version in the book would be completely redone without the hand-drawn lines or imperfectly pasted words and the streams now rendered in solid black to produce the iconic effect of the image – with some significant adjustments to the weighting of the labels like upgrading FUNCTIONALISM, PARAMETRIC, and SPACE-COLONIAL to the status of full blobs.10 The one pink page of Architectural Design flaunting the original diagram was basically an advertisement for the book, or the book in miniature. Even the new version of the diagram was first published in early 1971 as another teaser just before the book came out. It straddled two-page spreads on both sides of the Atlantic in Architectural Association Quarterly and Landscape Architecture Magazine, accompanied by condensed sets of excerpts.11

In fact, the publisher made a poster of the finished diagram before the book came out, ‘printed by Studio Vista on behalf of the AA’ and available for purchase by mail order from the school bookshop. The 24- by 16-inch poster conveyed the independent life of the image as something that could be pinned to anyone’s wall as simultaneously map and mandala. The green blobs filled with swarms of white labels floating against a yellow background reinforced both its environmental attitude and Pop sensibility.

It was no coincidence that the blob at the very centre, charting the moment in which the diagram itself was drawn, is labelled POP over the name ARCHIGRAM. Jencks was teaching alongside all the members of that experimental group at the Architectural Association, where he had been a tutor since 1967, and writing about them in his thesis in a chapter on the binary ‘Pop-Non Pop’ that had already been published in the school journal in 1968.12 The vibrantly coloured poster conveys their inflatable, floating, playful, childlike, non-judgemental, nomadic and pluralist spirit. When seen as a section rather than a plan, the Evolutionary Tree drawing even echoes some of the renderings of Archigram’s Instant City project from the same year, or is echoed by them. The floating bubbles that are only lightly moored to the more stable lower strand of UNSELF-CONSCIOUS work are like the thinly moored balloons holding up the suspended landscape of rippling canopies that temporary define the never-still space of Instant City in a countryside field. The drawing of Jencks suggests that architectural discourse is likewise a kind of itinerant fluctuating space that experiments with ever-changing combinations of new kinds of action and thought to animate an otherwise normative ground. It is not boring. On the contrary, it is some kind of continuous happening, a series of simultaneous, intense, energetic, interconnected, collaborative, social interactions. The drawing also conveys the sense of a signed artwork, the historian as a maker of images, a polemical experimental designer rather than a detached analyst, map-maker, or collector.

The blobby diagram was Jencks’ hook from the beginning and appeared again when his doctoral thesis was belatedly published as Modern Movements in Architecture in 1973.13 Both books – one looking back and the other forward – were largely written in 1969 and linked to each other by the shared diagram that interconnected past and future. Jencks usually positioned himself between the two as a rapid responder to the present, always trying to be the first to label things. The ideology of the diagram meant he had to be non-judgementally interested in everything and exclude nothing. The ravenous diagram took Jencks across the field, across the planet, and across time. He was continually feeding it with the names of architects, buildings, technologies, and concepts – reworking the shapes to fit and monitoring in real time what he started to call the inevitable transition of ‘isms into wasms’.

The sketches of evolutionary trees accompanying the manuscripts in the Jencks archive show chronological clusters of names of architects, works and concepts being formed in successive drafts. Each cluster is gathered under the label of a shared idea before being fully organised into streams capable of absorbing all the architectural activity in an overall category. More precisely, a few possible streams are identified at the beginning but await relabelling, merging, and additional streams as the clusters are refined. Jencks worked in pencil or different coloured pens with a personal system for highlighting the names of any ‘recognised important leader’ in boxes or ‘unifying idea’ in fluffy clouds. Arrows snake between clusters to show connections. Entries are rarely crossed out or dramatically relocated. It is more about adding examples and seeing which shapes might sustain the new interdependencies. Kinship patterns within and between the emergent streams are steadily revealed through a continuous feedback loop between streams and clusters.

At a certain point, the name and number of streams is fixed, and it is only the clusters that move as the drawing is further refined, updated or extended. The outline of evolutionary shapes is not drawn while the positions are repeatedly adjusted and new architects—works—concepts are added, as if the shapes were finally drawn by the kinship relations themselves rather than the historian. But shaping is already happening from the beginning in the positioning and repositioning of each entry. In this sense Jencks constructs schools of thought-experiment rather than simply mapping them. The possibility of making other equally revealing maps, and for all such diagrams of history to change and be interpreted in multiple ways, is the same as the possibility and desirability for multiple equally valuable evolving multivalent architectural experiments at any historical moment. After all, the philosophy of pluralism and multivalence has to be applied to the very diagrams that both record and project it.

Given this visualisation of the history and future of architecture as a Post-Modern landscape, it is surprising that the first edition of Jencks’ most popular and most repeatedly revised book, The Language of Post-Modern Architecture, of 1977 did not include an evolutionary tree. But the first experiment with a visual genealogy of seven strands using images from the book was published the same year in Architectural Design – with Jencks insisting on the diversity of ‘species’ that ‘shelter’ under the defining ‘inclusiveness’ of the Post-Modern label.14

The second edition of 1978 featured a crisp evolutionary tree from 1955 to 1980 that was no longer blobby but restored the pattern of six strands by merging two of them (ADHOCHIST and URBANIST-ACTIVIST). They get ever wider to mark the rapid rise of the Post-Modern without a projection of what might happen next.15 The fourth edition of 1984 preserved the timeframe but greatly increased the number of entries and labels, and the visual sense of continuous expansion, reinforcing the sense of Post-Modern Architecture being all about inclusive multivalence.

Yet Jencks was already talking in 1978 about an equally important parallel set of streams of so-called Late-Modern architecture that called for its own diagram, and started to sketch a pencil version of it at the end of 1979 that mapped the decade of the 1970s in seven streams.16 A year later, it was stretched back to the 1960s and reworked with much more detail into six streams by merging two of them (SHED/ISOTROPIC SPACE and GRIDISM into LATE MODERN SPACE) for Current Architecture, a coffee table book that came out in 1982. Its introduction on ‘The Evolution and Mutation of Modern Architecture’ into Late-Modern and Post-Modern tendencies ends by saying that evolutionary trees help readers ‘thread’ their way through the ‘labyrinth’ of diverse contemporary practices.17 The lengthy surveys of both tendencies begin with full-page versions of their respective trees, the new one of the Late-Modern and a matching revised version of the Post-Modern from 1960 to 1980.18 Yet there is no reference to the trees in the text that follows them, or even to the idea of evolution – as if it were understood to be self-obvious.

In fact, following Jencks’ usual strategy, the pair of trees had first been released as a kind of showy advertisement for the new book on two large-format facing pages of the July 1981 issue of the A.D. News supplement.19 A matching essay talked about the general usefulness of the analogy of biological evolution despite the differences with architectural transformations, the specific advantages of such genealogical trees for both historians and their readers, and the relationships between adjacent streams in the two sets of six ‘architectural species’ being mapped. The main point, as Jencks had always argued, was that the tree drawing ‘keeps one from the provinciality of current debate which sees one of two sects as completely dominant, and, it allows one to understand design trends as internally unfolding entities, as well as ideological schools’.20 The drawing supposedly allows both its maker and viewers to avoid being confined to a single position – and all its associated blind-spots.

Yet the drawing of multiple positions as a celebration of multiplicity is itself a singular position of course. In a polemical gesture revealing Jencks’ own preference-prediction, the Post-Modern streams were placed on the right side of the spread and shown to be still expanding while the Late-Modern ones were contracting – as if declaring a kind of biological victory of the Post-Modern – with the section on Post-Modern architecture in the book symptomatically being a third longer.21 Even so the 1988 edition of Current Architecture testified to the persistence and diversity of the Late-Modern when it updated both trees with new diagrams covering just the 1980s.22

In both supplementary trees, the six streams within both drawings have increasingly merged, but especially with the Post-Modern, as if the ultimate symptom of the Post-Modern would be a single wide richly biodiverse stream. In 1987, Jencks reinforced his personal preference even more by producing a whole new tree of the POST-MODERN CLASSICAL, just one of the labels at the overlap between two expanding streams within the Post-Modern tree – tracing its evolution in four exponentially expanding and ultimately merging traditions from 1960 to 1985.23 The implication was that any part of any tree, but especially of the Post-Modern tree, was itself made of even more detailed trees in a vertiginous intensification of diversity that culminates in a kind of Post-Modern ecstasy of hyper-pluralism.

This ecstasy was first and foremost that of Jencks himself – the ever-expanding delirium of labels, evolutionary trees, and texts in endless mutations and editions, always delivered with the tone and look on the face of delight bordering on illicit pleasure. The description of the Post-Modern is finally a description of Jencks himself. The Post-Modern species he exemplifies thrives on the very idea of the endless mutually self-productive dance between species. In the words of the preface to his Post-Modern Reader of 1992:

Unlikely as it might seem from its name, post-modernism is here to stay. In spite of recently being declared dead… the post-modern paradigm highlights time and evolution… The post-modern movement will be here as long as the forces to which it responds also continue: modernity and the other modernisms, and pre-modern or traditional culture. These very general epistemes have a structural relationship to each other, they bring each other into being and oscillate in fortune like competing species. … Post-modernists look to the past and future equally and position themselves in the present, seeing time as a broken continuum in need of acknowledgement.24

The original evolutionary tree drawing, self-consciously poised between past and future in 1969, was a self-portrait, a portrait of the Post-Modern six years before Jencks could start using the word. This image of an ecology of competing yet interdependent movements would use Jencks to launch its own movement that obsessively called for endless ever more expansive maps of its own expansiveness.

1996 saw a new chart of the still-expanding territory of Post-Modern activity in which the sense of separate streams has almost been completely dissolved by the sheer density and variety of parallel activity.25 All the pulsations and blobbiness have been squeezed out. The space between the six streams is thinned down to dotted lines that start disappearing in the 1970s. The Post-Modern had already become a single flat liquid genetic landscape around sixty names wide. Jencks started to argue that Post- Modern theory was nothing more than a conscious embrace of evolutionary biodiversity and that it even paralleled a certain evolution in the theory of evolution that non-coincidentally started in 1960s when he began to make his own evolutionary drawings: ‘From a theoretical position, post-modernists accept the evolutionary paradigm; that is, they conceive everything as radically historical, with the time and cultural dimension clearly featured. The big bang theory of the universe, with its attendant evolutionary metaphysics, was formulated in the 1960s, in the first period of post-modernism, and recently a self-styled “post-Darwinism” has started to dominate discussion.’26 This was not a radical evolutionary or cosmological turn. In fact, Jencks had engaged extensively with a series of such new and often controversial theories of evolution from his first writings to the last, reframing his work in ever wider and always cosmological terms.27 In the mid-1990s, this became a discussion of ‘cosmic evolution’ as a relentless drive from simplicity to complexity via smooth mutational transitions but also through abrupt extinctions and sudden unpredictable jumps. One of Jencks’ eight new ‘criteria for architecture’ was to embrace the ‘cosmogenic truth’ that ‘there is a basic direction of evolution towards increasing complexity, but it is attained through an oppositional process of gradual improvement and catastrophic change, continuity and jumps, smooth transitions and the Butterfly Effect.’28

Yet symptomatically the structure of Jencks’ smoothly branching then remerging non-jumpy evolutionary tree drawings – in which nothing ever suddenly appears out of the blue or becomes completely extinct – remained remarkably constant. It is as if all possible change, including change in theories of change, were already figured in it. Not by chance did Jencks start making a literal garden landscape in Scotland that represented cosmic time in pulsating waves that were not so different from those of the original drawing. After all, the drawing had never shown evolution as such, but tried to domesticate the idea of evolution by visualising biodiversity as a kind of landscape garden in which species appear in all their interrelationships with friendly labels attached to every plant and every bed of plants. It was always an aspiration rather than a documentation, an aesthetic image balancing continuity and change, disconnection and connection, stasis and mobility. It is no surprise that at a certain point, the moment of the new garden precisely, Jencks paradoxically wanted to equally smoothly account for unpredictable jumpiness – devoting a new series of books to the theme. He even drew an ‘evolutionary chart’ of the multiple theories of change since the nineteenth century. The latest parallel theories that explain sudden jumps as a crucial principle in mathematics, biology, ecology, psychology, and physics are themselves the genetic product of 150 years of continuous genealogical strands.29 In reverse, a single architect, such as Frank Gehry, could be seen to exhibit the whole phenomenon of ‘evolution in action’ understood as the cosmic principle of generating complexity.30

The long-imagined year 2000 finally arrived and Jencks returned to his original blobby drawing, somewhat too favourably comparing its predictions with what actually happened in a new edition of the Architecture 2000 book that offered a corrected diagram of the whole twentieth-century.31 In fact, the new version had been developed for another just-published book to demonstrate that Le Corbusier’s periodic self-reinventions exemplified the survival of architecture itself through ‘continual revolution’.32 Around sixty movements now pulsate the six biomorphic strands. POST-MODERN is the biggest blob since the original book was written but is already dramatically waning under the rising threat of the flanking blobs of NEW MODERNISM and DECONSTRUCTION. Yet BIOMORPHIC has taken over as the biggest and still-expanding growth at the end – as if the diagram were declaring its own victory.

Jencks once again pre-released the drawing in a magazine article. As always, the idea was to promote the forthcoming books, yet it also reinforced the independent life of the ever-evolving drawing, the sense that it organised the books it appeared in, even the sense that it wrote the books – scripting all the narratives and the overriding refusal of any finality, the endless stream of updated editions of each book, and the overlaps between all the streams of books. Jencks’ animated ‘trees’ never simply appear inside books. Rather, they pass through them, transforming the polemic as they evolve, as if twisting the argument into new shapes on their way through. The latest version of the ‘turbulent blob-diagram’ supposedly shows the ‘competitive drama, a dynamic and turbulent flow of ideas, social movements, technical forces and individuals all jockeying for position’ without taking sides, since any apparent victory in the battle ‘rarely last for more than five years and usually for not more than two’.33 But of course, once again, the diagram is itself a side.

In that sense Jencks was always an agent of the Post-Modern and the seventh edition of his book on Post-Modern Architecture in 2002 – retitled The New Paradigm in Architecture: The Language of Postmodernism – presented yet another biomorphic chart, stretching from 1960 to 2000. The drawing was now called ‘Post-Modern Evolution – Evolutionary Tree’.34 Post-Modern was finally both a label within the chart and the label of the chart, with BIOMORPHIC recast as a Post-Modern growth. The rippling landscape has absorbed even more diversity and detail with a multi-coloured hierarchy of labels. Five hundred buildings are mapped onto a plethora of trends to insist once again that the Post-Modern is paradoxically unified by its relentless pluralism. The new diagram would appear in a number of books before being extended to cover another decade in 2011 – with Jencks saying it would still need to at least double in size to accommodate the parallel evolution of Modern, Late-Modern, and Traditional.35 The blobby drawing that seemed to grow when looked at, fed by the desire to visualise everything, was unambiguously in control of the historian who had to constantly tend it like a harried gardener.

As the countless revised editions of the books that Jencks affectionately referred to as his ‘evolvotomes’ kept coming, the evolutionary tree inevitably kept mutating and devouring more names, as if to multiply the very sense of multiplicity. Even the language used to describe the diagram steadily multiplied. The six horizontal pulsations demarcating the evolution of architectural species were variously referred to as ‘branches’, ‘strands’, ‘bands’, ‘streams’, ‘composite rivers’, ‘waves’, ‘fibrous bundles’, ‘strange attractors’, and ‘attractor basins’. The permanently unstable drawing defied any singular description. Yet Jencks never stopped calling it an ‘evolutionary tree’, even it was an anti-tree from the beginning, polemically opposing the tradition of images of evolution as a single trunk that keeps subdividing into ever finer branches with successive mutations, and mutations of those mutations.

The drawing is always about competition, as Jencks insisted in 2015: ‘My diagrams and evolutionary trees of Late, Neo and Postmodernism have never featured less than six streams to each of these large composite rivers, making 12 to 18 competitors at any one time. The agitated blobs of these diagrams show the turbulence of mini-movements vying as fish in a river.’36 Yet it is precisely not about the survival of the fittest. Real biodiversity of parallel experiments means there is no universal over-arching framework to judge one approach as more viable than others and no tendency ever completely disappears. Architectural species keep returning from their apparent death. If the tree drawing is a kind of plant, it is more like a vine, growing horizontally on a hidden frame with a lot of intertwining. No growth is more important than any other and there is no sense of overall advancement. In all the waxing and waning, it is the drawing itself that survives by relentlessly digesting the field.

Other versions had meanwhile appeared with pictures of architects and buildings rather than names, as in a 1986 special issue of the Japanese magazine A+U devoted to Jencks that stretched the two 1980 drawings up to 1985 in dramatic side-by-side fold-outs of the Late-Modern and Post-Modern trees.37 The evolutionary tree technique was also extended to map other territories such as seventeenth- and eighteenth- century Baroque and Post-Modernism in art since the 1960s.38 Periodic articles addressed this use of the biological concept of evolution in architecture and defended the evolutionary tree drawings in the absence of enemies. The defence was symptomatically offered outside the books that the drawings orchestrated. After all, the drawings had an independent life and their whole point was to appear self-explanatory, requiring only a couple of sentences of framing at most when deployed within a book. Yet their elaborate defence outside the books suggests otherwise. The supposed polemical clarity of the drawings paradoxically required its own polemic. Sometimes even this polemic is repeated with minor transformations in a kind of sustained campaign that gets more detailed with time.39 The most extended defence was offered in yet another AD publication of 2010.40 Jencks argued that the original attempt to visualise historiographic inclusiveness with a tree drawing forty years earlier had been provoked by his 1969 study of the systematic biases and omissions in the work of around twenty of the most influential historians of Modern Architecture, including his advisor Banham. The study was published as the essay ‘History as Myth’ before it became the first chapter of the PhD thesis.41 Architectural historians were the first species to be placed in a chart documenting the space between sets of binaries. Exposing the ‘hidden pluralisms’ of seemingly monolithic Modern Architecture called for a counter-historiography, a post-judgemental environmental paradigm.

Ten years earlier, Banham’s PhD thesis had famously done something similar with the systematic omissions of his own advisor, exposing the ‘zone of silence’ in Pevsner’s influential linear narrative that acted as if Expressionism and Futurism had never happened, and calling for their restoration in the official ‘family-tree’. Diversifying the ‘genealogy’ of modern architecture would transform the sense of what it was and what it could or should become in the age of a whole new generation of technologies, synthetic materials, systems, computers, television, gadgets, chemicals, and psychedelic drugs. Jencks was a self-conscious mutation of Banham, who was the first historian of modern architecture to take an explicitly environmental and biological turn, even turning to the question of mutation to imagine a likely future for the field. Banham’s call for a history of the immediate future, taken up so enthusiastically by Jencks, had even pointed to ‘the New Biology’ as the most likely candidate for changing the direction of architecture – using recent discoveries about genetic mutation and the ability of an organism to affect its own constitution and environment as his own basis for extrapolating transformations in the architectural field.42 In the very years that Jencks was writing his thesis, Banham was publicising and collaborating on inflatable blobby architecture that flexed ‘like a living organism’ – even portraying himself as the naked occupant of such bubbles and making TV programmes within them.43 The genetic twist of Jencks was to turn architectural discourse itself into a single pulsating blobby interior that could consume us all, only to finally be happily eaten by the diagram that invented him.