Evolutionary Architecture Mark Lomas · Nature's architecture is hexagonal, spherical, triangular or tetrahedral. Right-angles rarely occur in natural forms. Rectilinear is the architecture

Evolutionary Architecture. Mark Lomas. University of Westminster Student Dissertation 2009.

University of Westminster

Course : Bsc (Hons) Architectural TechnologySchool of Architecture and the Built Environment

(SABE)

4CSS621 Individual ProjectStudent ID : W10711488

Word Count : 9253

Evolutionary Architecture by

Mark Lomas

(April 2009)

“At the dawn of a post-digital, Biological Century, this report investigates Evolutionary Biology as a possible model for sustainable architecture by reviewing key mechanisms and scientific advances, eg. in nanotechnology and biotechnology, with regard to an architecture and engineering context. “

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Evolutionary Architecture

Contents :

1. Abstract

2. IntroductionWhy a biological approach to architecture?What is Natural Architecture?

3. Science and Architecture In Parallel Evolution The Golden/Divine Proportion Fibonacci SequencesSpecialisation and DivergenceArchitecture and Science on Equal Terms

4. Towards a Scientific Architecture

5. FormExample – Termite MoundOther Natural FormsPhysical Factors Influencing Form

6. MaterialsIntroductionExample – NacreEmergent Materials

MetalsBiopolymersConcreteEmergent Composites

Nanomaterials

7. Structural GeometrySpherical/Hexagonal vs.Rectilinear GeometryBifurcation & RecursionPhyllotaxisLogarithmic Spirals

8. ProcessNanotechnology

Protein EngineeringAutomated Molecular EngineeringArtificial Intelligence (AI)

9. Summary

ReferencesBibliographyIllustration Credits

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AbstractAt the dawn of a post-digital, Biological Century, this report investigates Evolutionary Biology as a possible model for sustainable architecture by reviewing key mechanisms and scientific advances, eg. in nanotechnology and biotechnology, with regard to an architecture and engineering context.

By making broad biological, chemical and physical concepts accessible to the non-scientist, it focusses on Spider Silk, Nacre, and Termite Mounds as examples of structural, material, formal and procedural inspiration and opportunity for architects and designers.

By describing some of the evolutionary and algorithmic processes underlying natural forms and structures, connections are made with formal and 'primitive' architectures in order to ask whether there are underlying physical/mathematical or even philosophical reasons for a natural geometry based on objective proportions and relationships. Whereas the Golden Proportion and Fibonacci sequences have long been known, and applied anthropometrically by figures ranging from Vitruvius to Le Corbusier, their emergence at micro-, nano- and fractal scales suggests their importance in any algorithmic, emergent or parametric architecture which might follow from nanotechnology and biotechnology in the coming years.

Like Nature itself, this model for a new type of 'Biotecture' will be algorithmic, optimally efficient and without sentiment. Will its evolution owe more to Darwin, to Crick and Watson, than to Palladio or Le Corbusier? A history of architectural progress in this context discusses the separation of architecture from engineering, science from art, in order to consider who is best placed to implement this Biotecture. Architect? Engineer? Biologist ? Could a natural, scientific architecture evolve from Modernism, or will the two disciplines merely share a common ancestor in the Renaissance ?

It has long been the aim of scientists to synthesise a material as strong as spider-silk, and this is now a possibility. Nacre, a highly brittle layer in a supremely tough layered composite material in the outer shell of certain molluscs, has recently been grown

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artificially. Biological sciences have come to the fore since the discovery of the structure of DNA and the development of tools to map genomes, and whereas architecture and engineering have always been able to mimic nature, it is now possible for humankind to restructure the very building blocks of life – to re-design Nature.

Just as breakthroughs in steel manufacturing revolutionised construction in the 19th

Century, what are the possible paradigm-shifts that might affect construction in this bio-centred future? Could nanotechnology and biotechnology point to a more sustainable future, or can architecture move forward by looking backwards to less intensive forms of technology ?

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2. Introduction

Why a biological approach to architecture ? :Buildings are intensive and unsustainable systems, concentrating massive amounts of energy into their construction, maintenance and running. In the UK, buildings consume

45% of total UK energy consumption1. And yet, for all this power and expended energy,

and with all our technology, hi-tensile steel cannot match spider-silk for specific strength; our most powerful solar panel is no match for a simple leaf in terms of overall energy-efficiency. Photosynthesis in green plants captures approximately 2 x 1023 J of energy pa or 4% of total sunlight available.1

In this century, population growth, energy shortages, water shortages and global climate change are fuelling the need to look again at mankind's place within the ecosystems that we now have the technological power to destroy. James Lovelock's Gaia Theory describes the Earth as “A complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet.2” There is now a wide consensus that this fragile feedback system is in danger of collapse.

Schumacher states that “Modern man does not experience himself as a part of nature but as an outside force destined to dominate and conquer it. He even talks of a battle with nature, forgetting that, if he won the battle, he would find himself on the losing side.3”

If there is one over-arching reason as to why mankind's existence is now threatened, it is perhaps in the linear nature of his consumption of energy and its consequent production of pollution. Because “energy tends to dissipate and organised systems drift inevitably towards entropy, or chaos,2” man's downfall appears inevitable. However, there is no pollution in nature : the waste products of one organism provide an ecological niche for another, and “in seeming violation of that law, biological systems tend to become

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increasingly complex and efficient.4”

The simple decision to see ourselves within, and dependent upon, these natural systems may yet prevent our fall from grace. By modelling our technology and systems on the superior efficiencies of natural processes may provide the best inspiration for our redemption.

Nature builds with what is available, recycles without mercy, and is the ultimate in energy-efficiency and fitness for purpose. Darwin's conclusion to the Origin of Species provides a profound sense of hope, reminding us that “From so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved5.” But can technology ever hope to approach the efficiency and elegance of natural processes? If so, what processes, what tools will we need to develop ? Where do we find inspiration and precedence for a natural, biological architecture ?

What is Natural Architecture?Gaining technological inspiration from nature is not a new concept. Biomorphism is an ageless design methodology – mankind has always looked to nature for examples of how to build, and from Plato to Frei Otto some of history's most influential designers and thinkers have drawn inspiration from natural forms, processes and materials. Democritus said in 400BCE, “We learn important things from imitating animals. We are apprentices of the spider, imitating her in the task of weaving and confecting clothing. We learn from the swallows how to construct homes, and we learn to sing from both the lark and the swan.”6 Nature's architecture is hexagonal, spherical, triangular or tetrahedral. Right-angles rarely occur in natural forms. Rectilinear is the architecture of power, subservience, hubris, a symbol of decadent, 'rise-and-fall' civilisations that, throughout history, have enslaved and expanded outwards to fuel their exponential hunger for energy. The architecture of nomadic and 'primitive' cultures is often circular, built from local biomaterials, ephemeral yet timeless. There are inner geometries in the way Nature builds – Golden Proportions, Fibonacci sequences, fractals, DNA's double helix – and science may, through studying

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natural structures and materials, point the way to more energy-efficient construction algorithms.

The development of domed structures provides a fitting example of a biological form which has been developed and improved as an integral element of architecture over 2000 years.

It is a mathematical truth that a sphere contains the greatest possible volume for a given surface area. Whilst perfect spheres rarely occur in nature (Thompson) because of unbalanced external forces, domes are nevertheless an example of a biomorphic form which holds significant symbolism for many human civilisations, and their evolution deserves consideration as an example of 'natural architecture', of architecture and science proceeding hand-in-hand.

i. The Pantheonii. Hagia Sophiaiii. Santa Maria De La Fioreiv. St.Petersv. St.Paulsvi. Montreal Domevii. Millennium Domeviii. Eden Project

Structures i and ii deal purely with compressive forces, the former through lightweight concrete in a ribbed formation, the latter using secondary domes to resist outward thrust. iii, iv and v perfected the use of iron chains built into the circumferences to resist this thrust. vi. and viii are tensegrity structures, with all forces resolved within the shell, whereas vii relies on steel towers in compression on which to hang the lightweight shell from a networkof tensile cables. viii uses such lightweight ETFE cladding that this is said to weigh less than the air it contains.

A scientific approach to architecture has, therefore, provided mankind with some of our

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most durable, elegant and inspiring structures. And yet, how many of these domes were built by 'architects' in the modern sense of the term ? At what point in history did art diverge from the science of building ?

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3. Science and ArchitectureArchitecture was always at the cutting edge of each age's and civilisation's technological/scientific progress. At some point, the two disciplines diverged, to a point now where the latest biotechnological breakthrough might baffle the architect, and the scientist might find the conceptual aspects of architecture no more relevant than 'angels dancing on the head of a pin.' In order to move forward, it is perhaps instructive to study the historical relationship between architecture and science.

Science & Architecture in Parallel Evolution:Architecture, in the sense of “frozen music,”7 is far more than the sum of its scientific and technological parts. However, long before the αρχιτέκτων evolved from forgotten Master Carpenter to famous Artist, mankind was creating noble, sublime architecture embodying all the cultural, artistic and technological wisdom available to him in any particular age.

Classical Greece gave us the Parthenon (447-436BC) and Rome the Pantheon (118-128AD), but only after other civilisations - eg. Khorsabad, Babylon, Persia, Egypt, India - had developed their own sophisticated architectural legacies : The Palace of Sargon II (722-705BC); The Ishtar Gate (605-561BC); The Palace of Persepolis (begun 518BC); The Great Pyramids of Giza (c.2600BC); The Great Stupa at Sanchi (273-236BC).8

5000 years ago, before even the Pyramids, the Passage Tomb at Newgrange, Ireland was constructed. Not only did this involve the remarkable technological feat of transporting and erecting 200,000 tonnes of stone, but also Newgrange marked the Winter Solstice with astonishing accuracy. The structure itself was designed as a massive scientific instrument.

Such examples were built by societies with the economic wherewithal, power structures or religious faith to expend massive amounts of energy on visionary feats of engineering. Many stand, however, as monuments to civilisations and societies that proved, ultimately,

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to be unsustainable.

Nonetheless, the marriage of architecture with a 'scientific edge' is therefore long-established, and the examples of domed structures above demonstrate this symbiosis.

Meanwhile, man has been housing himself more modestly for thousands of years. Even before the progression from hunter-gatherer to farmer, there developed a wealth of vernacular buildings that one might call 'natural architecture'. Using mud, skins, rocks, sticks, grass or snow, numerous vernacular types were developed, from the Mongols' yurts to the Bedouins' sumptuous tents and the Inuits' igloos. Often, the form is domed, or at least circular in plan, whether the building is intended for mobility (eg. a yurt) or permanence (eg. a Dogon hut). Neanderthal shelters, made of mammoth bones and animal skins, discovered in Ukraine, have been dated as 40,000 years old.9 Their domed form is dictated by the shapes and properties of the biomaterials used and by the external forces applied (wind, rain, snow etc.), all of which is echoed both in the monumental domes above and in our age's most hi-tech tents.

These 'primitive' structural forms invariably represent an evolutionary process of improvement over time; economical and apt use of materials; a structural- and energy-efficiency and a 'fitness for purpose.' Many have survived the ages, whilst empires and civilisations have crumbled to dust. Evolution is a recurrent theme in this search for a natural architecture.

Much of this 'instinctive' adaptation of form and structure to physical forces had been understood and improved upon by the Classical civilisations. Greek and Roman knowledge was almost lost in the West during the Dark Ages, but the 'memes'10 survived, and were passed on, like DNA, along with their own major leaps in scientific understanding, by Islamic/Arabic scholars.

By the time of the Renaissance, this ancient knowledge had been revived and extended,

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forming solid foundations for our later science and architecture. While individual architects such as Brunelleschi, Alberti and Palladio came to be credited for their works, there was still little distinction between the architectural, artistic and engineering aspects of a building project. The architect was both artist and scientist, creating new technology or researching ancient knowledge in order to realise his vision.

Drawing on rules of proportion learnt from Ancient Greece and Rome, but which were employed earlier in the construction of the Pyramids and perfected in the high Gothic Cathedrals of the 11th and 12th Centuries, it was apparent, for example to Leonardo Da Vinci, that the Divine Proportion and the mathematical relationships discovered by Fibonacci (Leonardo Da Pisa) exist also in many natural botanic forms. Da Vinci famously developed 'Vitruvian Man' from the Ancient Roman writer's 'De Architectura', itself influenced by the assertion by Heraclitus (540-480BC) that “Man is the measure of all things.” 11

The Golden/Divine Proportion :As has been shown, there are consistent underlying themes carried over in architecture from early history to present day. Instinctively, human civilisations chose certain proportions in buildings, paintings, sculpture and even music that appeared more 'pleasing', relating proportion initially to measurements of human form, then discovering similar relationships throughout nature on the meso-scale that they were able to observe.

This relationship came to be known as the Golden or Divine Proportion, represented by the Greek symbol Φ (Phi). Φ = (1+√5)/2 = 1.618033988.... and is a Transcendental number12 similar to π (Pi) - their decimal expansions contain no repeating sequences of numbers and do not terminate.

Hemenway writes, “Its harmony is apparent in the principles of design that nature uses to give us patterns in plants, shells, the wind, and the stars. The regenerative principle shows up in shapes and solids that form the basis of everything from DNA to to the contour of the

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Universe. Balance is found in the spiral in our inner ear and is reflected in the unfurling shape of the human embryo that hurls us into existence.”13

Fibonacci Sequences :Fibonacci's numerical sequence (0,1,1,2,3,5,8,13,21...), so ubiquitous in nature, is closely related to Φ. The relationship between any pair of consecutive Fibonacci numbers approaches Φ as the numbers increase in value. As will be seen in later sections, Fibonacci sequences are being discovered at macro, micro and now nano-scales that those early civilisations could scarcely have imagined.

Specialisation and Divergence :But where, or when, did architecture, engineering and science diverge?

The architecture of the 19th Century was the product of the Engineering Age, where structural achievement took precedence over the aesthetics form. A discussion of the exact point at which architecture and engineering diverged would fill a volume in its own right, but it is clear that, by the time I.K.Brunel was at the height of his career, he was delegating the 'lesser' considerations of architecture.

Modernism, eschewing ornament14 presented itself as a rational, scientific foundation for the machine age. Nevertheless, it absorbed the ancient, near-mystical rules of proportion so heavily connected with the florid botanic forms that architects such as Adolf Loos despised and condemned. Far from breaking with the past, Le Corbusier modelled his own 'Modulor' system of proportion on rules encompassing the Golden Section/Divine Proportion and Fibonacci sequences.

Other architects of the modern age took a more open-minded approach to ornament and to biomorphic form. Louis Sullivan developed an algorithmic process of ornamentation based on plant forms. Frank Lloyd Wright promoted an 'Organic Architecture' whose forms were

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inspired by natural phenomena, albeit perhaps more geological than botanical. Antoni Gaudi developed curving, sinuous organic forms, calculating the compressive forces on vaults, arches and curved columns from the parabolas formed by chains in tension in an inverted form of his model. Oscar Niemeyer sculpted dogmatic modernist rectilinearity into sweeping, sensuous curves. Eero Saarinen “made use of what later became known as 'technology transfer', with components and materials used in automotive design – notably neoprene gaskets that were to become an important feature of High-tech architecture 20 years on.”1 However, it is clear that, by this period, the science was an external factor in the design process, playing a secondary role to architectural and sculptural form.

In broad terms, therefore, mainstream 20th Century architecture and design had become largely a matter of form and function. But function, to the Modernist, Brutalist or Post-Modernist, was a world away from Sullivan's original inspiration for his famous phrase, “Whether it be the sweeping eagle in his flight, or the open apple-blossom, the toiling work-horse, the blithe swan, the branching oak, the winding stream at its base, the drifting clouds, over all the coursing sun, form ever follows function, and this is the law.” Architecture's very touchstones - Palladio's cubes and double cubes; Jeanneret's horizontality; Miesian rectilinearity – fail, or even refuse, to engage with natural form, or with more than the most superficial of functionality. Overall, one wonders what effect that most influential of architects might have had on the blighted council tower blocks of the 1950's and 60's if he had prompted us to imagine the “organisme à habiter.”

Architecture and Science on Equal Terms :The trend, perhaps for 200 years, had therefore been a divergence of architecture from engineering, art from science. Notable exceptions, however, pursued architecture and science on equal terms.

Richard Buckminster Fuller developed the geodesic dome, the Dymaxion House and a wealth of inventions and processes largely inspired by his observations of natural

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processes. However, without the architectural or engineering credentials, and with a propensity towards self-mythology2 , his bizarre “tendency to write in a complex jargon, in many cases making use of terms and phrases he himself has coined”3 kept his works on Synergy and spherical geometry largely on the fringes of both disciplines. Latterly, notwithstanding criticisms of Fuller for “arriving incoherently at logical conclusions,'”4 the discovery of Carbon 605 and its resemblance to Fuller's geodesic structures has given new credence and attention to Fuller's vast range of work.

“Frei Otto's career bears a similarity to Buckminster Fuller's: both were concerned with space frames and structural efficiency, and both experimented with inflatable buildings.”6 In contrast, however, Otto “pioneered advances in structural mathematics and civil engineering”7 and has taken an academic approach to the design of tensile and pneumatic structures, creating fluid, natural forms inspired by both vernacular/primitive architecture and natural forms and processes. Claimed and lauded by both architectural and engineering professions, his work truly marries architecture with science.

This theme of form following material and structural concerns is central to the idea of natural architecture in the context of this dissertation, albeit with the added dimension of evolutionary biology informing the investigation of nature as process.

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4. Towards a Scientific Architecture“To mimic nature from the outside by externalising and copying what the eye sees is limiting. Better to look inside and find the interior motif that builds outwards again.”15

The main theme of this report concerns how architecture and construction may evolve in the light of new discoveries in science, particularly within biotechnology and nanotechnology. Between these two cutting-edge disciplines, there is much common ground – for example Drexler (1990), in describing the fundamental processes in nanotechnology (cellular machines) draws heavily on the language of Darwin and evolutionary theory. “The history of life is the history of an arms race based on molecular machinery. Today, as this race approaches a new and swifter phase, we need to be sure we understand just how deeply rooted evolution is. In a time when the idea of biological evolution is often slighted in the schools and sometimes attacked, we should remember that the supporting evidence is as solid as rock and as common as cells.”8

To Drexler, evolution is not simply a metaphor. “Mutation and selection of genes has, through long ages, filled the world with grass and trees, with insects, fish, and people. More recently, other things have appeared and multiplied – tools, houses, aircraft, and computers. And like the lifeless RNA molecules, this hardware has evolved.”9

Accepting this “Evolving Technology,”10 Drexler goes further. “Technology development is much more evolutionary and much less revolutionary or breakthrough-oriented than most people imagine,”11 because “Generation and testing of alternatives is synonymous with variation and selection.”

The following sections on Form, Materials, Structural Geometry and Process all concern the mechanisms by which nature, through the process of evolution, or natural selection, creates physical form.

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5. FormAs noted earlier, 20th Century design was dominated by the mantra “form follows function.” Despite its meaning, it is clear from the construction of the phrase itself that 'Form' is the primary concern. Form is architecture's purpose.

The purpose of evolution, however, is not form. Form in nature is merely the by-product of a process whose purpose is to pass on genetic information. Form evolves and is a niche, an opportunity in time. As external factors vary, so the form varies to suit. In short, form evolves but physical laws remain constant. The basis of any algorithmic or scientific architecture which seeks to mimic nature's efficiency must first differentiate these scientific constants from the artistic and cultural variables that differentiate architecture from evolution.

Thus, D'Arcy Wentworth Thompson's 'On Growth and Form' became a touchstone for those seeking a scientific basis for natural forms. Thompson explained the factors shaping natural forms in terms of diagrams of forces; scale; surface area : volume relationships; surface tension and so on.

Thompson showed that physical form is indeed subordinate to other factors. “Morphology is not only a study of material things and of the forms of material things, but has its dynamical aspect, under which we deal with the interpretation, in terms of force, of the operations of Energy.”16

Form, therefore, follows a process of complex inter-relationships between material properties, physical constants, external environmental variables and, above all, energy.

Form follows process, and form follows energy.

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Example : Termite MoundAn example of a natural form which illustrates this point is the Termite Mound, which has evolved to maintain constant internal temperature and humidity levels in the extremes of tropical and subtropical climates.There are around 2600 taxonomically known species of this social insect, and colonies can

range in size from a few hundred to several million individual termites comprising a Queen, Workers and Soldiers. Some build their nests in trees, some underground, but the most notable are the above-ground mounds built using soil, mud, chewed wood cellulose and the insects' faeces. The saliva and gastric juices of the termites bind this mixture into a material which is exceptionally hard and durable.

Depending on the prevailing climate, the mounds extend up to 9 metres high, and can resemble mushrooms or towers. In addition to containing chambers for a range of purposes, the mounds have evolved sophisticated mechanisms for rainwater collection, ventilation and O2/CO2 balance, solar gain/shading through orientation, and humidity control. In arid regions, the termites may dig up to 40m depth to bring water by evaporation up into the mound to increase humidity. Some species symbiotically 'farm' particular fungi which, as well as providing nutrition, produce heat and help to maintain the required high humidity levels.

In an arid climate with temperature fluctuations of up to 30oC, it has been shown that the termite mound is capable of maintaining within +/- 1oC the ideal internal temperature of 29oC, whilst also achieving near 100% stable relative humidity.17

A by-product of the deep excavations by termites is that they bring up 'geological samples' from deep underground.18

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Other Natural FormsOther species build. The nests of birds show huge variety in form, and ingenuity in the use of natural materials. Many birds build with twigs, others with mud and saliva, but perhaps one of the most ingenious nest forms is that of the Tailor Bird (Illustration....). The bird sews together two palm leaves, using plant fibres, cotton or spider webs to join them.

Termites are also not the only insects to build. Some species of wasp build intricate, delicate nests from a paper pulp that they make by chewing wood cellulose. Their saliva acts in similar fashion to that of termites, binding the cellulose into a strong building material. (Illustration...)

Honeybees have evolved wax-secreting glands, and therefore build with this. Their arrays of hexagonal honeycomb cells form a hive which has 'environmental control' mechanisms similar to those of termite mounds.

Physical Factors Influencing FormThe examples illustrate the earlier point that naturally evolved forms are the product of materials, processes and physical laws. Underlying all evolutionary transactions is an energy cost, and the millions of generations of millions of species over evolutionary time have optimised these energy transactions to high efficiencies such as those shown in termite mounds and honeycombs.

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It is precisely because of these physical principles that nature, as shown in illustrations... to ...., often tends towards evolved forms based on hexagons. Wasps' nests and bees' combs are examples of 'built' forms, but hexagonal networks are also visible in radiolarian skeletons, turtle shells, dragonfly wings and compound eyes. At the microscopic scale, they appear in natural forms as diverse as knotweed pollen, skeletal muscle, marram grass, charcoal. However, hexagons are formed spontaneously in the non-living world, and are apparent in forms ranging from snowflakes and silicon crystals to basalt columns.

Many of the physical laws affecting organic form are general engineering principles of stress, strain, elasticity, fracture mechanics and fluid dynamics. The general factors were outlined by Thompson in his 1917 work, and treated in more depth later by Wainwright et al.19

Hasegawa's explanation of the mechanism by which bees form hexagonal, rather than circular, cells also suggests why hexagons are so common. “...didn't it start with an array of cylindrical cells with initially circular cross-sections? Down the line... just like Thompson's explanation of soap bubbles, the shared walls of adjacent cylinders begin to transform into a composition of hexagonal cylinders.”20

Natural form seeks, and finds, a balance between, on the one hand, forces applied by adjacent cells, and on the other, the requirement for “wax economy.”

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Illustration 1: Hexagonal array - silicon crystal

Illustration 2: Hexagonal array - skeletal muscle


6. MaterialsIntroductionIn contrast with architecture, manufacturers spend heavily on research – not only into the development of products, but also into market trends. The latest product advances can provide a powerful insight into future trends and the possibilities for building design. Perhaps also there is no better model of a man-made evolutionary process than the development and manufacture of materials, of products, where only the fittest survive.

Some of these evolutionary advances are simply improvements on long-established materials. Others, however, take us into new realms. Many of the emergent materials mimic the properties of natural and biological materials – sometimes through conscious research, but in other cases it is clear that the more technology optimises man-made materials, the more they come to resemble natural materials.

The benefits to engineering of materials with more 'biological' properties would be immense. Gordon argues that “the engineer could not contrive a steam engine out of bladders and membranes and flexible tubes. So he was compelled to evolve from metals, by mechanical means, movements which an animal might have achieved more simply and perhaps with less weight.”21

Many bio-materials are composites of other more basic components, evolved to withstand, “with a maximum of efficiency and at a minimum of cost,”22 the external forces to which they are subjected. Composites are also a mainstay of modern construction, from reinforced concrete and fibre-cement products to insulated man-made boards. Artificial Nacre is an example of a composite explicitly modelled on a natural material in order to benefit from such maximum efficiency.

Example : Nacre

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Nacre, or Mother of Pearl, is a natural composite occurring as an inner layer in the shells of certain molluscs.

It is of interest due to its exceptional toughness. It comprises hexagonal platelets of aragonite, which is a polymorph of Calcium Cabonate (CaCO3). These thin lamellae of strong but brittle ceramic material are interleaved with layers of elastic biopolymers (eg. chitin and lustrin) in a bonded matrix.

Its toughness (ie. resistance to the propagation of cracks) results both from this combination of brittle ceramic and elastic layers and from variations in the lengths of the platelets. While it is easy to fracture a single layer of the ceramic, the crack cannot propagate beyond the next elastic layer – the impact energy is dissipated across this layer's greater surface area. More energy is then required to force a crack in the next ceramic layer, and so on.

Deville et al. have developed a method for synthesising a metal ceramic artificial nacre,23 its primary application being as artificial bone in orthopaedic implants. However, many construction materials are limited not by their strength but by their toughness, and a lightweight yet tough material modelled on nacre's complex microstructure would undoubtedly find applications within architecture.

This artificial material's debt to nature is not lost on its developers. “We are half a micron away from mimicking nature,” said one of the researchers.24

Emergent Materials

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Illustration 3: Natural Nacre

Illustration 4: Artificial metal ceramic Nacre


Fernandez, in 'Material Architecture', provides an accessible and focussed review of materials, along with the wider issues of their use and acceptance within the design and procurement of buildings. A brief outline is given below of advances in materials, with an emphasis on those inspired by, or mimicking, natural and biological materials.

i. Metals :Fernandez highlights superplastic alloys, shape memory alloys and metal matrix composites as having applications in architecture, along with ceramic-metal oxide fibres in textiles, and spheroidal graphite cast iron. A micrograph of a Hollow Stainless Steel Assembly shows a close resemblance to the structure of eggshell.

ii. Biopolymers :Spider silk has fascinated mankind since classical times because of its unique mechanical properties. Weight for weight, it is “5 times stronger than steel... 30 times more flexible than nylon... [and] can absorb three times the impact force of Kevlar without breaking.”25

The silk is extruded from hundreds of tubes comprising the spinneret. Its elasticity is as a result of the geometry of H-bonds between the protein molecules26, which act as molecular springs.

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Illustration 5: HSSA Micrograph

Illustration 6: Eggshell


Mukhopadhyay and Sakthivel report that a recombinant, or genetically engineered, spider silk with the trade name 'BioSteel' has been developed for medical, military and industrial markets.27 They also propose that spider silk will find applications in impact and tear-proof textiles, which they refer to as “Techno-silks.”Keten and Buehler applied the thermodynamic approach of fracture mechanics, illustrated in the nacre example above, to explain the properties of spider silk. They see a broader scope for their explanation of the H-bond mechanism, however, envisaging that it will advance the ability to “design new materials based on proteins.”28

Advances are also being made in biodegradable polymers from natural (non-fossil) sources. Genetically modified bacteria turn glucose from corn starch into polyhydroxyalkanoate (PHA). This material's mechanical properties are superior to those of polylactic acid (PLA)-based bioplastics, and may therefore eventually find applications in construction.29

iii. Concrete :Three main developments in concrete, though not directly nature-inspired, are nevertheless important steps towards more sustainable forms of this important material :

Novacem has developed a concrete based on magnesium silicates which absorbs carbon dioxide on curing, making it carbon-negative.30

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Illustration 7: Spider's spinnerets producing silk

Illustration 8: Spider silk under extension


TecEco, on the other hand, is promoting magnesium carbonate concrete to similarly sequester CO2.31

Constantz has meanwhile developed a process to sequester the CO2 from a gas-fired power station, by reacting the CO2 with magnesium and calcium solutions in sea water.32

Other developments in concrete are seeing the use of carbon fibres or nanotubes as reinforcement. These have the added property of electrical conductivity, leading to 'smart concrete' – as loading on the structure varies, the resistance of the electrical circuit varies too, enabling monitoring of the structural integrity of sensitive structures such as bridges.33

iv. Emergent composites :As illlustrated by the example of nacre above, the combinations of different materials for improvements in their overall properties is ubiquitous across both nature and the artificial world. We are accustomed to the use of steel and glass imparting their superior tensile strength to, respectively, concrete and polymers. Fernandez states that “New composites are arising constantly,”34 and lists the following as amongst the most noteworthy developments : Metal Matrix Composites (MMC); Smart fibre reinforced polymers; Next generation fibre-reinforced composites; Snap joint technology for composite structures; nanomaterials (see below) and biomimetic materials.

NanomaterialsThere are various official definitions of nanotechnology. The German Federal Ministry of Education and Research (BMBF) provides a typical summary: “Nanotechnology refers to the creation, investigation, and application of structures, molecular materials, internal interfaces or surfaces with at least one critical dimension or with manufacturing tolerances of (typically) less than 100 nanometres.”35

Despite the 'futuristic' image of nanotechnology, there are already nanomaterials on the

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market and in use in architecture and construction. Materials have been developed with diverse properties : self-cleaning; air-purifying; anti-fogging; UV protection; solar protection; Fire-proofing; anti-graffiti; anti-reflective; anti-bacterial; anti-fingerprint. There are also nanogels and aerogels, and Phase Change Materials (PCM's).

Some of these products result directly from research into biological processes – for example the Lotus Effect was developed by botanist Wilhelm Barthlott from his research into super-

hydrophobic of certain plant species.36

Other examples apply the latest manufacturing science to ancient knowledge. Photocatalytic antibacterial coatings, in use in hospitals, use silver nanoparticles to destroy bacteria by the diffusion of silver ions. Silver's anti-microbial properties have been known for over 3000 years, but since nanoparticles provide an increase of surface area to volume, ions are emitted in greater quantities and the effect is greatly increased.37

Carbon, in its 3 main allotropic forms – diamond, graphite and now the Fullerenes, will play a massive part in any future technology.

Not yet at market, but with massive potential once their mass-manufacture is achieved at reasonable cost, are Carbon

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Illustration 9: Aerogel

Illustration 10: Carbon allotropes


Nanotubes. Emerging from the discovery of Carbon 60, Buckminsterfullerene, these materials have a tensile strength far in excess of steel, yet they are lighter and flexible. They are highly conductive, and applications will range from electronics to concrete re-inforcement.38

As electronics reaches the limits of silicon technology, the superconducting properties of carbon may come to the fore, and “the future of computing could lie in shavings of carbon just one atom thick, a material known as graphene.”39

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7. Structural Geometry :This report seeks to identify mechanisms by which natural forms come into being through the influence of evolution. In the sections on Form and Materials it has been shown that nature is capable of incredibly complex 'design', simply in the in-built imperative on organisms to pass on their DNA into the future.

This section discusses three themes that have a bearing on the structure and geometry of natural form : Spherical vs Cartesian Geometry; Bifurcation; and Equiangular Spirals.

Spherical/Hexagonal vs. Rectilinear GeometryIf evolution is seen as a force for developing optimal forms that balance the effects of physical constraints with the energy required to withstand them, then the ubiquity of hexagonal arrays suggests that these are optimal natural forms. Thompson saw this, and from it Buckminster Fuller developed his geodesic domes based on 'tensegrity' and Frei Otto his tensile structures based on the surface tension in soap bubbles, both in a search for an architecture which is both structurally and materially efficient. These principles are therefore well established in architecture, and the concepts have been extended further by architects such as HTA.40

Thompson explained just how hexagonal arrays are formed from the 120o angles between circles, as illustrated in diagram..... but observed that these angles “got rare and scanty notice.”41

Fuller, in his extensive but opaque Synergetics volumes, redressed this balance by devoting much of his attention to 120o and their supplementary 60o angles. He rejected Cartesian 90 degree co-ordinates and saw them as restricting our understanding of reality. His works

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Illustration 11: Hexagon formation


on spherical geometry led him to state that “I have discovered the coordinates of the Universe.”42 Although his theories were unintelligible to the academic world, they nevertheless formed the basis of his work on geodesics and tensegrity structures.

With the discovery of Carbon 60, named Buckminsterfullerene because of its resemblance to Fuller's domes, there is perhaps some vindication of Fuller's non-Cartesian model. Without academically accepted mathematics, Fuller yet succeeded in developing structures that appear widely in 'natural geometry'.

Balmond also has attempted to break free of the rectilinear. Rem Koolhaas writes, “he has destabilized and even toppled a tradition of Cartesian stability – systems that had become ponderous and blatant.”43

Such iconoclasm is apparent, finally, in Lisi's proposed 'Theory of Everything'. A complex pattern based on hexagons, may, according to New Scientist, “reveal the link between gravity and the other fundamental forces of nature.”44

Bifurcation & RecursionThe principles of bifurcation and recursion could be categorised under 'process', rather than as structural or geometric factors. However, they are discussed here because they relate to geometry as discussed above. Cartesian thinking is bound up in the 'DNA' of architecture – in its rectilinear and absolute plans, sections and elevations. It will be shown that an architecture based on evolutionary processes would require a differentapproach to 3-dimensional space.

Dawkins uses recursive branching as a metaphor for the embryonic development of organisms, stating that “all embryos grow by cell division. Cells always split into two daughter cells.”45

Drexler illustrates this more simply. “A cell replicates by copying the parts inside its

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membrane bag, sorting them into two clumps, and then pinching the bag in two.”46

Growth of organisms results, therefore, from a doubling of cells in a simple branching, or bifurcation, algorithm. The diagram illustrates the relationship of each generation of cells to its ancestor. The main trunk branches into 2 branches, and each branch grows 2 sub-branches. The depth of recursion is the number of generations of the algorithm.

This most simple of algorithms, of cells doubling into two separate discrete cells, leads, within few generations, to an exponential increase in daughter, grand-daughter etc. cells. The diagram merely illustrates, for now, a hierarchical or ancestral pattern, not a physical form.

Such simple cells replicate, generating more discrete

versions of themselves until external factors – eg. shortage of resources, better-adapted cells – halt the process.

However, “A major step in evolution was taken when cells that had been produced by successive splittings stuck together instead of going off independently. Higher-order structure could now emerge.”47

Dawkins shows a simple program for generating emergent 2D forms from minor variations in simple measurements such as branch length and branching angle. If it is now imagined that the same diagram shows a complex organism of interconnected cells, it is obvious that the branching cells require no concept of an absolute Cartesian position in space. Each branching is simply growth in a direction relative to the previous branching.

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Illustration 12: Bifurcation


This is an important concept in the understanding of how organisms grow, in comparison with the ways in which we are accustomed to buildings being built. Dawkins sums it up by saying that “... genes always exert their final effects on bodies by means of local

influences on cells, and on the two-way branching patterns of cell division. An animal's genes are never a grand design, a blueprint for the whole body. The genes...are more like a recipe than a blueprint; and a recipe, moreover, that is obeyed not by the developing embryo as a whole, but by each cell or each local cluster of dividing cells.”48

PhyllotaxisFollowing on from branching, a further way in which 'natural geometry' again optimises in terms of energy cost and return is in Phyllotaxis, or the ways in which leaves are arranged on the stems of plants.

Many plants have simple arrangements of leaves in opposite or alternating pairs. Others have whorled leaf patterns. However, those species that have evolved with spiral leaf patterns benefit from a highly perfected optimisation mechanism that Leonardo Da Vinci suggested gave these species an adaptive advantage.

The repeating spiral is described as a fraction of a 360o

rotation around the stem – eg. 1/2 for alternate pairs. Oak has 2/5, while almond and willow are represented by 5/13.The numerator and denominator are, in most cases, a

Fibonacci number and its second successor. The adaptive advantage of evolving as Fibonacci spirals is in the increased exposure that this provides to sunlight and moisture. The higher the Fibonacci ratio, the more complex the arrangement and the less likely that a leaf will obscure others. This phenomenon extends to the arrangement of seed heads, for example the well known spiral patterns in sunflowers.49

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Illustration 13: Phyllotaxis by spiral growth


Logarithmic SpiralsThe spiral leaf patterns described above are amongst many examples of Logarithmic spirals occurring in natural forms.

Logarithmic, equiangular or Golden spirals are a function of the Golden Proportion described in “Science in Architecture' above. Illustration 14 shows graphically how the spiral relates to a Golden Rectangle. As can be seen from Phyllotaxis, they can also be constructed from Fibonacci numbers– the lengths of the sides of squares A,B,C and D are a Fibonacci sequence.

The Nautilus shell in illustration 15 is the classic example, however logarithmic spirals are widespread, from the spiralling arms of galaxies to vortices in fluids. They control the geometry of plants and trees in the effects described above. Fibonacci spirals also define the shape and proportions of DNA. Mollusc shells, however, are the most relevant to the search for natural construction algorithms.

Thompson describes the simple, algorithmic, process by which the many species of mollusc build their protective shells. “In the growth of a shell, we can conceive of no simpler law than this, namely, that it shall widen and lengthen in the same unvarying proportions: and this simplest of laws is that which Nature tends to follow. The shell, like the creature within it, grows in size but does not change its shape.”50

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Illustration 15: Nautilus shellIllustration 14: Logarithmic spiral & relation to Golden Rectangles


Illustration 16 shows a variety of shell types. Thompson shows that simple variations in the angles α, β and γ are sufficient to produce the wide variety of forms.

Wise dismisses as “the repeated skinning of a much-abused cat,”51 Balmond's investigations into spiral equations. Considered merely in relation to architectural form, such spiral geometry might, as Wise suggested in a lecture at University of Westminster, lead merely to snail-shaped architecture. However, as an example of algorithm, their value is more in terms of process than of form.

The main significance here of this process is in 'growth without changing shape', or, as Thompson refers to it, 'continual similarity', even when growth of the shell is 'asymmetric' or the growth of horn, because it grows at one end only, is 'terminal'.

According to Thompson, equiangular spirals are the only mechanism by which this continual similarity can occur in terminal growth.

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Illustration 16: Mollusc shell forms


8. ProcessIt was stated above that 'form follows process.' The examples so far, of a wealth of complex natural phenomena, are all the result of a process – of evolution through natural selection. In the first sections, on the history of architecture and its relationship to science, evolutionary processes were in evidence. The technology of construction progressed through incremental improvements, as successful designs were selected and replicated.

It has been shown that biological systems have evolved that produce materials, forms and processes that mankind cannot match for their overall structural, material and energy efficiency, and that therefore a model based on this evolutionary process would be a major step towards genuinely sustainable construction.

Evolution, then, will be the model for any mechanism of algorithmically-generated architecture. But how do we 'grow' a building ?

NanotechnologyNanotechnology is, to a great extent, rooted in the concepts of evolutionary biology. It offers the facility for eventually combining mankind's most advanced engineering and IT technologies with the types of natural biological processes described earlier. Feynmann's 1959 paper 'Plenty of Room at the Bottom' was influential in promoting the concepts that led to nanotechnology. Feynmann wrote that the principles of physics “do not speak against the possibility of manoeuvring things atom by atom.”52

It was Drexler's influential 'Engines of Creation,' released in 1986, that subsequently helped to sow the seeds for nanotechnology in the public imagination.

Nanotechnology, in Drexler's view, parallels Darwinian evolution in many key areas. And while Drexler is writing of mutation and replication in Darwinian terms, Dawkins is referring to 'molecular machines'.

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Nanotechnology and Artificial Intelligence will, Drexler argues, develop symbiotically, and he uses evolution to argue that this is, to some extent, inevitable, stating that “casual critics also avoid thinking seriously about AI by declaring that we can't possibly build machines smarter than ourselves. They forget what history shows. Our distant, speechless ancestors managed to bring forth entities of greater intelligence through genetic evolution without even thinking about it. But we are thinking about it, and the memes of technology evolve far more swiftly than the genes of biology.”53

A selection of nanomaterials was described in 'Materials', along with a definition of nanotechnology. Those products conform to the definition of 'nano' in their scale, but nanotechnology, in Drexler's vision of the future, is more a matter of process than product. “Machines able to grasp and position individual atoms will be able to build almost anything by bonding the right atoms together in the right patterns.”54

Drexler sees the development of the technology happening in three key fields :

1. Protein EngineeringDifferentiating the biological functions of cells, he refers to proteins as cords, struts, bearings and motors. Biochemists will develop the ability to manipulate these protein motors and bearings so that these will be able to manipulate individual molecules. “For example, they might make an enzyme-like machine which will add carbon atoms to a small spot, layer on layer. If bonded correctly, the atoms will build up to form a fine, flexible diamond fiber having over fifty times as much strength as the same weight of aluminium.”55

As this technology develops, he envisages “programmable protein machines [that] will resemble ribosomes programmed by RNA, or the older generation of automated machine tools programmed by punched tapes.”56

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2. Automated Molecular EngineeringInspired by Feynmann's non-biological approach, but all the while using analogies with biological mechanisms, he suggests that Assemblers, Disassemblers and Replicators will be the key components of an artificial, 'engineering' based approach to the manipulation of molecules.

Universal Assemblers will be the first stage, perhaps built by programmable protein machines. As technology progresses, Disassemblers will be developed with the ability to deconstruct a material or object to analyse its molecular structure. Then Replicators, which are simply a version of Assemblers with the ability to receive instructions from Disassemblers, will be able to recreate copies of the object.

3. Artificial Intelligence (AI)Drexler differentiates between Technical AI and Social AI. He sees advanced Technical AI as a realistic goal, being based on Expert Systems currently developed in medicine, engineering etc.

“At some point, full-fledged automated engineering systems will pull ahead on their own. In parallel, molecular technology will develop and mature, aided by advances in automated engineering. Then assembler-built AI systems will bring still swifter automated engineering, evolving technological ideas at a pace set by systems a million times faster than a human brain.”57

As these three main strands of nanotechnology develop, “The deep-rooted principles of evolutionary change will shape the development of nanotechnology, even as the distinction between hardware and life begins to blur.”58

Applying this process to the construction of buildings, Drexler again uses biological analogies. “Skyscraper construction and the architecture of life suggest a related way to

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construct large objects. Large plants and animals have vascular systems, intricate channels that carry materials to molecular machinery working throughout their tissues. Similarly, after riggers and riveters finish the frame of a skyscraper, the building's “vascular system” - its elevators and corridors, aided by cranes – carry construction materials to workers throughout the interior. Assembly systems could also employ this strategy, first putting up a scaffold and then working throughout its volume, incorporating materials brought through channels from the outside.”59

The 'science fiction' image of nanotechnology, as illustrated in, for example, Virtual Light by William Gibson, is of 'nanobot' assemblers swarming to construct buildings. And it must be admitted that these advanced concepts of nanotechnology are far-fetched, to say nothing of either the dangers inherent in this technology (which are well covered by Drexler) or indeed of the reduction of architecture to a set of algorithms.

However, Drexler's vision in 'Engines of Creation' is consistent and well thought-out. His 1992 book 'Nanosystems' provides a more detailed analysis of the scientific and engineering concepts. Some of the limiting factors surrounding nanotechnology concern the magnified effects of eg. Brownian motion, viscosity, electrostatic charges. These are the challenges for researchers.

Notwithstanding these criticisms, nanomaterials are being incorporated in architecture, and Drexler's vision of nanotechnology, albeit far-fetched, is an inspiration for anyone interested in better, more sustainable buildings.

Incorporating some of the themes discussed in earlier sections on materials and form, Drexler describes a nano-assembled engine :

“Where great strength is needed, the assemblers set to work constructing rods of interlocked fibers of carbon, in its diamond form. From these, they build a lattice tailored to stand up to the expected pattern of stress. Where resistance to heat and corrosion is

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essential (as on many surfaces), they build similar structures of aluminium oxide, in its sapphire form. In places where stress will be low, the assemblers save mass by leaving wider spaces in the lattice.

What is the engine like? Rather than being a massive piece of welded and bolted metal, it is a seamless thing, gemlike. Its empty internal cells, patterned in arrays about a wavelength of light apart, have a side effect: like the pits on a laser disk they diffract light, producing a varied iridescence like that of a fire opal. These empty spaces lighten a structure already made from some of the lightest, strongest materials known. Compared to a modern metal engine, this advanced engine has over 90 percent less mass.”60

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9. SummaryThe aim of this project was to investigate the fundamental mechanisms by which Nature builds material form. This was to identify possibilities, albeit 'futuristic', for an architecture with a scientific, rather than artistic, outlook. An architecture which recognises the sustainability at the heart of natural systems, and can create, therefore, more genuinely, holistically sustainable buildings.

Evolution has shown that, from the simplest of algorithms working over a sufficient number of generations, the most intricate, efficient and pleasing forms are generated and sustained purely by the energy of the Sun. Nature builds from hexagons and spirals. Nature's mechanisms are at work all around, in materials, structure, geometry and form. Most importantly, in process, because form, in this algorithmic future, follows process.

In tracing the parallel evolution, and at some point the divergence, of architecture and science, many of the key 'rules' of architecture are outlined. Much of architectural theory is concerned with proportion, and while Drexler's visions for nano-designed and nano-built architecture may seem far-fetched, an advanced Artificial Intelligence will, no doubt, have the capacity to process proportion and many other 'rules' that are coded into architecture's collective DNA.

Whether or not these concepts reach the construction site, they lurk already in the computers of designers working with parametric and algorithmic software to visualise new architectures. No-one could doubt, seeing the advances in software over the years, that these algorithms are being programmed right now.

As Darwin was well aware as he agonised for more than 20 years over whether to publish 'On the Origin of Species', his theory explained away the need for a 'Designer'. The prospects for nanotechnology, working from a broader palette of components over accelerated timescales, may explain away the existence of architects.

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Documents

Evolutionary Architecture Mark Lomas · Nature's architecture is hexagonal, spherical, triangular or tetrahedral. Right-angles rarely occur in natural forms. Rectilinear is the architecture