Towards homeostatic architecture: simulation of the generative process of a termite mound construction

This report sets out to the theme of the generation of a ‘living’, homeostatic and self-organizing architectural structure. The main research question this project addresses is what innovative techniques of design, construction and materials could prospectively be developed and eventually applied to create and sustain human-made buildings which are mostly adaptive, self-controlled and self-functioning, without option to a vast supply of materials and peripheral services. The hypothesis is that through the implementation of the biological building behaviour of termites, in terms of collective construction mechanisms that are based on environmental stimuli, we could achieve a simulation of the generative process of their adaptive structures, capable to inform in many ways human construction. The essay explicates the development of the 3-dimensional, agent-based simulation of the termite collective construction and analyzes the results, which involve besides physical modelling of the evolved structures. It finally elucidates the potential of this emerging and adaptive architectural performance to be translated to human practice and thus enlighten new ecological engineering and design methodologies

Logistic Constraints on 3D Termite Construction

Abstract. The building behaviour of termites has previously been modelled mathematically in two dimensions. However, physical and logistic constraints were not taken into account in these models. Here, we develop and test a three-dimensional agent-based model of this process that places realistic constraints on the diffusion of pheromones, the movement of termites, and the integrity of the architecture that they construct. The following scenarios are modelled: the use of a pheromone template in the construction of a simple royal chamber, the effect of wind on this process, and the construction of covered pathways. We consider the role of the third dimension and the effect of logistic constraints on termite behaviour and, reciprocally, the structures that they create. For instance, when agents find it difficult to reach some elevated or exterior areas of the growing structure, building proceeds at a reduced rate in these areas, ultimately influencing the range of termite-buildable architectures

Revisiting stigmergy in light of multi-functional, biogenic, termite structures as communication channel

Termite mounds are fascinating because of their intriguing composition of nu- merous geometric shapes and materials. However, little is known about these structures, or of their functionalities. Most research has been on the basic com- position of mounds compared with surrounding soils. There has been some targeted research on the thermoregulation and ventilation of the mounds of a few species of fungi-growing termites, which has generated considerable inter- est from human architecture. Otherwise, research on termite mounds has been scattered, with little work on their explicit properties. This review is focused on how termites design and build functional structures as nest, nursery and food storage; for thermoregulation and climatisation; as defence, shelter and refuge; as a foraging tool or building material; and for colony communication, either as in indirect communication (stigmergy) or as an information channel essential for direct communication through vibrations (biotremology). Our analysis shows that systematic research is required to study the prop- erties of these structures such as porosity and material composition. High res- olution computer tomography in combination with nonlinear dynamics and methods from computational intelligence may provide breakthroughs in un- veiling the secrets of termite behaviour and their mounds. In particular, the ex- amination of dynamic and wave propagation properties of termite-built struc- tures in combination with a detailed signal analysis of termite activities is re- quired to better understand the interplay between termites and their nest as superorganism. How termite structures serve as defence in the form of disguis- ing acoustic and vibration signals from detection by predators, and what role local and global vibration synchronisation plays for building are open ques- tions that need to be addressed to provide insights into how termites utilise materials to thrive in a world of predators and competitors

Organisation of foraging in ants

In social insects, foraging is often cooperative, and so requires considerable organisation. In most ants, organisation is a bottom-up process where decisions taken by individuals result in emergent colony level patterns. Individuals base their decisions on their internal state, their past experience, and their environment. By depositing trail pheromones, for example, ants can alter the environment, and thus affect the behaviour of their nestmates. The development of emergent patterns depends on both how individuals affect the environment, and how they react to changes in the environment. Chapters 4 – 9 investigate the role of trail pheromones and route memory in the ant Lasius niger. Route memories can form rapidly and be followed accurately, and when route memories and trail pheromones contradict each other, ants overwhelmingly follow route memories (chapter 4). Route memories and trail pheromones can also interact synergistically, allowing ants to forage faster without sacrificing accuracy (chapter 5). Home range markings also interact with other information sources to affect ant behaviour (chapter 6). Trail pheromones assist experienced ants when facing complex, difficult-to-learn routes (chapter 7). When facing complicated routes, ants deposit more pheromone to assist in navigation and learning (chapter 7). Deposition of trail pheromones is suppressed by ants leaving a marked path (chapter 5), strong pheromone trails (chapter 7) and trail crowding (chapter 8). Colony level ‘decisions’ can be driven by factors other than trail pheromones, such as overcrowding at a food source (chapter 9). Chapter 10 reviews the many roles of trail pheromones in ants. Chapters 11 – 14 focus on the organisation of cooperative food retrieval. Pheidole oxyops workers arrange themselves non-randomly around items to increase transport speeds (chapter 11). Groups of ants will rotate food items to reduce drag (chapter 12). Chapters 13 and 14 encompass the ecology of cooperative transport, and how it has shaped trail pheromone recruitment in P. oxyops and Paratrechina longicornis. Lastly, chapter 15 provide a comprehensive review of cooperative transport in ants and elsewhere

Architecture, Space and Information in Constructions Built by Humans and Social Insects: a Conceptual Review

The similarities between the structures built by social insects and by humans have led to a convergence of interests between biologists and architects. This new, de facto interdisciplinary community of scholars needs a common terminology and theoretical framework in which to ground its work. In this conceptually oriented review paper, we review the terms “information”, “space” and “architecture” to provide definitions that span biology and architecture. A framework is proposed on which interdisciplinary exchange may be better served, with the view that this will aid better cross fertilisation between disciplines, working in the areas of collective behaviour and analysis of the structures and edifices constructed by non-humans; and to facilitate how this area of study may better contribute to the field of architecture. We then use these definitions to discuss the informational content of constructions built by organisms and the influence these have on behaviour, and vice versa. We review how spatial constraints inform and influence interaction between an organism and its environment, and examine the reciprocity of space and information on construction and the behaviour of humans and social insects

Could fungal infection make ant societies more open?

Ant colonies are a highly rewarding target for many pathogens and parasites and they also host various species of social parasites that exploit their social system. Myrmica ants seem to be particularly susceptible to exploitation by social parasites and by ecto- and endoparasites. Also many Myrmica colonies frequently adopt unrelated gynes, which can be interpreted as temporary social parasites. Myrmica scabrinodis is a common host of the ectoparasitic fungus Rickia wasmannii and its colonies are used by socially parasitic butterfly larvae of Maculinea genus. In some M. scabrinodis populations both R. wasmannii and Maculinea butterflies occur together using the same host colonies. In our study we used such population to check whether fungal infection change the threshold of acceptance of social parasites and unrelated queens by ants and make colonies more open for strangers. For this purpose we performed experiments during which we tested how infection by R. wasmannii affects frequency and time of Maculinea larva adoption and adoption of unrelated ant queens. We also carried out aggression tests where we used M. scabrinodis workers originating from infected and uninfected colonies to check if fungal infection influences the amount of adverse reactions. Our preliminary results indicate that ants infected by the fungus are more readily adopting social parasites, while being less aggressive towards foreign queens. Thus, infected colonies could be more prone for social parasitism

Modèle comportemental de la dynamique de construction de la structure épigée du nid chez la fourmi Lasius niger : approches expérimentales et théoriques

La structure épigée du nid de la fourmi Lasius niger, prise comme un exemple typique des structures alvéolaires construites par les insectes sociaux, résulte de l'accumulation d'actes individuels de prise, de transport et de dépôt de matériau. Nous montrons expérimentalement que ces structures émergent d'une coordination indirecte des actes de prise/dépôt par l'activité précédente : les dépôts sont plus fréquents dans les zones de forte densité, et les prises dans les zones de faible densité. Il s'agit donc d'une dynamique auto-organisée où des boucles de rétroaction amplifient des premiers dépôts aléatoires. Au cours du temps, la surface de la structure devient alvéolaire, et le déplacement des fourmis peut être affecté par ses déclivités et ses courbures. A ce stade, le processus de construction présente donc un double couplage de la structure avec d'une part les décisions comportementales de prise et de dépôt, et d'autre part le déplacement des fourmis. Pour ce dernier, nous proposons le modèle du Marcheur de Boltzmann généralisé qui intègre ces effets d'orientation par la structure. Nous proposons enfin une formulation intégrale des échanges de matériau entre points du système, qui intègre tous ces éléments. Ce formalisme confirme le critère d'émergence obtenu par l'analyse linéaire de stabilité classique sur la phase initiale et permet de comprendre les mécanismes essentiels de cette dynamique, en lien direct avec la représentation du phénomène en termes de comportements individuels.Epigenous part of the nest in the ant Lasius niger is a typical example of sponge-like structures built by social insects. It results from accumulated tiny pellets of material which are picked up, moved and dropped by individuals. We show experimentally that these structured patterns emerge from a coordination of individual decisions mediated by the evolving density of material: they pick up more often in depleted zones and drop preferentially in high-density zones. This self-organized process allows random fluctuations in early material density field to be amplified through time. The building then evolves towards a sponge-like structure, so that the surface displays slopes and curvatures, which might in turn affect motion decisions. In late stage, the coupling between density and behavioral decisions is then intricated with coupling between geometry and motion. For the latter, we designed the Generalized Boltzmann Walker model so as to integrate local geometry with random walk. We demonstrate experimentally its relevance for the effect of slopes. Eventually, we analyze the whole process within an analysis of net exchange of material between pairs of locations. We confirm then some results obtained by classical linear stability analysis, and explain essential properties of those dynamics in terms of measured individual behaviors and cognitive properties

Etude expérimentale et modélisation des processus de morphogenèse de structures complexes chez les insectes sociaux

La construction d'un nid est un comportement que l'on rencontre dans tout le règne animal. Ce nid aura en particulier le rôle de protéger l'animal, sa progéniture et la nourriture, des conditions extérieures et des éventuels prédateurs. Les nids les plus spectaculaires résultant d'activités collectives. Dans un premier temps, nous nous sommes intéressés à l'effet d'une variation environnementale, la rugosité du substrat, sur les structures résultant de l'activité de construction chez la fourmi Lasius niger, notamment des piliers dont nous avons observé la dynamique spatio-temporelle grâce a un scanneur de surface. Nous n'avons trouvé aucun effet de la rugosité sur les variables étudiées (vitesse de construction, distances inter-pilier). Dans un second temps, nous nous sommes intéressés au phénomène de déplacement chez la fourmi Lasius niger. Nous avons construit un modèle de pistes avec angle de perception et un autre modèle avec diffusion de phéromones. Une analyse de sensibilité a montré que la vitesse d'apparition de pistes est fortement influencé par le taux de dépôt et d'évaporation de phéromones, moins fortement par l'angle de perception et qu'elle est quasiment indépendante de la diffusion de phéromones. Enfin, nos recherches ont porté sur le phénomène thigmotactique chez la fourmi Lasius niger. On a d'abord confirmé que les fourmis Lasius niger ne déposent pas de phéromones pendant la phase exploratoire. Pour comprendre la distribution spatiale durant l'exploration, nous analysons les comportements thigmotactiques de Lasius niger et identifions les règles comportementales pendant le déplacement et les arrêts des fourmis. On a construit une hiérarchie de modèles individus-centrés de mouvements individuels pour vérifier si ces règles comportementales peuvent expliquer la distribution spatiale des fourmis. On a trouvé une bonne cohérence qualitative, mais une nouvelle méthode de sélection de modèle indique que tous nos modèles sont quantitativement différents des observations.Nests and the related construction behaviors can be found throughout the animal kingdom. Nests should protect the animal, its descendants and its food from environmental conditions and predators. The most spectacular nests can be found in social animals where they result from collective activities. In the first chapter we ask whether an environmental variable (roughness of the surface) influences the structures built by the black garden ant Lasius niger, in particular pillar formation. The spatiotemporal dynamics of this activity had been observed in the laboratory with a surface scanner. We did not find any significant effect of surface roughness on the studied variables (construction speed, inter-pillar distances). In the second chapter we focus on the movement of Lasius niger during exploration. We built a model with a perception angle and another model with diffusion of the pheromone traces. A sensitivity analysis showed that trail appearance speed is strongly influenced by pheromone deposition or evaporation rates, less strongly by the perception angle and that seems to be independent of pheromone diffusion. Finally, our research focused on the thigmotactic behavior in the ant Lasius Niger and the resulting ant densities in an experimental setup with borders. We at first confirmed that Lasius Niger ants do not lay pheromone trails during the exploration phase. In order to understand their spatial distribution during exploration , we analyzed their thigmotactic behavior and identified the behavioral rules underlying movement and stopping. We built a hierarchy of individual based models to test if the identified behavioral rules can explain the ants' spatial distribution. We find a good qualitative coherence, but a new model selection method shows that all our models differ quantitatively from the observations