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The Small-Brained Path to Building Successby Mike Hansell
This audience response took me quite by surprise because I had not actually thought of my message as a joke, but rather as the most fundamentally important message that I wanted to convey. To illustrate it I give you this structure: It is a sphere composed of a few hundred stones cemented together, on top of which there are seven or eight sturdy spikes, each a cairn of stones, larger ones at the base, smallest at the tip creating a sharp point. At the bottom of the sphere there is a large circular hole ornamented with a pleated collar of particles too small to be distinguishable from the cement that binds them. The diameter of the whole dwelling, for that is what it is, is about 150 thousandths of a millimetre. Smaller than the punctuation mark at the end of this sentence. It is the portable home of Difflugia coronata, a species of amoeba.
An amoeba, as you very likely know, is a single celled organism. The one cell does everything. It feeds, excretes, moves and reproduces and, in this species, it also builds a home. The cell has no nervous system at all, let alone a brain. Can its extraordinary achievement really be said to be building? Well, as the organism's amorphous bulk glides gently round the bottom of some pond, engulfing food particles and growing, it also picks up tiny sand grains that accumulate as a mass inside it. When it grows to a certain size, the cell then reproduces by dividing its body equally into two. One of these inherits the ancestral home; the other is left the bundle of building material. These stones, we know not how, are then moved to the body surface and arranged to create the distinctive architecture of this species. Just enough particles of the right sizes, big and small, have been picked up to accomplish this.
Can what this amoeba achieves be compared with a house of bricks, beams and tiles built by me? Well, yes and no, but the most important message from any comparison is this: If I built so much as a garden shed, I would consider myself both dexterous and smart, but lots of creatures with very small brains, bees and spiders for example, make structures exhibiting elegant design and structural sophistication. Why should I feel so proud of my creative efforts? The conclusion must be that non-human builders use techniques that keep behaviour simple and therefore allow the brain of a builder to be small, techniques such as minimising manipulative skill, intelligence and learning.
In my book Built by Animals the theme of small-brained builders repeatedly resurfaces. We have big brains so, when it comes to building, there is little restriction on us doing things in a big-brained way. However, we should remain aware of the fact that there may be very effective small-brained ways of achieving a similar end.
After successfully grabbing the attention of my audience of building services engineers, I went on to explain to them how some mound-building termite species, include within their massive dwelling a huge ventilation system that brings fresh air to the heart of the living quarters, expels stale air and regulates temperature and humidity levels . Not only that, but they have evolved two quite different ways of powering the air circulation, both using renewable energy sources. One system is powered by temperature differences, largely due to daytime heating of the exterior wall of the mound by the sun, the other system powered by air pressure differences created as wind passes over the surface of the mound. How do termites manage to build a ventilation system, let alone integrate it with the other architectural elements: royal apartments, nursery chambers, fungus cultivation chambers, all within a protective outer wall? Well, I barely know the rules of chess and it is decades since I last played, but I still feel confident that I could beat a termite. There has to be a small-brained way to build a collective home nearly seven metres (23 feet) high.
There is another complication that the termites face and which I don't in building my shed. theirs is a collective effort. I say complication because to undertake such a massive civil engineering project as building a termite mound requires an insect workforce of tens or possibly hundreds of thousands. If it were an equivalent human project, we would need a team of architects and design engineers (not forgetting those for building services). They would then contract the building work to a variety of specialist construction companies, who would employ and assortment of craftsmen, tradesmen, and labourers. They would all be integrated into a hierarchical system with elaborate communication between and across levels particularly, from the top down.
But termites are small brained. They can't cope with all that. What, then, is the small-brained way to organise a large workforce to build a giant skyscraper? We are still quite vague about the detail, but are beginning to get a good appreciation of the general nature of their system. So, first of all, who is the termite architect? Well no-one or, if you like, everyone. All seem to know what to do. There is no foreman, boss or manager telling the less elevated what to do, who in turn take it out on their inferiors. There is probably a degree of job specialisation and certainly some communication, however, what a termite converses with most is the structure itself. If a termite puts a bit of mud building material in a particular place on the wall, it can ask the wall what it looks like. The wall, through its dimensions, proportions and, as it turns out for termites, its smell, tells the termite what it is like. The termite responds by putting another blob, this time in a new place, and consults the structure again.
Does the termite understand that now it is building a royal apartment and now a ventilation shaft? Almost certainly not; it just knows what building rules currently apply. From that, structures just emerge. What's that supposed to mean 'just emerge'? Well, think how you would explain to me over the phone how to build a brick wall. You could give me a simple set of rules, an infinite supply of bricks and then say 'go'. When you returned many years later, you would discover I had built the Great Wall of China or its equivalent anyway. You would not need to even tell me to build a wall. If you simply gave me instructions that always allowed me to fit the next brick, a wall would be an emergent property of applying those rules. Is that all termites do consult simple rules? Perhaps not, but we are now at the stage of being able to show in a computer simulation that a bunch of virtual creatures, given a set of simple building rules and no communication between each other at all, create elegant, organised architecture. Our way of organising workforces to build is not the only one.
Once you accept that animal solutions are not simply like ours only less good, but more often just different, new possibilities open up which are worth exploring. To the question of how insects organise workforces, I would like to add two more, one about traps the other about tools. Do animals need brains to make these two things? In the 1960s the animal behaviour researcher Jane Goodall, in an extended study of the behaviour of chimpanzees in the wild, provided detailed evidence of the manufacture and use of tools. Chimpanzees, she observed, would strip the leaves from a grassy stem to create a fine probe that could be pushed gently into a termite mound. Large soldier termites defending the nest, grasping the intruding stem could then be gently withdrawn to provide a snack for the chimpanzee tool maker. The chimpanzees seemed to have devised a plan to capture termites lurking deep inside their mound, and invented and constructed a tool to catch them. This behaviour was greeted with excitement at the time because it seemed to show that tool making had been a landmark in the evolution of humans and our subsequent global dominance.
The use of tools has remained a topic of great research interest for those studying human evolution. But if, as seems the case, a mighty termite mound can be built by a bunch of minute-brained creatures who don't know what they are building, why does a chimpanzee need to be particularly intelligent or skillful to make and use a simple grass stem tool? If your answer is that tool making is difficult compared with nest building, then please explain to me why there is at least one kind of tool making insect and similarly a tool making spider. There must be a small brained solution.
What then of trap making? If, in the footsteps of Jane Goodall, you came across a group of chimpanzees that made nets to catch fish, you would consider your research reputation made. Not a single vertebrate animal: bird, snake, fish, or mammal (other than us humans) makes a trap of any kind. Too technically difficult? Too sophisticated a concept? So explain to me why a host of small brained creatures, invertebrate animals, including the majority of spider species uses traps to capture food. I would like to discuss these matters with you in more detail, but just remember the words on the screen: 'You don't need brains to be a builder.'
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Mike Hansell is Emeritus Professor of Animal Architecture at the University of Glasgow. Author of Animal Architecture and Bird Nests and Construction Behavior, he is a leading authority on animal building.