Background

From making pins...

While the benefits of division of labour in a system were recognised as far back as 380BC (Plato’s The Republic), the one to properly introduce the term and analyse its implications on economics was Adam Smith (1776) in his pivotal work ‘The Wealth of Nations’. Indeed he opens with the sentence:

“The greatest improvement in the productive powers of labour, and the greater part of the skill, dexterity and judgement with which it is anywhere directed or applied, seem to have been the effects of the division of labour.”

In order to illustrate the meaning of Division of Labour, Smith uses the trivial example of the pin-making trade. The process of making a single pin can be subdivided to about 15 distinct operations. For one man to carry out all of these in turn will take a long time indeed; however, with 10 men, each of whom performs only one or two of the steps, the productivity will be considerably higher. The efficiency of the trade is much increased by the division of operations. This simple idea has contributed greatly to the development of manufacturing, technology and economics of the modern world, as the same principle applies to such ingenious inventions as production and assembly lines.

...to navigating ships...

Building up on these concepts, it can also be argued that not only physical labour, but also knowledge and cognitive processes can be divided up among multiple components of a system. Edwin Hutchins (1995) even takes this one step further and argues that cognition can indeed be divided up among individuals but also resides in so-called ‘artifacts’ or ‘tools’. He coined this principle “Distributed Cognition”. Hence, cognition is thought to be both distributed among internal resources like memory and physical execution (by humans) and among external resources like objects and materials (the ‘tools’).

One very elegant example, described by Edwin Hutchins, is the distributed cognition necessary for the navigation of a ship. Hutchins explains that in order for the captain to safely navigate the ship into a port he needs multiple inputs from different components of a complex system, which includes humans and tools. First of all, two sailors at each side of the ship use telescopes to record angular locations of landmarks relative to the ship’s location. These measurements are then communicated to the pilothouse, where the navigator combines both readings to map the exact location of the ship on a chart. Only the navigator knows the outcome, by pooling the different data. He could not have achieved this neither without the other individuals in the system nor without tools like the telescopes, the telephone or the chart.

...to designing bacterial systems?

Division of labour does also have biological relevance. For example, Cyanobacteria divide up biological tasks among themselves, because they have to separate chemically incompatible processes like nitrogen fixation and photosynthesis. They evolved two different strategies to solve this problem. Some strains evolved spatial differentiation, with the two processes carried out in different locations (division of labour in space), whereas other strains are switching from photosynthesis to nitrogen production in circadian rhythms (temporal division of labour). Interestingly, Rossetti and Bagheri (2012) used mathematical modelling to compare the efficiency of those two primitive forms of division of labour. They used biomass production and population size as indicators of the strains’ overall fitness and incorporated the resource investment of the cell for reproduction and nitrogen fixation as inputs. They realised that populations with spatial division of labour invest more carbon into nitrogen fixation, and might thus be faster growing initially, but in the long term, they can be outcompeted by the circadian strains as those invest less. This study shows that it is indeed useful to think about division of labour in bacterial systems and that two different designs can have different advantages for a population.

It might be a little difficult to understand why these principles are relevant for our project and in the context of bacterial systems. Cognition is often associated with brain activity or the possession of a central nervous system, both of which bacteria obviously lack. However, here we apply ‘cognition’ as a general concept, using it as a metaphor for computation principles. Such principles encompass, for example, action and perception, decision making or learning and memory. Even though all those terms were traditionally associated with human cognition, they can also be seen to some extent in lower organisms like bacteria. All bacteria need to engage in information processing operations in order to survive. For our project in particular, we are splitting up this information processing (i.e. the splitting up of the logic gates), hence we can argue that we alter the population’s cognition or their division of processing labour. As with all things we have to think about the implications of altering said processing in a system and make sure we alter it in a strategic way. This is why we investigate other systems first, in order to make rational decisions when designing the alterations of our bacterial system.