Chemistry

There are two sources of energy in the dish: food and the atmosphere. By breathing the elements in the atmosphere, a narjillo can survive and reproduce successfully even without ever consuming food.

The atmosphere contains four chemical elements: Oxygen (O), Hydrogen (H), Nitrogen (N) and "Element X", also known as the Catalyst. The rules of breathing are complicated, but the result is simple. First, here are the rules:

• Each Narjillo can breath O, H, or N, depending on its dominant color: for example, a narjillo that is mostly red will breathe O, while a narjillo that is mostly green will breathe H.
• As it breathes, the narjillo converts that element to another element, that is determined by its genes. For example, it can convert O to N. None of these three elements is ever created or destroyed-only converted to another element. This means that the amount of O, H, and N in the atmosphere varies all the time, but their total sum is a constant.
• A narjillo can never convert an element into itself (narjillos that are born with a set of genes that convert, for example, O to O, are out of luck, and cannot breathe at all).
• As it breathes, the narjillo gains energy. The amount of energy it gains is proportional to the density of its breathed element in the atmosphere. For example, if the atmosphere is mostly N, then a narjillo that breathes N can live and prosper on breathing alone, even without ever eating food. On the other hand, if the atmosphere is mostly O and H, then a narjillo that breathes N gains little or no energy from breathing.
• The Catalyst (X) has a special role: X is never converted, and nothing is ever converted to X. All narjillos consume X during their breathing cycle to extract energy from the conversion of O, N or H. If there is no X available, then narjillos cannot gain energy while breathing. Luckily, there is a constant amount of X in the atmosphere, that is continuously refilled. This fixed amount of X is divided across all narjillos in the dish at every tick. This means that if there are just a few narjillos, they will get a lot of X, and they will breathe very efficiently. As the number of narjillos rises, the amount of X available for each individual drops, and all creatures become less efficient at breathing.

Complicated rules, as I told you-but the outcome is simple: Narjillos help each other breathe in a closed-cycle ecosystem. It works like this: imagine that a species of narjillos evolves, that converts O to N. This species will quickly exhaust all the O in the atmosphere, and become unable to breathe. On the other hand, if the dish contains a second species that converts N to O, then the two species can reach a stable equilibrium, where they both can prosper. Each species will consume its own favourite element, and convert it to the element that the other species needs to survive. On the other hand, all individuals of both species need X to breathe, and X is a fixed, limited resource. This means that the two species cannot reproduce indefinitely: too many individuals would consume all the available X, and become unable to breathe. The result is a balanced ecosystem where no species can easily take over the dish, or overpopulate it, without ultimately causing its own decline, and sometimes its own extinction.

Breathing is not strictly necessary. A narjillo could survive and reproduce successfully without breathing, as long as it gets a lot of energy from food. But reaching food requires movement, that consumes energy. So a narjillo has to evolve its own way of gaining energy, which usually involves either moving a lot to reach food, or standing very still to spare energy, and get energy from the atmosphere-or any combination of the two.