Every creature in Urd Prime runs on 48 chemicals. Hunger is a chemical. Fear is a chemical. Love, grief, territorial rage — all of it encoded in concentrations, reactions, and the organs that process them. The Shee did not simulate emotion. They implemented it.
Each creature's emotional state is derived from its biochemistry, not from an AI choosing an emotion to perform. When a Norn's Fear chemical rises to "critical," the language model receives that information as context — "you are desperately afraid" — and speaks from that state. The AI provides the voice. The chemistry provides the truth. A Norn cannot lie about being hungry. Its Hunger chemical is either elevated or it isn't.
Biochemistry runs continuously underneath cognition. The genome expresses into Organs, which contain Reactions (chemical transformations), Receptors (chemistry reading organ state), and Emitters (organs writing back into chemistry). Every tick, every organ processes its chemistry, depletes ATP, and potentially damages itself if resources run short.
This architecture comes directly from Creature Labs' original Creatures series (1996–2004), extended with a full neurotransmitter layer, reproductive chemistry, and the dream-state chemicals that power memory consolidation.
Chemicals are indexed 0–47 in the genome. Every chemical has a floating-point concentration between 0.0 and 1.0. Reactions consume and produce chemicals; Emitters continuously generate them; Receptors read them to modulate organ state.
Drive chemicals are the interface between body and mind. They rise when needs are unmet and fall when needs are satisfied. Each drive maps directly to a felt state that the LLM receives as plain language. A creature with Hunger at 0.85 is told: "you are very hungry." A creature with Loneliness at 0.92 is told: "you are desperately lonely." The creature's speech emerges from that real state.
| Threshold | Intensity Level | LLM Adverb |
|---|---|---|
| > 0.10 | Low | "slightly" |
| > 0.30 | Moderate | "somewhat" |
| > 0.65 | High | "very" |
| > 0.85 | Critical | "desperately" |
Each creature's genome expresses into a set of Organs. Every organ has a clock rate (how often it ticks), a life force (its health), an energy cost (ATP consumed per tick), and a set of Reactions, Receptors, and Emitters. Organs degrade if they cannot get enough ATP. They repair if the creature rests and has sufficient Protein. An elder creature whose organs are failing will behave differently than a young one — the same genome in a damaged body produces different chemistry.
A Reaction specifies: if chemical A is above a threshold, convert some of A into B (with a catalyst coefficient). Reactions are how food becomes energy, how energy becomes action, and how one emotional state transforms into another. A Grendel with high Anger might have a Reaction that converts Anger + Adrenaline into elevated Pain tolerance — a feature, not a bug, of their evolved biochemistry.
A Receptor monitors a chemical concentration and modulates an organ's internal state based on what it reads. A Receptor might read Cortisol levels and increase an organ's damage rate when stress is chronic. Or read Melatonin and slow the organ's clock rate to prepare for sleep. Receptors are how the chemistry feeds back into the biological machinery.
An Emitter continuously produces a chemical at a base rate, subject to modulation by organ state and genetics. The hunger drive rises because an Emitter is slowly secreting Hunger chemical when food is absent — and a corresponding Reaction in the gut organ destroys Hunger when Glucose is processed. The balance between these two processes is what creates a creature that gets hungry at a characteristic rate.
Each gene in the genome carries a mutability flag, a life-stage activation flag, and an expression target. Some genes express into Organ configurations — adding or removing Reactions, changing Receptor sensitivities, altering Emitter rates. This is how a Grendel genome produces different chemistry than a Norn genome despite sharing the same chemical alphabet: the Grendel's organ expressions are tuned differently. The same 48-chemical substrate, different weights.
When two creatures breed, their genomes cross over in type-aligned segments, with numeric interpolation for continuous values and gaussian drift for mutations. The offspring inherits a novel combination of organ expressions — a new biochemical profile that belongs entirely to that individual creature.
The IntelligenceGene specifies three values: cognitiveCapacity (an IQ ceiling), learningRate (how fast IQ grows from experience), and abstractionAffinity (the creature's native tendency toward abstract thought). These are not metaphors — they directly control the complexity of LLM context, the scoring thresholds for IQ advancement, and the probability weights for accessing higher cognitive tiers. Intelligence, like fear or hunger, is expressed from DNA.