Model Library
Evidence So Far tracks how confident the site is in each result. This page is the complementary map: every simulation model on the site, organized by family, with what each one tests and a link to go read it. Use it to find a specific model rather than to judge how conclusive it is.
How to Read This Page
Each table has an Adaptation column that says what kind of process the model runs:
- Evolution — selection on an inherited trait or strategy across generations, with no within-lifetime learning.
- Learning — within-lifetime adaptation only, with no evolutionary component.
- Evolution + Learning — both act together, which is the site's central two-timescale claim.
Nowak Mechanisms
Five thin wrappers over a shared Moran-process engine, one per classical mechanism for the evolution of cooperation identified in Nowak (2006).
| Model | Adaptation | What it demonstrates | Explore |
|---|---|---|---|
| Kin Selection | Evolution | Cooperation spreads when benefit routed to relatives, weighted by relatedness, exceeds its private cost — Hamilton's rule rB > C. | Kin Selection |
| Direct Reciprocity | Evolution | Cooperation sustained by repeated encounters: a cooperator can reward or punish the same partner next round, but only if they meet again. | Direct Reciprocity |
| Indirect Reciprocity | Evolution | Cooperation sustained by reputation: agents help others whose public reputation signals they are good cooperators, without needing repeated encounters. | Indirect Reciprocity |
| Network Reciprocity | Evolution | Cooperation sustained by spatial structure: local-neighborhood interaction lets cooperator clusters form and shield each other from exploitation. | Network Reciprocity |
| Group Selection | Evolution | A second level of selection on top of individual competition: the most successful group is periodically copied into the least successful group. | Group Selection |
Ecological Models
Four case studies that embed a cooperation problem inside a spatial, ecological setting rather than an abstract Moran process.
| Model | Adaptation | What it demonstrates | Explore |
|---|---|---|---|
| Spatial Altruism | Evolution | The minimal case study: whether an altruistic inherited type can survive local exploitation once reproduction is local and empty space is a competitor. | Spatial Altruism |
| Cooperative Hunting | Evolution | Whether an inherited, continuously-valued hunt-investment trait can spread when it costs the individual predator but pays off only through successful shared hunts. | Cooperative Hunting |
| Spatial Prisoner's Dilemma | Evolution | What inherited response rules spread when agents repeatedly play a local Prisoner's Dilemma and reproduce into nearby empty cells using accumulated energy. | Spatial Prisoner's Dilemma |
| Retained Benefit | Evolution | The most abstract case study: strips away mechanism-specific structure to ask how much of the value cooperation creates has to be routed back to cooperators for it to spread. | Retained Benefit |
Learning × Selection Interaction Models
The models that test the site's central claim directly: that within-lifetime learning and between-generation selection can work better together than either alone.
| Model | Adaptation | What it demonstrates | Explore |
|---|---|---|---|
| PredPreyGrass | Evolution + Learning | A richer predator-prey-grass ecology used to test whether the genome needs a direct channel into individual behavior for selection-driven behavioral evolution to become visible. | PredPreyGrass |
| Model 1: Trust Learning | Evolution + Learning | Baseline two-timescale model: agents learn a scalar trust value per partner within a lifetime, and evolution selects the inherited parameters that shape that learning. | Model 1 |
| Model 2: Q-learning | Evolution + Learning | Same two-timescale framework as Model 1, but with action-value (Q-learning) reinforcement learning replacing scalar trust. | Model 2 |
| Model 3: Extended | Evolution + Learning | Adds reputation, partner choice, and forgiveness on top of Q-learning, shifting the outcome toward conditional cooperation with active monitoring. | Model 3 |
| Network Diversity Experiment | Evolution + Learning | Not a new model — runs Models 1 through 3 under systematically varied network conditions to test when partner-memory alone stops being enough. | Network Diversity |
Learned Cooperation Models
The Prisoner's Dilemma and Repeated Prisoner's Dilemma pages set up the game-theoretic background; the PPO Study is the model that actually runs it.
| Model | Adaptation | What it demonstrates | Explore |
|---|---|---|---|
| PPO Study | Learning | Two independently trained PPO agents repeatedly play a Prisoner's Dilemma, testing whether learned behavior converges to persistent defection, cooperative conventions, or mixed horizon-dependent patterns. | PPO Study |
Foundational Replications
From-scratch replications of the papers that established the two-timescale claim this site builds on.
| Model | Adaptation | What it demonstrates | Explore |
|---|---|---|---|
| Ackley & Littman (1991) | Evolution + Learning | A neural-network-controlled creature that senses, moves, eats, fights, and reproduces, testing whether combining an evolving genome with within-lifetime reinforcement learning beats either alone. This site's strongest confirmed result. | Ackley & Littman (1991) |
| Hinton & Nowlan (1987) | Evolution + Learning | The needle-in-a-haystack landscape that gave the Baldwin effect its modern computational footing: whether within-lifetime learning can manufacture a gradient where genetic search alone has none. Includes an interactive demo. | Hinton & Nowlan (1987) |
| Prosser (2022) | Evolution + Learning | Tests what changes when learning acts on genetically correlated groups of traits, with the correlation structure itself evolving, instead of on independent single loci. | Prosser (2022) |