u/SimulatedEcology

ABM spanning the last Ice Age: glaciers advance and retreat, vegetation shifts, mammoths graze, saber-tooths hunt. Each species responds only to local conditions — temperature, food availability, prey density.

The collapse is sequential: glaciers shrink the habitable zone → vegetation disappears → mammoths starve → saber-tooths lose their prey and follow.

Full 9-minute simulation: https://youtu.be/UpbvDizaG_I

No human hunting modelled here — purely climate-driven. Curious how much the debate would shift if you added a human pressure layer on top.

Predator-prey ABM built in Python/NumPy. Each agent moves, eats, reproduces, and dies based on local conditions — no global rules.

The key mechanic is wolf vision radius: wolves can only detect sheep within a limited range. When sheep density drops, wolves start roaming blind and starving — which is what drives the collapse you see here.

Full 9-minute simulation: https://youtu.be/wqR4A4FUABs

John Calhoun's Universe 25 (1968–1973): 8 mice placed in a enclosure with unlimited food, water, and nesting space. No disease, no predators. A literal utopia.

What happened:

🔵 Normal mice reproduced normally at first

🔴 Aggressive mice emerged as density increased — disrupting social hierarchies

🟡 "Beautiful Ones" appeared — mice that completely withdrew from society, spending all day grooming, never fighting, never mating

📉 Once the Beautiful One fraction crossed ~25%, reproduction essentially stopped — even as population dropped and space opened back up

Calhoun's key finding: the collapse was behavioral, not resource-based. Mice raised during the chaos never learned normal social behaviors. Even with plenty of space and food, they couldn't recover.

This simulation models the stress-cascade and state transitions he described. Built in Python with NumPy.

Full 10-minute simulation: https://youtu.be/wXfq6jY00Lk