MENTAL MODEL · M2403

Foster's Rule / Island Rule

TechnicalHigh supportEvolutionary Biology

Included

Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

When species are isolated on islands, large animals become smaller (island dwarfism, e.g., Homo floresiensis), and small animals become larger (island gigantism, e.g., Komodo dragon). This is an adaptation to limited resources or lack of predators.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

- Resource constraints: If you start a business in a closed small market (island), do not copy the giant model of the mainland market. You need to evolve a 'dwarfed' low-energy model or a 'gigantic' monopoly model.

anchor

Anchor fast decisions

Island isolation removes species from original competition and predation pressures, and body size rebalances according to resources and predators—large species become dwarfed due to limited resources, while small species become gigantic due to lack of predators and relatively abundant resources. Environmental constraints reshape the optimal body size.

MINIMUM ACTION

In progress 0/1

Practice this model in one real situation:

First, identify your 'island' (closed small market or niche). Second, determine whether the constraint is resource scarcity or lack of competition. Third, correspondingly 'dwarf' (low-energy streamlined model) or 'gigantize' (monopolistic filling of the niche). Fourth, continuously adjust the body size strategy as the environment changes.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

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zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E7%A6%8F%E6%96%AF%E7%89%B9%E6%B3%95%E5%88%99ZH · Explicit
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