Study
Geometry for the selfish herd
Hamilton, William D.
Journal of Theoretical Biology, 1971
Modelled prey animals moving to reduce their own "domain of danger" — the area within which they are the nearest target to an arriving predator — and showed what aggregation pattern results when every individual does this.
- Studied in
- Animalia
- Sample size
- geometric model
Individuals reducing their personal risk by moving towards others produce an aggregated group as a by-product. Grouping can therefore arise from purely selfish behaviour, with no cooperative benefit and no group-level function required.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Herds and schools need not exist for mutual protection; they can be the incidental outcome of each animal trying to put another between itself and a predator.
How NatureHQ reads it
The paper that removed the need for a cooperative explanation of grouping, and a useful antidote to the assumption that animals together are animals helping each other. It is also a good example of a purely theoretical result that reframed how everybody interpreted the field data.
- A geometric model with strong simplifying assumptions about how predators arrive and select.
- It shows selfish behaviour is sufficient to produce groups, not that it explains any particular species’ grouping.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Elsevier journalsPublished in an Elsevier journal.
doi.org/10.1016/0022-5193(71)90189-5
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.