Learn more about the science in
The Serengeti Rules

Below are a number of educational resources developed by Howard Hughes Medical Institute’s science education group BioInteractive, which develops in classroom life science materials aligned to national standards for high school and undergraduate students.



The Serengeti rules are rules of logic that govern how ecosystems and other biological systems work, many of which have been studied in the Serengeti ecosystem. They help explain how organisms interact with one another and what controls population sizes.

Scene from   The Serengeti Rules

Scene from The Serengeti Rules


What is an ECOSYSTEM?

An ecosystem is a community of living organisms such as plants, animals and microbes interacting with one another and their non-living environment in a particular area.



A trophic cascade is a phenomenon where species impact other species even if there are no direct interactions among them.

For example, Dr. Jim Estes showed that sea otters control the population of sea urchins, which eat kelp. Thus, the otter indirectly affect the amount of kelp and impact all the species that depend on kelp.

Learn more about trophic cascades through the following resources:



A keystone species is a species that has an outsized influence on an ecosystem and if it were removed the ecosystem would change drastically.

Dr. Robert Paine’s discovery of the effects of starfish in tidal pools changed the way ecologists thought about ecosystems.

You can learn more about keystones species and Dr. Paine’s experiments here:

A young  Bob Paine  as seen in   The Serengeti Rules

A young Bob Paine as seen in The Serengeti Rules


What is Downgrading?

Downgrading is a term used when ecosystems are disrupted because of the elimination of species at the top of a food web, which in many cases are predators.


What is Upgrading?

Upgrading refers to the recovery of an ecosystem through the re-introduction of a species at the top of a food web and leads to a restoration of the system.