One way of measuring intelligence is to look at what decisions an animal has to take in order to find food, to protect itself, and to live with others in a group.
Predators that stalk their prey take more decisions than animals that simply find food lying around.
Animals that are both predators and prey have more to think about than animals that are one or the other.
Animals that live in groups take complicated decisions. They have to adapt their activities to others and are smarter than animals that live alone.
