Names the loop culture compounds through: innovate, transmit, improve, repeat.
The term was being used for very different things, so the paper writes down criteria. A change in behavior. Transmitted socially. Producing a measurable improvement in performance. Repeated, so improvements stack on earlier improvements.
They then add stricter criteria, including traits no single individual could have invented alone, and apply the whole set to the animal and human cases people had claimed.
Most animal cases satisfy the core criteria and fail the strict ones. The value here is the definition, not the verdict: it turns a word people were arguing about into something you can test a system against.