The researchers have visited the site for the past two summers. On their most recent trip they found charcoal and hazelnut shells.
They believe this indicates fire was used to encourage the growth of plants, such as hazelnuts, crab apples and raspberries, all which were eaten at the site.
The university archaeology department head, Prof Martin Bell, said the Severn Estuary was exceptional in its evidence of the plants used by Mesolithic people, thousands of years before farming began.
Story: BBC News | Photo: BBC News