Science series. The team looks at the science of crowds, discovering how architects control the flow of crowds and how people in them can co-operate subconsciously.
Dallas finds out how crowds can co-operate subconsciously, Liz sees how architects control the flow of crowds, and Jem meets scientists trying to understand how crush injuries can occur. Plus, 80s number cruncher, Johnny Ball, demonstrates just how biologists measure population size.
The programme is produced in partnership with the Open University.