From Trevor Prew, Sheffield, UK
You ponder the question of when civilisation actually began. I have always viewed a key indicator of this as the advent of drainage. Disposal of human effluent and waste requires organised communities, surplus resources, management structures and a sense that sanitation is important. So, for Britain, civilisation started with the Romans, then departed, returning much later. Putting up a few stone monuments or wooden huts isn’t a civilisation (22 February, p 36).
