Professor Fekri Hassan attempts to determine why the Egyptian Old Kingdom, the civilisation of the great pyramids, collapsed around 2200 BC. Can science show that terrible forces of nature were to blame - even driving people to cannibalism? Clues come from the remote deserts of southern Egypt, the glaciers of Iceland and a dramatic and unique archaeological find in the Nile delta.

In the ninth century AD, the great Maya civilisation in Central America and southern Mexico all but disappeared. Millions died and great cities were abandoned to the jungle. Why this happened was a mystery, until science started unlocking the secrets of the past to reveal the brutality of nature.