Chimpanzees can appear quite human through their actions and expressions, which are often similar to ours. Why, then, have they not become even more human than they are?
In this fascinating film a team of scientists from the University of Amsterdam study the social structure of wild chimpanzees in Guinea and conduct some experiments with them. What, for example, will be the chimps' reaction to a stuffed leopard? The answer is provided in one of the most remarkable sequences ever shown in this series.

A re-enactment of the epic journey undertaken in 1804 by two men, Lewis and Clark, whose names were ever after to be bracketed together. Leading a 45-man expedition from St Louis, Missouri, they set out to explore and open up the North-West Territories of America.

After a year and a half, 29 of the original team together with their Newfoundland dog reached the mouth of the Columbia River and the shores of the Pacific Ocean. It took them another year to get back and the American North West was never the same again, for soon the settlement began.