Story : In the second episode of Superquark a documentary from the new BBC series Human Planet: Rivers. The rivers of our planet provide many of the essentials for life: fresh water, natural routes of communication and entertainment, but living on a river can be a risk, whether it is the Amazon or the Ganges. The dangerous and incredible life of those who live "of" the river. How many times in the countryside have we seen those extraordinary webs built by spiders in the bushes, to trap insects? Today researchers have understood that spider thread could be a very precious material, for many uses, because it has a resistance that no other material we have built has. It could, for example, replace the cartilage of the knees. And this prospect is now very close to clinical application. In the report by Barbara Bernardini. In less than a century, cyclists' performances have skyrocketed: from 23 km/h in 1914 to 40 km/h in 2009.