A basic human need covered in the video was shleter, and how the evolution of buliding it has changed.  Cranes were specifically covered in th video.  A Mideveil crane, called a treadmill crane was powered with men walking in a giant wheel.


Today, a crane is much more advanced, and not powered by walking.  Instead they are powered by gasoline, with someone running the gears. 

Cranes are an essential part of buliding shelter.  In midevil times they were used to create cathedrals, such as the one pictured below.  Although there have been many advances in crane technology, they still serve the same purpose of raising large pieces of the building.