Pre-Industrial Energy!

Summary:
Chapter four of the book 'Energies' by Vaclav Smil shows how societies progressed from being pre-industrial to what they are today. Originally, all humans were hunters and gatherers. Over the course of time, people became more advanced and adopted better methods of gathering food, allowing people to focus their attention towards other matters than survival of the fittest. Farmers adopted cattle to plow their fields, and eventually, machines. Each adopted method of energy gathering that was adopted by civilizations led to increased productivity output. There is also a small section of the chapter dedicated to comparing coal and wood.

Comments:
~The ultimate source of energy in a pre-industrial society is the sun!
~An example of a pre-industrial innovation is the waterwheel. The waterwheel had a dramatic effect on human productions.
~One of the major setbacks to pre-industrial societies was that not everyone could have energy. You could only have energy if you lived nearby a windmill or a waterwheel. Without a local river, or a lot of wind, you could not have energy.
~The heat source of home when my family and I first moved in was a coal oven!(which was replaced by a wood stove)

Questions:
~How long did it take humans to realize animals were a good form of labor?
~If coal was known to be wasteful, than why did people use it? Why do people still use it today?
~I am curious about what old windmills used to be like, and how they are different from modern windmills.