"Economic growth and human development over the last several centuries has been the result of"

Fossil fuels...most of the growth from 1800-1970 was due to fossil fuels. Not sure why this is such a mystery to so many. Makes sense when you think about it from a physics POV. You use energy to move things, to make things, to travel to buy things, etc. Heck, the middle class wasn't a concept until the industrial revolution which was caused by...say it with me...fossil fuels.