Today, we learn from the late stone age. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

The term stone age is a mantle loosely thrown over a range of human history from two million years ago right up to the first dynasty of Egypt. It includes all but the last 5000 years. The stone age was the slow, sprawling gestation period of modern technology, which then uncoiled with blinding speed.

We break the stone age into three parts. The Paleolithic era was the long, almost static, age of hunting and gathering. It lasted until only 15,000 years ago. Stone-working technology began to move forward in the Mesolithic period. Mesolithic artisans used a much wider range of materials and techniques. Their most recent Paleolithic ancestors had just begun a new order of art with cave painting. Now they took art out of the caves and began carving figurines from stone and bone.

The third stage of the stone age was the Neolithic era -- literally the age of new stone. It was the fairly short agricultural stone age. It began 8000 years ago, and it ended as the copper alloy we call bronze came into use.

Neolithic artisans brought the use of stone, wood, and bone to a complexity that we still don't understand. The great pyramids were built when bronze was still very new. Those dazzling expressions of human will and energy were, in fact, almost a pure stone-age accomplishment. Yet they are the stone age functioning on the scale of the 20th century.

As we assemble archaeological pieces, we're startled by the range of techniques we see. Neolithic engineers had mastered means for drilling rock and sawing monoliths from mountainsides. They'd magnified human and animal force with virtuoso use of levers and pulleys.

Instrumentation is an easily overlooked part of Neolithic engineering. We find every variation of the balance, the plumb bob, and the square. The high level of late-stone-age planning and technique is evident in Stonehenge, in the fertile crescent -- even in the Ahu statues of latter-day Easter Island. Those accomplishments remind us that the inventive mind will go as far as it can, with the means at hand, and then start over.

The early Bronze age gave nothing as grand as the pyramids. Metal-working meant another new start. When the Dorians replaced bronze with iron in 1000 BC, they created a new dark age.

And so history humbles us. It limits our inflated ideas about human progress. The Neolithic engineers remind us how the human spirit will fill the room to its boundaries in every age.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Strandh, S., The History of the Machine. (American edition) New York: Dorset Press, 1989.