When most of the academics trained in the study of the ancient world look at pyramids on different continents, they see proof of humankind's division into distinct, separate civilizations. We see something quite the opposite: compelling evidence of the underlying unity of civilization.

At its most extreme, the orthodox viewpoint goes something like this. Civilization dates to no earlier than the middle fourth millennium B.C. It began in Mesopotamia, then spread to Egypt, and subsequently throughout the Old World. Other civilizations arose on their own - and much later - in the Americas, where they remained disconnected from Asia and Africa until Columbus piloted his three small ships across the Atlantic. The Old World and the New World each invented civilization independently.

I (Schoch) first came to understand there was something wrong with this view while investigating the origins of the Great Sphinx of Giza. As a geologist, I knew that the weathering patterns of the Giza plateau indicated that the Sphinx was carved in stages. In addition, the oldest portions went back much farther than the conventional 2500 B.C. date given the sculpture; the earliest part most likely predates 5000 B.C.

That finding raised a significant question. Even a first-draft Sphinx could only have been built by a sophisticated people, one that had achieved civilization well before the 3500 B.C. date when civilization supposedly arose. Who were these unknown people? And what happened to them?

The firestorm of academic controversy ignited by my research on the Sphinx led to our earlier book, Voices of the Rocks (Harmony, 1999). We argued that civilization arose earlier than generally believed, but much of the early history of humankind has been lost to natural catastrophes.

Yet we knew this was only the first word on the subject. We wanted to go deeper into the question of civilization's origins. The pyramids offer a path to the deep past.

As much as they symbolize the mystery and magic of ancient Egypt, pyramids are not uniquely Egyptian. Pyramids of various sorts also appear in the ancient African kingdom of Kush, along the Nile between the third and fourth cataracts; as ziggurats in ancient Mesopotamia and Sumeria (the likely source of the biblical account of the Tower of Babel); in England and Ireland, taking such forms as Silbury Hill and Newgrange; in India and throughout Southeast Asia, in the distinct style of the Buddhist stupa; at Angkor Wat in medieval Cambodia; at Indonesia's Borobudur; in ancient China; at Teotihuacán, Tenayuca, Tenochtitlán, and other sites in the Valley of Mexico; in the ancient Olmec and Mayan realms of southern Mexico, Guatemala, Honduras, Belize, and El Salvador; along the Mississippi, at Cahokia and other ceremonial centers; and in Peru's coastal region, among the people who were the ancestors of the Inca empire, and in that country's northern Andes, the Inca heartland.

How can it be that a form as distinctive and powerful as the pyramid was built in such widely separated locales? Most scholars would answer that the world's many pyramids are the product of coincidence and convergence - peoples of different cultures imitating forms in nature, such as the mountains of Mexico or the sand dunes of Egypt. But is this the final word on the subject? Is it an oversimplification? Could it be that pyramids around the globe share a common cultural heritage?

These questions are the focus of our most recent book, Voyages of the Pyramid Builders: The True Origins of the Pyramids from Lost Egypt to Ancient America (Tarcher/Putnam, 2003). In it we trace the many pyramid-building cultures back to what may be their ultimate source: Sundaland, a continent-sized stretch of land in Southeast Asia (located under the current southern reach of the South China Sea) that was inundated by rising sea levels after the end of the last ice age, a catastrophic event that may have been connected to cometary activity in the skies observed by the inhabitants of Sundaland.

As we argue in our book, pyramids are symbolically connected with comets, and the Sundalanders may well have originated the ancient pyramid tradition, then carried it with them as they fled the rising waters. Those who went northwest contributed to the cultural mélange that gave rise first to the pyramid cultures of Sumeria, Egypt, and Mesopotamia and later to those in India, Southeast Asia, and China. Sundalanders heading east may have gotten as far as Peru, where pyramids rose at Aspero at the end of the fourth millennium B.C. The American pyramid tradition died out until it was reinvigorated, from the twelfth century B.C. on, by Pacific Rim mariners, primarily Chinese. This contact contributed to the pyramid building of the Olmecs, which spread across Mesoamerica and later into the Andes.

Such ideas remain unpopular, in part because they smack of extreme "diffusionism" (a dirty word to many scholars) and undercut the Old World-New World division on which much of the academic orthodoxy is based. As Lisa Wynn points out in her doctoral dissertation on "Egyptology" (Princeton University, 2003), many researchers in this discipline instinctively reject alternative theories because they feel such thinking belittles indigenous Egyptians by suggesting that not all of their accomplishments were totally independent and original. Likewise, uncovering Old World precedents and influences for New World pyramids is said to constitute an insult to the Olmecs and the Mayans. Nonsense. The builders of Chartres' Gothic cathedral are no less geniuses because earlier architects had erected great cathedrals. The same holds true of the pyramids.

Joseph Campbell, that ever-astute student of mythology, argued that under the world's many, apparently different mythologies lay an ancient core of common archetypal story, one joining us all. Pyramids carry the same message: All humankind shares a common history, one in which civilization began in a single place and spread across the globe.