It turns out your real estate agent was right. In determining the historic reasons why societies thrived and conquered, while others stayed backward, the answer is: location, location, location.

At least that's the persuasive theory advanced by Jared Diamond, a UCLA professor, MacArthur "genius" grant winner and author of the best-selling book "Guns, Germs, and Steel." Now, Diamond's book has been adapted into a three-part television series by National Geographic that begins tonight at 10 on Maryland Public Television (Channel 22) and tomorrow at 9 p.m. on WETA (Channel 26). The shows strive for an epic feel, hopscotching the continents and bouncing from demonstrations of how to make food from a sago palm to how to wield a rapier while on horseback.

Diamond's argument is ambitious, the anthropological equivalent of the long-sought unified field theory in physics: It seeks to explain everything that matters. Essentially, he says that climate and accidents of ecology are the main reasons why the native peoples of Eurasia, particularly Europe, came to run the world, and not the equally industrious and capable people of Africa, Australia or the Americas.

When our hunter-gatherer ancestors made their first tentative steps toward farming, they were dependent on the native plants that grew in the world they happened to roam. The people of the Middle East won the real estate lottery: It was there that grains such as wheat and barley offered a happy combination of traits. They are relatively high in protein, easy to sow and productive compared with, say, the squash of Mesoamerica or the yams of West Africa.

Similarly, when humans started domesticating animals about 9,000 years ago, the people of the Middle East had the ancestors of goats and sheep at hand. They provided high-protein milk and meat, of course. And the eventual addition of horses and cattle provided the muscle power to pull plows and a transportation vehicle to cover large distances. Diamond surveyed all of the world's land animals over 100 pounds and found humans have been able to domesticate only 14 species. None of them occur naturally in Australia, North America or sub-Saharan Africa. One, the llama, is native to South America. All the rest began in Eurasia.

As societies expanded, the grains and domestic animals of the Middle East moved easily to the east and west. But they were not as well adapted to moving north and south, which is why you don't find wheat fields in the tropics.

The abundance of high-protein food and animal power allowed people to specialize. No longer did everyone in a society have to spend most of their time producing food. So we see the early emergence of professional bureaucrats, clergy, artists, accountants and, yes, soldiers -- all supported by the efficiency of the local agriculture.

These accidents of geography gave the societies of the Middle East a head start of several thousand years in the development of writing, metallurgy and transportation. Finally, the experience of living with domestic animals gave the people of Eurasia yet another advantage: They had developed some tolerance or immunity to crossover diseases such as smallpox, which had its origin in cattle.

The advantages of a 4,000-year head start in technology were dramatically illustrated by the events of November 1532, when Spanish conquistador Francisco Pizarro and 168 Spaniards defeated the 80,000 soldiers of Inca emperor Atahualpa without losing a single man. The Spaniards had too many advantages -- horses, steel swords and, not least, the ability to refer to the written account of how Cortez defeated the Aztecs, which gave them an example to follow. The Incas had no system of writing, had no animals suitable for cavalry and were still using bronze tools. It was no contest.

Unfortunately, there's also no contest between this television series and Diamond's book. Part of the problem is Diamond himself. The producers put the professor at the center of the story, and we watch him traveling the world, in a dugout canoe in New Guinea, walking along a railroad track in Zambia, paging through a book in a Spanish library. But the scenes are static and Diamond is no Carl Sagan. Even the supposed emotional climax of the series, which comes when he visits a facility for African children with malaria, has almost no punch.

The show compounds its difficulties by relying on a set of hokey techniques that call attention to themselves. Granted, the beginnings and spread of agriculture aren't the easiest things to dramatize. But there's enough time-lapse photography of clouds in this series to last a lifetime. And the historic reenactments look like animatronic versions of the dioramas that used to populate natural history museums. Indeed, those of a certain age might feel they're watching the modern equivalent of a school filmstrip: ponderous in pace, with its didacticism guaranteed to be 100 percent sugar-free.

For anyone truly interested in Diamond's ideas, there's a better piece of real estate than in front of the tube. It's a comfortable chair, with his book open in your lap.

Writer-host Jared Diamond in Papua New Guinea on the three-part National Geographic series.A Papua New Guinea man in "Guns, Germs and Steel," a National Geographic special in which writer Jared Diamond compares the progress of civilizations.