The longevity of oral history

One reason unbelievers claim Biblical accounts are unreliable is because they were (allegedly) written so long after the fact. For instance, Bart Ehrman recently published a book on the subject. Yet there are two preliminary problems with this claim:

i) It presumes a late date for the documents or the underlying sources.

ii) It disregards the possibility of revelation and inspiration.

That said, the claim suffers from another problem. For there's evidence that under the right conditions, oral history can be reliable across centuries or even millennia. For instance:

One time when the Chief of the Below World was on the earth he saw Loha, the daughter of the tribal chief. Loha was a beautiful maiden, tall and straight as the arrowwood. The Chief of the Below World saw her and fell in love with her. He told her of his love and asked her to return with him to his lodge inside the mountain. But Loha refused to go with him. The Chief of the Below World was very angry. He swore he would have revenge on the people of Loha, that he would destroy them with the Curse of Fire. Raging and thundering on the top of his mountain, he saw the face of the Chief of the Above World on the top of Mount Shasta. From their mountaintops the two spirit chiefs began a furious battle. Mountains shook and crumbled. Red-hot rocks as large as the hills hurtled through the skies. Burning ashes fell like rain. The Chief of the Below World spewed fire from his mouth. Like an ocean of flame it devoured the forests on the mountains and the valleys. The Curse of Fire reached the homes of the people. Fleeing in terror before it, they found refuge in Klamath Lake. This time the Chief Below the World was driven into his home, and the mountain fell upon him. When the morning sun rose, the high mountain was gone. The mountain which the Chief Below the World had called his own no longer towered near Mount Shasta. For many years the rain fell in torrents and filled the great hole that was made when the mountain fell upon the Chief of the Below World. Now you understand why my people do not visit the lake. From father to son has come the warning “Do not look upon this place.” – Klamath story, recorded 1865 [Clark 1953, 53-55]

Who can doubt that we have here a vocalic eruption, with its river of fire, quakes, ash-fall, and lava bombs? Certainly no one who has followed the recent eruptions of Etna, Pinatubo, and Shasta's neighbor Mt. St. Helens.  

Is transmission of oral information across centuries even possible? We read in the newspaper about how unreliable the witnesses to accidents and crimes can be a month later. What hope is there that verbal information could survive so long intact?  

The Klamath story quoted above refers specifically to the place we know as Crater Lake–in fact, the story was related as answer to a young soldier at Fort Klamath when he inquired why the native people never went to that breathtakingly beautiful spot.  

After emptying its magma chamber of lava in a catastrophic eruption, [Mt.] Mazama collapsed to form a crater 4,000 feet deep which, as the narrative relates, never erupted violently again and gradually filled with water to form today's magnificent Crater Lake. That eruption, so accurately described and vehemently warned against in the tale, has been ice-dated to 7,675 years ago. So, yes, real information can reach us intact across more than seven millennia of retelling. Even if we might not agree with their explanation of why these things occurred, the Klamath tribe in the 1860s still knew in considerable detail of events observed millennia earlier.  

Vine Deloria Jr. came to the same conclusion about the Klamath myth of Crater Lake in his book Red Earth, White Lives [1995, 194-98]. We find Deloria also interprets much the way we do the Bridge of the Gods (the Dalles), the disappearance of Spokane Lake, and various other Pacific Northwest myths–all as recording specific geologically reconstructible events. And he too has collected massive evidence for the extreme longevity of these myths. Both we and Deloria are also indebted to Dorothy Vitaliano's book Legends of the Earth [1973], which appeared not long before we began collecting our Myth Principles. 

Evidence abounds from several continents, in fact, that properly encoded information has passed unscathed through the oral pipeline for one to ten thousand years and more–for example, in Australia [Dixon 1984, 153-55,295]. But the conditions must be right for this to happen. 

First of all, the information must be viewed as important, as in the Klamath warning about innocent-looking Crater Lake. 

Second, the information must continue to correspond to something still visible to the hearers, such as Crater Lake to the Klamath. If tellers of volcano myths migrate away from all volcanos, the original meaning of those myths is sure to become clouded or lost. 

The third condition for intact transmission is that it be encoded in a highly memorable way…An unbroken chain of good memories is part of the condition. But that chain is more likely to stay intact if the information is embedded vividly (so as to be more memorable) or encoded into the story multiple times (so there is a back-up)…The latter strategy is called redundancy. E. Barber & P. Barber, When They Severed Earth from Sky: How the Human Mind Shapes Myth (Princeton University Press, 2006), 6-10.

Consider how many Biblical narratives meet these conditions. Biblical narratives often record intrinsically memorable events. 

Bible writers often live in the vicinity of the reported events, where natural landmarks are visible. In addition, God sometimes commands the Israelites to construct memorials. 

Moreover, the event is often encoded in ritual. Religious ritual can function as a mnemonic device, where perennial repetition of the rite prompts collective memory of the event it commemorates (e.g. Passover; Eucharist). Furthermore, the event is often recorded in dramatic imagery. Finally, the event is often recorded in multiple sources.