One of the reasons that we should study history is to explode the myths that so many of us have. We tend to think of myths as something believed by less educated and enlightened people, especially if they lived long ago. But I have found that although we do have better scientific and historical knowledge than people in earlier times had, we seem to acquire new myths - especially regarding the past.
I would say that the most persistent historical myth (actually found in many science textbooks) is the idea that people in Europe in the Middle Ages thought the world was flat and that if one went too far out into the Atlantic that he would fall off the edge of the world. I read it in textbooks in school, heard it from teachers and discussed it with friends. There is only one problem with this notion: it is not true.
You cannot find a half dozen authors in the Middle Ages who thought that the earth is flat. In fact, scholars in the Middle Ages followed the Greeks who believed that the earth was round. Now you might want to tell me that people opposed Columbus's trip across the Atlantic because they believed that he would fall off the edge of the earth. But the historical record is quite different. Columbus claimed that the earth was much smaller than others said. Those opponents of Columbus followed the calculations of Eratosthenes, the Greek who calculated the circumference of the earth within 2 percent. They said that Columbus and his men would die before they reached the Far East. And if there had not been two continents in between Europe and the Far East, he would have. (You can read up on this in Wikipedia's article on Columbus.) [Some of you have realized by now that this myth is actually about what myths that Medieval people were supposed to have had, but did not.]
There is another myth that I used to believe about old age. It came up in Sunday School recently. We were talking about how Abraham, Isaac and Jacob lived a very long time. (They lived 175, 180 and 147 years, respectively) One of my students had a confused look on his face and asked 'didn't people die at about age 25 in this time?' The answer to this question is unequivocally, no!
The idea that people in past ages died much earlier than we do comes from what we call 'life expectancy'. Life expectancy means that a person born today on average lives 'x' number of years. We know that in the Middle Ages people had a life expectancy of 35 to 45 years. In fact, two hundred years ago, it was about 45. We have misunderstood, however, what life expectancy means. It does not mean that people die of old age at this time. It means that many people die well before they reach old age. They died of diseases that we can cure now. They died of infections obtained through wounds, accidents, poor environmental conditions, and illnesses. Once we had antibiotics and better sanitation we began to live much longer. Many more people reach old age today.
Historical records clearly indicate that in all times and places there were some who reached the same age we can expect to live. In early biblical times, they lived even longer. One of the reasons for this is probably a higher oxygen content in the atmosphere. Scientists have found ancient air bubbles trapped in hardened liquids that show that in dinosaur days there was a lot more oxygen in the atmosphere than there is today. The higher oxygen levels allowed dinosaurs to grow to great sizes. It would cause us to live much longer and to be able to do greater things. (Build pyramids?) Before Noah's flood, people lived for hundreds of years. After the flood, people began to die sooner and sooner. It may have been because the oxygen levels were dropping over the whole world after the Flood(evidence that it was a worldwide catastrophe). By the time we reach Moses' day, old age sets in earlier and life expectancy is 70 to 80 (except for the early deaths that I mentioned above - sickness and accidents).
People during the Middle Ages in Europe lived shorter lives than they did in antiquity because health conditions were so bad. We should be careful about extrapolating. What is extrapolating? It means to reason like this: If people today live about 75 years and if they lived about 45 years in previous centuries, then people who lived in ancient times lived even shorter lives. So, the reasoning would be that the longer ago you lived, the shorter the average life span was. That is extrapolation. It generally does not work well. It leads to a poor understanding of things in the past.
So do not believe everything you hear. It is a modern error to always think that we are smarter or better off than in any time in the past.
One thing is not a myth: I am thankful for my wife just like she is thankful for me as she wrote on her Facebook wall.