See here the principle at work how humans conveniently forget their biggest atrocities and other failures, and why the same kinds of war perdiods keep on recurring every 80-120 years or so.

@Vincent I guess it's the same principle. It's amazing how quickly knowledge fades really. Information tech doesn't seem to change this.

In Denmark we have these graves from the stone age, jættestuer aka. "jotun rooms" or "giant rooms". It seems that people simply forgot what it was and started to make up stories about them being homes of giants. I think it wasn't before the 1800s people started studying them and found out they were in fact graves.