A mystery that's always fascinated me is how the ancient people of Easter Island moved the huge stone statues, called moai, across the island. I'm a fifty-year-old secondary school geography teacher in Valparaíso, Chile, so I suppose it's partly professional interest.
Easter Island is a tiny piece of land in the Pacific Ocean, thousands of kilometres from the mainland, and the statues were carved hundreds of years ago. There are hundreds of them, and some are as heavy as several lorries. They were carved in one quarry and then somehow transported to platforms all around the coast.
I first heard about it as a child, from a picture in an encyclopaedia my father kept on the top shelf. I remember staring at those enormous heads and asking him how people got them there. He said nobody knew, and I found that answer both annoying and thrilling.
What makes it so interesting to me is that it combines engineering, history and human cooperation. There are several theories. Some researchers think islanders rolled the statues on logs, while others believe they 'walked' them upright by rocking them from side to side with ropes, which sounds unbelievable but has been tested on models. The fact that there's still no complete agreement shows how much we don't know about the past. I also like that it reminds us not to underestimate earlier societies. People often assume ancient communities were primitive, but organising a project like that required planning, skill and teamwork. I use it in class every year, and my students always argue about it.