Did the early indigenous peoples of the rainforest look to the stars to measure time and mark the passage of the seasons? Archaeologists believe they did.
This photograph shows what is being called the tropical Stonehenge, a grouping of 127 granite blocks, each 10ft high and spaced at regular intervals around a grassy hilltop in northern Brazil. On the winter solstice, 21 December, the shadow of one of the blocks disappears, leading experts to believe the formation was used as a calendar.
"Only a society with a complex culture could have built such a monument," said Mariana Petry Cabral, of the Amapa Institute of Scientific and Technological Research.
Actually, not much new there.