Humans first made controlled use of fire about a million years ago, but there isn’t much evidence that it was used widely at that early date. A team of researchers from the University of Arizona and the University of Haifa examined the evidence of fire use at 11 Paleolithic sites in the Levant and found that it was not common until around 350,000 years ago. When and how fire came to be used by humans has become an area of renewed interest to paleoanthropologists. “There are all kinds of interesting evolutionary developments inherent in how fire is incorporated as an element of technology, and even of social life, that we haven’t really thought about because we were mainly concerned with the earliest use of fire,” says Steven Kuhn of the University of Arizona. Beyond just providing warmth, fire kept predators away and led to cooked food and better nutrition, and it also may have been a focal point for social activities. According to Kuhn, there is evidence that the way living spaces were organized changes when people adopt fire. Why this change in fire use occurred is a matter of conjecture. It could be that earlier than 350,000 years ago people were controlling and using naturally occurring fires, says Kuhn, and that only later did they learn to start fires on their own.

Beneath a stone carving of the Aztec earth goddess Tlaltecuhtli inside Mexico City’s Templo Mayor, archaeologists have found an offering containing a variety of artifacts and animal bones, including seashells, from all over the Aztec Empire. A new analysis shows that several of the shells come from mollusks that live on Mexico’s Pacific coast, a possible indicator that the Aztecs expanded their empire to that area during the reign of Ahuitzotl, between 1486 and 1502.

Researchers believe that Native Americans have been building the conical wooden shelters popularly known as wickiups, which usually leave no trace in the archaeological record, for at least 12,000 years. In the arid Mountain West, however, many of these structures, some of them recently dated to just hundreds of years ago, are still standing. The Colorado Wickiup Project, led by archaeologist Curtis Martin, has been documenting and dating these temporary dwellings, and has created a database of more than 400 in northwestern Colorado alone. Most were built by members of the Ute tribes, and offer clues to their history.

More than half the wickiup poles the project has thus far studied show, via tree-ring dating, that the wood was harvested after 1881. This was a major surprise, according to Curtis, because “1881 is when all Utes were said to have been removed to the reservations in Utah. But we can show they were here, and in great numbers, until at least 1917.” These wickiups, he says, are silent evidence of the last autonomous Utes, who have been overlooked by history.