A new study challenges a site that’s crucial to our understanding of how people got to the Americas. Decades ago, a site in Chile called Monte Verde was dated to about 14,500 years ago. That put to rest theories about the ancient Clovis people being the first to arrive. A new study, though, contends that Monte Verde may be much younger than believed, at about 8,000 years old. The researchers think changes to the landscape, including a stream wearing down the rocks, may have mixed older layers with new. But not everyone agrees with the findings. The study was published Thursday in the journal Science.