At the same time, discoveries elsewhere in Brazil are adding to the mystery of how the Americas were settled.

In what may be another blow to the Clovis model of humans’ coming from northeast Asia, molecular geneticists showed last year that the Botocudo indigenous people living in southeastern Brazil in the late 1800s shared gene sequences commonly found among Pacific Islanders from Polynesia.

How could Polynesians have made it to Brazil? Or aboriginal Australians? Or, if the archaeologists here are correct, how could a population arrive in this hinterland long before Clovis hunters began appearing in the Americas? The array of new discoveries has scholars on a quest for answers.

Reflecting how researchers are increasingly accepting older dates of human migration to the Americas, Michael R. Waters, a geoarchaeologist at Texas A&M University’s Center for the Study of the First Americans, said that a “single migration” into the Americas about 15,000 years ago may have given rise to the Clovis people. But he added that if the results obtained here in Serra da Capivara are accurate, they will raise even more questions about how the Americas were settled.

“If so, then whoever lived there never passed on their genetic material to living populations,” said Dr. Waters, explaining how the genetic history of indigenous peoples links them to the Clovis child found in Montana. “We must think long and hard about these early sites and how they fit into the picture of the peopling of the Americas.”