内容摘要：Republican presidential nominee former President Donald Trump is reflected in the bullet proof glass as he finishes speaking at a campaign rally in Lititz, Pa., Sunday, Nov. 3, 2024. (AP Photo/Matt Rourke)

Republican presidential nominee former President Donald Trump is reflected in the bullet proof glass as he finishes speaking at a campaign rally in Lititz, Pa., Sunday, Nov. 3, 2024. (AP Photo/Matt Rourke)

This photo provided by researchers shows fossils at the excavation site of Arroyo del Vizcaíno in Uruguay, where researchers have found evidence suggesting human occupation 30,000 years ago. (Martín Batallés via AP)This photo provided by researchers shows fossils at the excavation site of Arroyo del Vizcaíno in Uruguay, where researchers have found evidence suggesting human occupation 30,000 years ago. (Martín Batallés via AP)

Clovis is a site in New Mexico, where archaeologists in the 1920s and 1930s found distinctive projectile points and other artifacts dated to between 11,000 and 13,000 years ago.This date happens to coincide with the end of the last Ice Age, a time when an ice-free corridor likely emerged in North America — giving rise to an idea about how early humans moved into the continent after crossing the Bering land bridge from Asia.And because the fossil record shows the widespread decline of American megafauna starting around the same time — with North America losing 70% of its large mammals, and South America losing more than 80% — many researchers surmised that humans’ arrival led to mass extinctions.

A rib bone from a giant sloth thought to be burned by human-made fire, discovered in central Brazil and dated to 13,000 to 15,000 years ago, at the Smithsonian Institution in Washington, D.C. on July 11, 2024. (AP Video/Mary Conlon)“It was a nice story for a while, when all the timing lined up,” said paleoanthropologist Briana Pobiner at the Smithsonian Institution’s Human Origins Program. “But it doesn’t really work so well anymore.”

In the past 30 years, new research methods — including ancient DNA analysis and new laboratory techniques — coupled with the examination of additional archaeological sites and inclusion of more diverse scholars across the Americas, have upended the old narrative and raised new questions, especially about timing.

“Anything older than about 15,000 years still draws intense scrutiny,” said Richard Fariña, a paleontologist at the University of the Republic in Montevideo, Uruguay. “But really compelling evidence from more and more older sites keeps coming to light.”Food and Drug Administration, San Clemente, Calif. (21,450 square feet)

Indian Health Service-Bemidji, Sault Ste Marie, Mich. (1,100 square feet)Small Business Administration, Seattle, Wash. (12,867 square feet)

Forest Service, Silver City, N.M. (29,554 square feet)National Park Service, Somerset, Pa. (2,361 square feet)