Researchers have uncovered the remains of two Ice Age infants in Alaska's interior, a discovery archaeologists call the youngest human remains from that era found in northern North America.

The remains dating back about 11,500 years offer a new glimpse into ancient burial practices, the Fairbanks Daily News-Miner reported Tuesday.

Researchers have explored a large sand dune for nearly a decade at a dig site known as the Upward Sun River southeast of Fairbanks. In 2010, archaeologists found the partly cremated remains of a 3-year-old child.

The babies' remains were discovered last year about 15 inches below in the same area. The bones are well preserved and appear to belong to one child who was stillborn and another who died soon after birth. The three children appear to have died during the same summer, according to researchers.

The infants were buried with stone spearheads and darts. Also found at the site were salmon bones.

"Every bit of new information we're gathering from Upward Sun and other sites really show a sophisticated subsistence economy," said University of Alaska Fairbanks researcher Ben Potter, whose team led the dig. Potter details the 2013 discovery in a new report published in the Proceedings of the National Academy of Sciences, according to the newspaper.

The infants are clearly Native American, according to Liverpool John Moores University researcher Joel Irish, who participated in the project. Researchers hope to follow up with DNA analysis to determine the gender and whether the babies were related, Irish said.

For the project, archaeologists worked with the Tanana Chiefs Conference and local tribes to set up rules on handling the remains.

The project received the backing of Jerry Isaac, who was the Tanana Chiefs Conference president at the time of the dig. Disturbing ancient burial sites is controversial, but Isaac said the knowledge gained could provide important links to Athabascan history. He is particularly interested in his ancestors' subsistence practices.

"The reason that personally I've supported it is one of curiosity and one of proof that our Native diets have connection to our health and well-being," he said.

Much more work remains at the dig site, according to Potter.