Early Humans Liked Jerky Too, Ancient Jaws Suggest

A handful of ancient human jaws were left in a box of animal bones at a Malaysian museum for almost 60 years before scientists finally realized they were human a few years ago.

Now, these fragments could be a clue to the diets of early modern humans living in the tropical rainforests around Borneo's Niah caves, researchers writing in the journal PLoS ONE reported in a study released Wednesday. Our Southeast Asian ancestors, they think, may have had a taste for jerky.

Darren Curnoe from the University of New South Wales, Australia, and colleagues studied fragments from three ancient mandibles to learn more about the lives of early humans. Direct uranium-series dating revealed two were aged at least 11,000 and 10,000 years old, respectively. The third jaw—which was smaller and more rugged than the others—could be up to 30,000 years old.

The team said the tough life of its owner might be reflected in the features of this smaller jaw. Its owner they estimated was small too. Its gums might have chowed down on chewy palm plants and dried meat in response to a challenging rainforest environment, they reported.

Tropical rainforests are some of the hardest places foraging humans can live, Curnoe told Newsweek. "Most of the food is high in the canopy, and what is on the ground is often difficult to catch or to eat and frequently is toxic or very fibrous and requires a lot of processing to make it edible."

The distinctive features of the older jaw, he said, probably signal dietary shifts linked to a changing climate. 30,000 years ago, the Earth was facing the last stretch of the Ice Age. But 18,000 years ago, our planet started heating up. Glaciers stopped advancing, sea levels rose and huge swathes of land flooded over the next few thousand years. Ultimately, "[Environmental] changes caused major shifts in the forest cover and plant and animal communities around Niah Caves and even sea levels in the South China Sea, with the coastline ranging from nearby to the caves to more than [60 miles] away," he said.

Dried or cured meat can last for short periods of time, he added. Without the luxury of a modern fridge, it might make up for unreliable animal sources in the last few thousand years of the Ice Age.

Read more: Ancient human footprints are oldest ever found in North America

But not everyone is convinced by the team's efforts. David Daegling, an anthropologist at the University of Florida, questioned some of the methods behind the research. He told Newsweek: "Their method of estimating size...is known to be a highly inaccurate reflection of bone mass and distribution."

A number of factors beyond its owner's diet could explain the peculiarities of the older jaw, he added. By the researcher's logic, he said, we should expect a puppy fed a modern human diet to develop a human-looking jaw as an adult. "That we never see this tells us something about that assumption."

But in spite of its limitations, he added, it's good to see reliable dating from the fossils themselves.

Read more: Out of Africa: 90,000-year-old human finger points to much earlier migration

Archeologists have uncovered hundreds of human fossils from the Niah Caves. Humans have used the site for at least 50,000 years, from hunter-gatherers to early farmers, to the Iron Age people that used the caves as cemeteries, Curnoe told Newsweek. "It has some of the earliest evidence for modern humans—people just like us today—who settled Southeast Asia from Africa as they spread across Asia and into New Guinea and Australia more than 50,000 years ago," he said.

Today, he added, it's known for the swallow nests used in bird's nest soup. Dried meats, he added, are still popular in Borneo today.