Archaeological Discovery Challenges Theory of Early Human Migration: Fossils Found in Laos Suggest Earlier Arrival in Asia

2023.06.14 Wed posted at 19:21 JST

（ＣＮＮ） Humans originated in Africa, but archaeologists have long debated when our earliest ancestors left the African continent and how they spread throughout the world. I’m in.

Two fossils unearthed in a cave in northern Laos in Southeast Asia suggest that modern humans, Homo sapiens, lived there about 86,000 years ago. A new research paper published in the journal Nature Communications published on the 13th revealed. The findings challenge the widely held theory that human ancestors migrated around the world in a straight line, occurring in a single wave some 50,000 to 60,000 years ago.

“While this early migration may not have been successful, it does not change the fact that Homo sapiens reached the site by that time period, which is a remarkable feat,” said Australia’s Macquarie, the study’s author. Kira Westaway, an associate professor at the university, responded to an email request.

Current human DNA analysis supports the hypothesis that early humans left Africa about 50,000 to 60,000 years ago. Traditional archaeologists have assumed that early humans likely migrated along coastlines and islands toward Asia and Australia.

However, the discovery of ancient human fossils from China and the Levant (the eastern coastal region of the Mediterranean Sea) reveals that human history during this period is more complex than originally thought.

The 50,000 to 60,000-year-old migration that affects today’s human gene pool may not have been the first, Westaway said, and may have occurred at earlier ages. The migration didn’t go well, so it doesn’t appear to have affected the genetics of today’s humans.

Archaeologists began excavating caves more than a decade ago

Two fossils found in Tam Pa Linh cave in Laos are a fragment of a leg bone and a front part of a skull. The cave was an archaeological site discovered in 2009, when parts of another skull were unearthed.

In addition to this discovery, two jawbones, a rib and a finger bone were also excavated from the cave.

Dating local fossils has been difficult. The fossils are older than around 46,000 years, which can be determined by the radiocarbon dating method, and the cave is part of the area registered as a World Heritage Site, and the age of the human fossils that came out of it can be directly measured by the same method. you can’t. That’s because Laotian law protects the area, Westaway said.

The research team used two different techniques to estimate the age of the fossils.

The researchers measured the luminescence of quartz and feldspar contained in sedimentary layers. This reveals how long these crystalline minerals have been heated by the sun.

During the excavation, two fossils of animal teeth were also found in the same stratum as the human fossils. The researchers dated the fossils by measuring the radioactive decay of uranium isotopes. Uranium is a chemical element found in tooth enamel. This technique is called electron spin resonance (ESR) dating.

Early humans are believed to have lived in caves for nearly 50,000 years.

As a result of verification, the age of the two fossils was estimated to be 68,000 to 86,000 years ago. The bones of the lower limbs appear to be older.

The discovery not only hastened the date of early human migration, but also challenged previous theories that they migrated along the coasts and islands of Southeast Asia.

The cave at the scene is a highland, dense forest area located inland in Southeast Asia. The altitude is about 1100 meters. At least 300 kilometers from the sea.

Westaway explains that the location of the cave is a fascinating part of the study. “These places turned our suspicions into convictions. For some time, I suspected that early Homo sapiens had the ability to adapt and live in high-altitude forests much earlier than previously thought. I was there,” he said.

Archaeologists believe that life in the cave lasted nearly 50,000 years.