Archaeologists excavating at Tam Pa Linh Cave in Northern Laos / Kira Westaway
Published Wednesday 2023.06.14 19:21 JST
(CNN) Humans originated in Africa, but archaeologists have long debated when our earliest ancestors left the continent and how they spread around the world. I agree.
Two fossils unearthed in a cave in northern Laos, Southeast Asia, show that modern humans (Homo sapiens) lived there about 86,000 years ago. A new research paper published in the journal Nature Communications on the 13th revealed. The findings challenge the widely held theory that human ancestors migrated in a single wave around the world in straight lines about 50,000 to 60,000 years ago.
“While this early migration may have been unsuccessful, that doesn’t change the fact that Homo sapiens arrived at the site at that time, which is a remarkable feat,” said study author Macquarie of Australia. Responded to email request.
Current human DNA analysis supports the hypothesis that early humans left Africa about 50,000 to 60,000 years ago. Traditional archaeologists believe that early humans probably migrated along coastlines and islands to Asia and Australia.
However, the discovery of ancient human fossils in China and the Levant (the eastern coastal region of the Mediterranean Sea) suggests that human history during this period was more complex than first thought.
The 50,000 to 60,000-year-old migration that affects the human gene pool today may not have been the first, Westaway said, and may have occurred earlier. The migration didn’t go well, so it doesn’t appear to be genetically affecting humans today.
The two fossils found in the Tampalin Cave in Laos are fragments of a leg bone and the front part of a skull. The cave is an archaeological site discovered in 2009 when part of another skull was unearthed.
In addition to this discovery, two jaw bones, a rib and a finger bone were unearthed in the cave.
Dating local fossils has been difficult. The fossils are about 46,000 years old and can be determined by radiocarbon dating, and since the cave is part of an area registered as a World Heritage Site, it is possible to directly measure the age of the human fossils that came out of it in the same way that you cannot. That’s because Lao law protects the area, Westway said.
The research team used two different techniques to estimate the fossil’s age.
The researchers measured the luminosity of quartz and feldspar contained in the sediment layers. This reveals when these crystalline minerals were heated by the sun.
During the excavation, two animal tooth fossils were also found in the same layer as human fossils. The researchers determined the fossil’s age 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.
After verification, the age of the two fossils is speculated to be 68,000 to 86,000 years ago. The bones of the lower extremities appear older.
The discovery not only speeds up the date of early human migration, but also challenges previous theories that humans migrated along the coasts and islands of Southeast Asia.
The cave at the site is a high plateau, densely forested area in the interior of Southeast Asia. The altitude is about 1100 meters. At least 300 kilometers from the sea.
The location of the cave was an interesting part of the study, Westway explained. “These places turn our doubts into beliefs. For a while, I doubted 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 has continued for nearly 50,000 years.