Humans originated in Africa, but when our first ancestors left the continent and how they spread around the world is hotly debated by archaeologists.
Two cave holes discovered in northern Laos indicate that Homo sapiens, our species, were living in the area around 86,000 years ago, according to a new study. This discovery challenges the prevailing notion that humans’ path around the world was linear and occurred in a single wave some 50,000 to 60,000 years ago.
said study author Kira Westaway, assistant professor at Macquarie University in Australia, via email.
DNA analysis of current human groups has supported the hypothesis that the first modern humans left Africa around 50,000 to 60,000 years ago, and archaeologists believe our early ancestors likely followed the coasts and islands across Southeast Asia toward Australia.
However, an increasing number of ancient human remains unearthed in China and the Levant show that this chapter of the human story is more complex than first thought.
The migration that occurred 50,000 to 60,000 years ago “may not have been the first of its kind contributing to our current gene pool,” Westaway said. “There may have been previous migrations that were not successful and therefore did not contribute their genes to our modern population.”
Two Laos fossils – part of the shin bone and part of the front of the skull – were found in Tam Pa Ling Cave. The archaeological site was rediscovered in 2009 when another partial skull was discovered.
In addition to the latest finds, two jawbones, a rib and a phalanx were also unearthed at the site, and the physical features of the remains all indicate that they belong to early modern humans.
Determining the date of excavations from the site has proven difficult. They were too old for radiocarbon dating, which could only date remains from about 46,000 years ago. The cave is also part of a UNESCO World Heritage Site. Which means the human fossils cannot be directly dated due to Laos laws protecting the area, according to Westaway.
Instead, the team involved in the study, which was published Tuesday in the journal Nature Communications, used two different methods to estimate the age of the fossils.
The researchers measured the luster in the quartz and feldspar minerals in the sediment layer, a method that reveals how long it has been since a material containing crystalline minerals was heated or exposed to sunlight.
As the dig progressed deeper, they also found two animal teeth in the same layer as the human remains and dated them both by measuring the radioactive decay of uranium isotopes—chemical elements found in tooth enamel—in a technique called electron resonance dating. .
The two fossils have been estimated to be around 68,000 to 86,000 years old, with the shinbone fragment being the older find.
In addition to calling into question the timeline of early human migration, the site also challenges conventional thinking that early voyages of humans in the region would have included detours of coastlines and island sites such as Sumatra, the Philippines, and Borneo.
The highlands region in the heart of mainland Southeast Asia was and still is heavily forested, about 1,100 meters (3,609 feet) high and at least 300 kilometers (186 mi) from the sea.
“The fascinating part of this research is the cave site. We know that hominins tended to move along inland river valleys, but this site confirms our suspicion that early Homo sapiens had the ability to adapt and spread through higher forest areas much earlier than Predictably,” Westaway explained.
Archaeologists believe the cave was occupied for nearly 50,000 years, and recent discoveries underscore the area’s exciting potential for paleoanthropology.
At a nearby site, known as Cobra Cave, a tooth believed to belong to a Denisovan, an elusive human, was found. However, this tooth is 70,000 years older than the oldest Tam Pa Ling remains, so there is no evidence of the two human species intermingling or coexisting, Westaway said.
The world’s oldest pictorial rock art is found in caves in Indonesia, and extinct human species, including Homo floresiensis and Homo luzonensis, have been found on islands in Indonesia and the Philippines.
The team expects to discover more human fossils from the area.
The Tam Pà Ling site is one of five other sites (that have been found) In that karst mountain all contain human evidence, Westaway said.
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