A single tooth is changing how archaeologists think about the history of human evolution.
The tooth, a molar, is one of the last remnants of the earliest modern humans found in Europe, according to two papers published Monday by an international team of archaeologists, who found it among human remains, stone and bone tools, and pendants made from cave bear teeth, in Bulgaria’s labyrinthine Bacho Kiro cave.
“This is much older than anything else that we have found so far from modern humans in Europe,” said Jean-Jacques Hublin, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology at Leipzig in Germany, who led the team.
The molar is the largest surviving bone fragment from a group of very early Homo sapiens that was dated to between 44,000 and 46,000 years ago.
They push back the earliest confirmed arrival of Homo sapiens in Europe, and show they somehow shared the land for thousands of years with the heavily-built Neanderthals (Homo neanderthalensis) who were already there.
The finds also resolve a debate about distinctive tools and personal ornaments known as Bachokirian, after the cave.
These show new ways of using stone, bone and antler that became common among Homo sapiens many thousands of years later.
Similar items made by Neanderthals have been found elsewhere. But the new finds indicate those Neanderthals adopted the new ways of making them from early Homo sapiens.
Evidence from other sites suggests the people at Bacho Kiro cave were part of a “pioneer” wave of Homo sapiens that entered southern and central Europe up to 47,000 years ago from southwest Asia, Hublin said.
Their arrival was up to 8,000 years earlier than a wave of Homo sapiens that eventually spread across western Europe, and replaced the last Neanderthals about 39,000 years ago.
Homo sapiens also replaced other groups of early humans, such as the Denisovans who had populated much of Asia, at around the same time, he said.
“This is one of the most important periods of human evolution,” Hublin said. “This is when hominins like Neanderthals and Denisovans were replaced by modern humans.”
Hublin’s team has worked at Bacho Kiro cave since 2015. Parts of the vast limestone cave were opened to tourists in the 19th century and some archaeological work was done there in the 1930s and the 1970s. It is now one of Bulgaria’s most famous tourist caverns.
For the latest work, Hublin and his team broke down walls near the entrance built to keep tourists on the path.
The bones and artifacts they found were carefully dated with radiocarbon analysis, which measures how their carbon isotopes decay – giving the team vital information missing from the earlier excavations.
The radiocarbon dates closely match the dates calculated by Hublin’s team from the genetic material, or DNA, extracted from the human bones.
Before this, the oldest confirmed find of Homo sapiens remains in Europe were from Peştera cu Oase in Romania, and dated to around 41,000 years ago.
While Neanderthals were probably smarter than popular accounts suggest, it now seems they didn’t invent Bachokirian tools and ornaments on their own, said paleoanthropologist Richard Klein from Stanford University in California, who was not involved in the new research.
Instead, it’s likely they adopted this new style of tools and ornaments from early Homo sapiens, “presumably by imitation or observation.”
But the interactions between Neanderthal and early groups of humans in Europe remain unclear – although some Neanderthal genes are found in modern humans, indicating some interbreeding took place, he said.
So why did the Neanderthals die out, if they were capable of copying the technologies of the new arrivals?
“That's the ultimate question,” Klein said.