Scientists say fossils unearthed in Morocco show early Homo sapiens roamed Africa 100,000 years earlier than previously thought. The discovery shakes up a long established consensus about the origins of our species.
The skull, teeth and bone fragments discovered near Marrakech are estimated to be about 300,000 years old, according to research published Wednesday in the journal Nature.
"This material represents the very root of our species, the oldest Homo sapiens ever found in Africa or elsewhere," said paleoanthropologist Jean-Jacques Hublin of Germany's Max Planck Institute for Evolutionary Anthropology, one of the scientists leading the research.
Until this point, the oldest known Homo sapien remains were from Ethiopia, dating back about 195,000 years. For that reason, East Africa has long been considered the evolutionary "Garden of Eden," where our species originated.
"The message we would like to convey is that our species is much older than we thought and that it did not emerge in an Adamic way in a small 'Garden of Eden' somewhere in East Africa," Hublin said.
There is broad scientific consensus that Homo sapiens originated in Africa. But these latest findings, the researchers say, suggest a "rather more complex picture," with primitive forms of the species likely dispersing across the entire continent 300,000 years ago.
Same face, different skull
The Moroccan fossils were discovered in a cave at a site called Jebel Irhoud between 2007 and 2011. They are believed to come from at least five individuals - three adults, one teenager and child of around 8 years old.
The skulls had faces and teeth matching those of humans today. "They are not just like us," Hublin said. But they had "basically the face you could meet on the train in New York."
One important difference, however, was their elongated braincases. According to the scientists, the longer skull shape shows that although the shape of our face was probably established very early on, our brain needed more time to develop into its current form.
"The story of our species in the last 300,000 years is mostly the evolution of our brain," Hublin said.
Dating back 300,000 years
The scientists concluded the remains came from hunter-gatherers. Near the bone fragments, archeologists found stone tools used to hunt and butcher animals, as well as evidence of extensive fire use.
Max Planck Institute archaeologist Shannon McPherron said an analysis of stone flints helped the scientists calculate the age of the adjacent human fossils. They used thermoluminescence - a technology that measures the exposure of stone minerals to radiation generated by heat - for example, from a cooking fire.
The evolutionary lineage that led to Homo sapiens is believed to have diverged from predecessors Neanderthals and Denisovans more than half-a-million years ago. But with few fossils to work with, the history of our species relies heavily on speculation.