Spanish fossils may represent unknown ancient human species

By Will Dunham

(Reuters) - Scientists have unearthed in Spain fossilized facial bones roughly 1.1 million to 1.4 million years old that may represent a previously unknown species in the human evolutionary lineage - a discovery that rewrites humankind's early history in Europe.

The fossils from the Sima del Elefante cave site near the city of Burgos comprise fragments spanning 80 percent of the left side of an adult individual's middle face, including parts of the cheekbone and upper jaw with the nasal structure. They are among the oldest-known human fossils from Europe.

The researchers nicknamed the fossil "Pink," honoring the band Pink Floyd.

Pink's facial anatomy was more primitive than that of Homo antecessor, a species known to have inhabited Western Europe roughly 850,000 years ago whose slender midface resembled modern people. Pink possessed a more projected and massive midface than Homo antecessor, and displayed some similarities to - but also differences with - Homo erectus, thought to be the first human species to have migrated out of Africa.

The researchers said the fossils were not complete enough to conclude that Pink belonged to a yet-unnamed ancient human species but said this was a real possibility. They assigned the fossil the provisional name Homo affinis erectus in recognition of its affinities to certain Homo erectus traits.

"These findings open a new line of research in the study of human evolution in Europe, as they introduce a new player in the early occupation of Europe," said archaeologist Rosa Huguet of the Catalan Institute of Human Paleoecology and Social Evolution (IPHES-CERCA) in Spain, lead author of the study published on Wednesday in the journal Nature.

"When we have more fossil remains, we will be able to say more about this species," Huguet said.

Our species Homo sapiens did not appear until roughly 300,000 years ago in Africa, later migrating worldwide, including into Europe. Homo erectus first appeared in Africa roughly 1.9 million years ago, with body proportions similar to modern people. Homo antecessor also had modern body proportions as well as modern-looking facial anatomy.

Pink's midface resembles Homo erectus with its flat and underdeveloped nasal structure, unlike the prominent nasal bone structure of Homo antecessor and Homo sapiens.

"Homo antecessor has a modern-like midface, very similar to that of Homo sapiens. In contrast, the midface found at the Sima del Elefante site has a combination of features shared with Homo erectus and others that are derived and not present in Homo erectus," said paleoanthropologist and study senior author José María Bermúdez de Castro Risueño, co-director of the Atapuerca Project focused on human evolution.

Little is known about Europe's earliest human residents. There are fossils commonly attributed to Homo erectus dating to 1.8 million years ago at a Caucasus site in Georgia called Dmanisi on the fringes of Europe. There also are stone tools dating to 1.4 million years ago from western Ukraine, and bones with cut marks, suggesting the use of stone tools to butcher animal carcasses, dating to 1.95 million years ago from Romania.

At the Sima del Elefante site, researchers previously recovered a jawbone fragment estimated at 1.2 million years old, though the species was undetermined. The Pink fossils found in 2022 were recovered in a deeper - thus older - layer at the same site. A child's molar dating to approximately the same time is known from a site near Granada in Spain, with the species also unclear.

"There are very few sites with human fossils corresponding to the first settlers of Europe," said archaeologist and study co-author Xosé Pedro Rodríguez-Álvarez of the University of Rovira I Virgili in Spain.

Pink is older than any known Homo antecessor remains. And Pink's species, according to the researchers, may belong to a population that reached Europe during a migration predating that of Homo antecessor.

"We do not know if they could have coexisted for a short period of time or if they never lived together," Huguet said.

Discovered nearby Pink were simple quartz and flint tools and animal bones with cut marks indicating butchery.

The researchers have not been able to reconstruct Pink's full face because of the incompleteness of the fossils. Diligent work was needed to assemble the fragments to reveal the midface, combining traditional conservation and restoration methods with sophisticated imaging and 3D analysis. Pink's gender remains unclear.

"There are many questions to be answered, and this find helps to write a new page in the history of human evolution," Bermúdez de Castro said.

(Reporting by Will Dunham in Washington, Editing by Rosalba O'Brien)