Trying once more via the magnifying lens on the fossil’s floor, one in every of us, Sabrina Curran, took a deep breath. Illuminated by a powerful gentle positioned almost parallel to the floor of the bone, the V-shaped strains have been clearly there on the fossil. There was no mistaking what they meant.
She’d seen them earlier than, on bones that have been butchered with stone instruments about 1.8 million years in the past, from a web site known as Dmanisi in Georgia. These have been minimize marks made by a human ancestor wielding a stone instrument. After gazing them for what felt like an eternity − however was most likely only some seconds − she turned to our colleagues and mentioned, “Hey … I think I found something.”
What she’d noticed in 2017 was our crew’s first proof that hominins butchered a number of animals on the web site of Grăunceanu, in Romania, at the least 1.95 million years in the past. Earlier than this discovery, these different minimize marks from Dmanisi have been the oldest well-dated proof in Eurasia of the presence of hominins − our direct human ancestors.
Different scientists have reported websites in Eurasia and northern Africa with both hominin fossils, stone instruments or butchered animal bones from round this time. Our not too long ago revealed analysis provides to this story with well-dated, verified proof that hominins of some variety had unfold to this a part of the world by round 2 million years in the past.
Romanian web site with fossilized animal bones
A Nineteen Sixties photograph of fossil bones earlier than they have been excavated from the bottom at Grăunceanu, Romania.
Emil Racoviță Institute of Speleology
Slightly background on Grăunceanu: This open-air web site was initially excavated within the Nineteen Sixties, and researchers discovered hundreds of fossil animal bones there. It’s one of many best-known Early Pleistocene websites in East-Central Europe. Most of the fossil animal bones are fairly full and on the time of excavation lay collectively as they have been positioned in life. The unique deposition was known as a “bone nest” due to how densely packed the bones have been.
In case you have been to face on the hillside surrounding Grăunceanu virtually 2 million years in the past, it might possible have appeared acquainted: a river channel surrounded by a forest that fades into extra open grasslands to the foothills. Often that river floods its banks, inundating the valley with wealthy soils, offering vitamins for the vegetation that the resident animals feed on. All fairly acquainted, till you look extra carefully at these animals: ostriches, pangolins, giraffes, saber-toothed cats and hyenas − in Europe!
It’s the fossil bones of those historical animal inhabitants that have been excavated at Grăunceanu. Sadly, many of the excavation information and provenance information for the location have been misplaced. Even with out these, although, the Grăunceanu fossils are so remarkably preserved that they provide up a wealth of paleontological data.
A number of years after discovering these first minimize marks, our crew, together with organic anthropologist Claire Terhune, zooarchaeologist Samantha Gogol, and paleoanthropologist Chris Robinson, spent a number of weeks fastidiously finding out all 4,524 Grăunceanu fossils, in search of extra marks.
We examined all surfaces of each fossil bone with a magnifying lens and low-angled gentle. Most of those fossils have root etching on them − sinuous, shallow, overlapping marks made by plant roots that grew close by. However every time we noticed a linear mark that appeared attention-grabbing, we took an impression of that mark with dental molding materials.
Briana Pobiner and Claire Terhune take molds of marks of curiosity on Grăunceanu fossils.
Sabrina Curran
Confirming they’re minimize marks
We will’t return in a time machine to look at when these marks have been made. Sure, historical human butchers wielding stone instruments would go away marks on bone. However mammalian predators or crocodiles might additionally depart marks with their sharp tooth. Sediments in rivers might scratch any bones rolling round within the water. Massive animals strolling throughout the panorama might transfer and scrape bones with their steps.
So how can we be assured that they’re minimize marks? That’s the place our zooarchaeologist collaborators Michael Pante and Trevor Keevil got here in.
Shut-up of a cut-marked bone from Grăunceanu, Romania.
Sabrina Curran
Inside the previous decade, Pante developed a novel technique for figuring out the supply of marks left on bones. Step one is capturing exact 3D measurements of the mark impressions utilizing a complicated microscope known as a noncontact 3D optical profiler.
Then they evaluate the 3D form information from the traditional marks with a reference set of 898 marks on fashionable bones made by identified processes, together with stone instrument butchery, carnivore feeding and sedimentary abrasion.
This new technique provides to the extra qualitative, descriptive standards many researchers, together with our crew, use to make mark identifications. As an illustration, we think about issues corresponding to mark location: Is the mark close to a muscle attachment web site, the place you would possibly anticipate finding a minimize mark if a hominin have been eradicating meat from a bone?
Primarily based on our analyses, we decided that 20 Grăunceanu fossils are marked by cuts, with eight displaying high-confidence minimize marks. Most of these marks are on fossils of hoofed animals, together with a couple of deer; one is a small carnivore leg bone. Once we might determine the kind of bone, the minimize marks are all the time in anatomical areas in keeping with slicing meat off bones.
Courting the location
Whereas the fossil species current may give us a tough age estimate of the location, we used uranium-lead (U-Pb) relationship to get extra exact age data. This method depends on the truth that naturally occurring uranium decays over lengthy however well-known intervals of time to finally rework into lead. Geologists use the ratio of those two parts like a radiometric clock to find out how previous one thing is.
When one in every of us, Virgil Drăgușin, requested geochemist Jon Woodhead to make use of U-Pb relationship to estimate the age of the Grăunceanu fossils based mostly on a number of small tooth fragments, he was reluctant. Tooth don’t normally work nicely for this relationship approach. However he agreed to a take a look at run, and to his shock the tooth he tried labored very nicely.
Collectively along with his colleague John Hellstrom, they calculated a way more exact date for the location. We now know the Grăunceanu web site is older than 1.95 million years.
All of this information collectively − the very well-calibrated and tightly clustered dates of the specimens plus at the least 20 cut-marked bones verified each by qualitative and quantitative strategies − offers very dependable proof that hominins have been certainly in Eurasia by at the least 1.95 million years in the past, though there are not any hominin fossils from Grăunceanu.
An artist’s reconstruction of the Early Pleistocene panorama round Grăunceanu.
Emi Olin
Generally once we look via our magnifying lenses, it virtually appears like we are able to peer into the previous. That’s unimaginable − however we are able to piece collectively strains of proof to color a clearer image of what occurred prior to now at Grăunceanu.
Now, imagining the view 1.95 million years in the past, we see scenes of deer cautiously consuming from the river, majestic mammoths within the distance, a herd of horses grazing, a saber-toothed cat stalking a big monkey, a bear instructing her cubs to hunt … and a small group of hominins butchering a deer.
