Archaeological site of Atapuerca

Listen first. Wind moves through holm oak and dry grass on these low hills. Gravel crunches under your shoes. Then the path drops into a long, narrow cut in pale limestone, and the air cools a few degrees. The walls rise on both sides, grey and ochre, with metal scaffolding fixed to the rock. This is where much of what we know about the earliest Europeans was pulled out of the ground. It was done slowly, one brushstroke at a time.

You are standing in the Sierra de Atapuerca, a modest range of hills east of the city of Burgos in northern Spain. From a distance it does not look like much. Farmland, scrub, a few villages. But inside these hills is a maze of caves, shafts and fissures, formed as water dissolved the limestone over hundreds of thousands of years. Over time, many of those openings filled with sediment, animal bones and, sometimes, human remains. The hills worked as a natural archive.

Here is the first surprise. The trench around you is not ancient at all. It was dug in the late nineteenth century for a small mining railway that carried iron and coal through the hills. The engineers cut straight through several cave systems that had been sealed for ages. In doing so, they sliced open deep layers of sediment and left them exposed in the walls. The railway is long gone. The cross-section it created is the reason this place became famous.

Scientists noticed the potential of the trench and the nearby caves in the twentieth century. Systematic excavation began in the late 1970s, after a jawbone was found deep inside one of the caves. Since then, a large research team has returned almost every summer. For decades the project has been led by three Spanish researchers: Juan Luis Arsuaga, José María Bermúdez de Castro and Eudald Carbonell. Today students and specialists from many countries work on the scaffolding you can see.

One of the key sites along this trench is called Gran Dolina. Dolina is a geological word for a sinkhole. In the 1990s, excavators found human bones here that were around 800,000 years old. The fossils looked different from anything already known. In 1997 the team gave them a new species name: Homo antecessor, which means something like the explorer, or the one who came before. It is one of the oldest known human species in Europe.

The second surprise is darker. Some of those Gran Dolina bones carry cut marks from stone tools. The marks match the way animals were butchered for meat. Many researchers interpret this as some of the oldest evidence of cannibalism in human history. Why it happened is still debated. It may have been about food, or about competition between groups. The bones themselves cannot tell us the motive, only the action.

Another site on the trench, Sima del Elefante, the Pit of the Elephant, goes back even further. In 2007 the team announced part of a human jaw from here, more than a million years old. At the time it was the oldest human fossil found in western Europe. More recently, researchers reported fragments of a face from the same deposit, also well over a million years old. Each new find pushes the human story in Europe deeper into the past.

The most extraordinary site is not on the trench. It lies inside a cave system called Cueva Mayor, at the bottom of a deep vertical shaft. Its name is Sima de los Huesos, the Pit of Bones. Visitors cannot go down there. Reaching it means crawling and climbing through narrow passages for a long time. Excavators work in cramped, damp conditions, often by headlamp, lifting sediment out in bags.

From that pit, the team has recovered thousands of human bone fragments. They belong to at least twenty-eight individuals, men, women and young people. The remains are roughly 430,000 years old. Their features look like early relatives on the line that led to the Neanderthals. It is one of the largest collections of fossil humans from this period found anywhere in the world. Studying it has shown scientists how one ancient population lived, aged and died.

The pit also held a single stone hand axe, made of reddish quartzite. The researchers nicknamed it Excalibur. It was found among the bones, with no sign of daily life around it. Some scientists believe the bodies were placed in the shaft on purpose, and the axe with them. If that is true, it would be a very early sign of ritual behaviour around death. Others are more cautious. The question remains open, and that is part of what makes this place so interesting.

Because of all this, the Sierra de Atapuerca was added to the UNESCO World Heritage List in 2000. Visits to the excavation area are guided and leave from visitor centres in the nearby villages. Plan around that, and book ahead in summer. Near the village of Atapuerca there is also an experimental archaeology park, where guides show how early humans made fire, shaped stone tools and hunted. In Burgos, the Museum of Human Evolution displays many of the original fossils.

The hills hold more recent layers of history too. The village of Atapuerca sits on the Camino de Santiago, the old pilgrim route to Santiago de Compostela. You may see walkers with backpacks and scallop shells passing along the road. In 1054, a battle between the kings of Castile and Navarre was fought on these slopes. So even in the medieval period, this quiet ground was a meeting point for people from far away.

Before you leave the trench, look again at the walls. The bands of colour are layers of time, laid down one on top of another. Small labels and grid markers show where each find was recorded. In summer you might see the team at work, brushing, sieving, numbering. Every bag of earth is checked. A tooth the size of a fingernail can change a chapter of a textbook.

As you walk back up the path, notice the sound of the wind again, and the wide open view over the fields toward Burgos. People have looked across this same landscape for more than a million years. They hunted here, sheltered here and buried their dead here. The hills have changed very little on the surface. What has changed is what we know about what lies beneath them.