Europeans are known for cutting-edge design. But when it comes to stone tools, archaeologists had long considered early Europeans to be latecomers. The hand ax, for example, invented at least 1.5 million years ago in Africa, had not been sighted in Europe earlier than about 500,000 years ago. But new dating of two sites in Spain indicates that the earliest hand axes on the continent are nearly twice that old. The findings have important implications for our understanding of early human migrations.
Hand axes have sometimes been called the Swiss Army knives of the Stone Age world. They vary in shape and size, but most are at least roughly symmetrical, with one pointed and one rounded edge. Hand axes were very handy for butchering animals and cutting the stalks of tough plants. Yet although early humans began leaving Africa for Europe and Asia around the time the hand ax was invented, the tool does not show up until much later at most sites in Eurasia. Exceptions include 1.4-million-year-old 'Ubeidiya and 780,000-year-old Gesher Benot Ya'aqov, both in Israel, and 800,000-year-old Bose in China. In Europe, the earliest known hand ax site was 500,000-year-old Boxgrove on England's south coast.
To get a better handle on early tool use, geochronologist Gary Scott and geologist Luis Gibert of the Berkeley Geochronology Center in California set about dating two sites in southeastern Spain where hand axes had been found. Judging mainly by the level of sophistication of the hand axes, archaeologists had earlier estimated the age of the two sites--an open-air spot called Solana del Zamborino and a rock shelter called Estrecho del Quípar--at about 200,000 years.
Scott and Gibert redated the sites using a technique called paleomagnetism, which measures the magnetic polarity of minerals in buried sediments to determine their approximate age. Earth's magnetic field has periodically reversed its polarity. The last time this happened was 780,000 years ago, during an event called the Brunhes-Matuyama reversal.
When Scott and Gibert measured the magnetic polarity of sediment layers at Solana de Zamborino, where several hand axes and other tools had been unearthed during the 1970s, they found that the tools lay just above the layers that had undergone the Brunhes-Matuyama reversal, providing a new date for the hand axes of about 760,000 years ago. At Estrecho del Quípar, which has been under excavation since the 1990s and where hominin teeth, a hand ax, and other tools have been found, all of the sediment layers were below the Brunhes-Matuyama boundary. From the position of the artifacts in the sediment layers, they are at least 900,000 years old, the researchers report tomorrow in Nature.
Scott and Gibert argue that the existence of such ancient sophisticated stone tool technology in Western Europe shows that early humans were well established on the continent much earlier than many archaeologists have assumed, based on the few early hominin sites so far discovered and excavated.
Christian Tryon, a geoarchaeologist at New York University in New York City, says that the study provides "solid evidence" for early dates at the two sites. "The old dates for these hand axes really show how often we underestimate the technical expertise of the earliest European toolmakers."