Sophisticated tool-making skills more widespread than previously thought.
By Rex Dalton
Hand axes from southern Spain have been dated to nearly a million years old, suggesting that advanced Stone Age tools were present in Europe far earlier than was previously believed.
Acheulian axes, which date to at least 1.5 million years ago, have been found in Africa, and similar tools at least 700,000 years old have been found in Israel and China. But in Europe, sophisticated tool-making was thought to stretch back only around 500,000 years.
Cave sediment levels that included the two axes also held what some archaeologists believe may be small tools made using the so-called Levallois technique of shaping stone, known to have existed in Europe only about 300,000 years ago.
"Up to now, no one imagined this level of tool-making was going on in Europe about a million years ago," says Michael Walker, an archaeologist at the University of Murcia who has studied the region near Granada where the axes were found.
Homo neanderthalensis, Homo erectus and Homo heidelbergensis are all species known to be associated with Acheulian axes, which have two-sided cutting faces that were made of many types of stone for still-unconfirmed uses.
The Iberian axes, reported in Nature1 today, were found at two sites dated to at least 760,000 and 900,000 years old, respectively. Gary Scott and Luis Gibert of the Berkeley Geochronology Center in California dated the sites using palaeomagnetic analysis, which uses known changes in the orientation of Earth's magnetic field over time.
Thomas Wynn, a cognitive evolutionary biologist from the University of Colorado at Colorado Springs, says: "This [find] tells us some things about these early humans' brains, like the development of spatial conception. But not much, as cognitive ability changes very, very slowly."
For co-author Luis Gibert, the report is the culmination of years of field studies in the Quipar Valley, where his late father, Josep Gibert Clols, pioneered research. "This is an amazing site," says Gibert.
The Quipar Valley has historically been home to a lake environment of marshes and shallow lagoons. The Solana del Zamborino and Estrecho del Quípar caves in the valley, where the axes were found, were first thought to be only about 200,000 years old.
But after dates of stone flakes at a nearby location indicated they were much older, Gibert, now a postdoctoral researcher at the Berkeley centre, and Scott homed in on the caves' rich sediments.
In addition to the palaeomagnetic technique, Gibert notes that a record in rock layers of the remains of micro-mammals such as rodents, developed by Walker's team at Estrecho del Quípar, was crucial in confirming the dates. The Solana del Zamborino cave hadn't been studied in more than 30 years.
The older dates for the Spanish axes are now expected to generate new studies at other European rock shelters bearing Acheulian artefacts. But those studies may be hampered by the lack of appropriate sediments with which to identify palaeomagnetic polarity reversals, says Walker.