Neanderthals may have built a hearth specifically to make tar

Neanderthals really knew their way around fire. In a sea cave sheltered from Gibraltar’s raging winds, our ancient cousins ​​created a hearth capable of making tar from nearby plants, new research suggests.

Previous research has shown that Neanderthals used tar as an adhesive to make weapons, and that they used fire for heating and cooking (SN: 31.8.17). However, the new discovery, reported on November 12 at Quaternary Science Reviewssuggests that Neanderthals designed specialized fire structures to make their own tar.

“We didn’t expect to find it,” says Juan Ochando Tomás, a botanist at the University of Murcia in Spain. But after gathering evidence from various scientific disciplines, researchers were able to identify the structure as a hearth and realize that it was indeed made by Neanderthals.

Ochando Tomás’ team found a small pit in a layer of sand, silt, and clay dating to about 65,000 years ago in a cave known to have been inhabited by Neanderthals (SN: 22.9.08). The researchers performed a series of chemical and visual analyzes on the contents of the pit and the surrounding sediments.

Their results suggest that the pit contains charcoal, pollen, and chemical compounds that indicate the burning of resinous plant material, along with yellow crystals that they interpret as possible tar. The tar was apparently made from gum resin (Cistus ladanifer), a plant that grows in nearby bushes.

Based on their findings, the researchers recreated the structure by filling a hole with roses, sealing it with sand and soil, and setting a fire on top to vaporize the plants. After several attempts, the team was able to make enough pitch to make two spears from flint and olive wood.

The structure is an “odd” for the period, says archaeologist Andrew Sorensen, who was not involved in the study. Most Neanderthal hearths were much simpler, he says, and fire use by ancient hominids appears to have been less frequent during this time period.

Initially skeptical of the study’s conclusions, Sorensen says he was impressed by the analysis of the pit’s contents and the recreation. The find shows that Neanderthals may have used one of the most complex and efficient methods of making tar, he says, and adds another possible glue to the short list of those they used to make tools.

“My main curiosity now is whether they are able to find residues in stone tools in situ that match the physical and chemical signatures of rose tar,” says Sorensen, of Leiden University in the Netherlands. “I think that would do a lot to assuage any remaining skeptics.”