Researchers have uncovered one of the earliest known manufacturing sites, a "tar factory" established by Neanderthals in Vanguard Cave, Gibraltar, dating back 65,000 years. This significant discovery sheds light on the advanced technological capabilities of Neanderthals.
The excavation revealed a small hearth, alongside Middle Paleolithic stone artifacts and plant residues, indicating that Neanderthals produced tar, likely used for crafting tools and weapons. To validate this technique, the research team replicated the process, successfully creating tar and constructing two spears in just four hours.
This finding provides evidence that Neanderthals employed tar as an adhesive to attach stone tools to wooden handles, a method predating modern human use of tar adhesives by over 100,000 years. The structure of the "tar factory" consisted of a round pit, measuring nine inches in diameter and three inches deep, with vertical sides and two one-inch-long trenches extending from it.
According to the researchers, this structure reveals a previously unknown method by which Neanderthals managed and utilized fire. Further analysis of the pit uncovered traces of guano from birds or bats, chemicals from burning materials, and remains of protective wax from rockrose plant leaves.
Importantly, this hearth was constructed approximately 20,000 years prior to the arrival of modern humans on the Iberian Peninsula. While it has been established that prehistoric peoples used materials like tar and resin as adhesives, the intricate process of its production had not been documented until this discovery.
To manufacture tar, Neanderthals filled the hearth with rockrose leaves, which, when heated, released a sticky substance. The pit was then sealed with wet sand to restrict oxygen, potentially mixed with guano for a stronger seal. A small fire was lit, heating the leaves to around 300 degrees Fahrenheit.
The two adjacent trenches were created when Neanderthals accessed the pit to retrieve the leaves before they cooled. Afterward, the leaves were squeezed to extract the tar, used to attach flint arrowheads to spears. Some experts remain cautious, suggesting that the findings do not conclusively demonstrate that the pits were exclusively for tar production, as the material could have served other purposes such as medicine or waterproofing.