Raw material procurement in northwest Sierra Morena during the Middle Palaeolithic: quartz exploitation at La Sima Cave (Constantina, Seville, SW Spain)
This study characterizes Middle Palaeolithic lithic procurement at La Sima Cave in SW Spain through geological mapping and microscopic analysis, revealing that human groups employed a dual mobility strategy utilizing nearby quartz outcrops (<10 km) and more distant Guadalquivir River terraces (25–30 km) for higher-quality quartzite and chert.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine a group of Neanderthals living in a cave called La Sima in southwestern Spain about 40,000 to 50,000 years ago. To survive, they needed to make stone tools to hunt and process food. This paper is like a detective story that tries to figure out where they got their rocks and how far they had to walk to get them.
Here is the breakdown of their investigation, explained simply:
1. The Main Ingredient: Quartz
The Neanderthals at La Sima were like a kitchen that mostly used quartz (a common, somewhat gritty stone) to make their tools. It was the "flour" of their toolkit, making up nearly 86% of everything they found.
- The Problem: Quartz is everywhere, but not all quartz is the same. Some is easy to shape; some is brittle and breaks badly.
- The Detective Work: The researchers took tiny slices of the ancient stone tools and looked at them under a microscope. They also took samples of quartz rocks from the hills surrounding the cave.
- The Match: Using a special chemical scanner (like a high-tech metal detector for rocks), they compared the "fingerprint" of the tools to the rocks outside. They found that the tools mostly matched rocks from two specific hills (called Las Majadillas and Malpicas) located about 6 to 7 kilometers (4 miles) away. This is a very short walk for a day trip.
2. The "Premium" Ingredients: Quartzite and Flint
While quartz was the daily bread, the Neanderthals also used a few tools made of quartzite and flint. Think of these as the "steak" or "specialty spices" of their toolkit. These stones are harder, sharper, and better for making complex tools.
- The Source: These premium stones didn't come from the nearby hills. Instead, they came from the Guadalquivir River, which is about 25 to 30 kilometers (15–18 miles) away.
- The Strategy: The researchers believe the Neanderthals didn't just wander aimlessly. They likely followed the river valleys, which acted like natural highways. Walking along a river is easier than climbing steep mountains. They would walk to the river, pick up the best river-worn stones, and bring them back to the cave.
3. The Map of Movement (The "Energy Budget")
The researchers used a computer map (GIS) to calculate how much energy it would take to walk from the cave to different rock sources.
- The "Easy Zone": The nearby quartz hills were in the "blue zone" of the map—easy to reach, low energy cost.
- The "Hard Zone": The river was further away, requiring more energy.
- The Conclusion: The Neanderthals had a two-part strategy:
- Daily Routine: Grab the easy, local quartz for everyday tasks.
- Special Trips: Occasionally make a longer, planned trip to the river to get the high-quality stones for special, complex tools.
4. What This Tells Us About Their Lives
The paper suggests these Neanderthals were smart planners, not just wandering randomly.
- They knew their landscape: They knew exactly which hills had good rocks and which rivers had the best ones.
- They saved energy: They didn't walk 30 miles just to get a rock if a 5-mile walk would do. They only made the long trip when they needed the "premium" stuff.
- They were adaptable: When the local rocks (quartz) were too brittle for a specific job, they had a backup plan to fetch better materials from the river.
Summary Analogy
Imagine you are cooking dinner. You usually use the cheap, local potatoes from your neighbor's garden (the quartz from the nearby hills) because they are easy to get. But sometimes, you need a really sharp knife or a specific spice to make a special dish. So, you plan a trip to the big supermarket down the road (the Guadalquivir River) to buy those premium items.
This paper proves that the Neanderthals at La Sima were doing exactly that: mixing their daily local supplies with occasional, strategic trips for high-quality resources.
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