Stone tools reveal human adaptability

April 18, 2025

Archaeology

Ismael Sánchez-Morales, PhD
Curator of Anthropology, Arizona Museum of Natural History

Humans are characterized by extreme behavioral adaptability, a trait that has allowed our species to populate virtually every region of the world. This exceptional flexibility was essential for early Homo sapiens to spread first within Africa and later into new continents. The behavioral plasticity of early humans provided them with the necessary resourcefulness to overcome geographical and environmental barriers such as deserts, tropical forests, and changing landscapes by adapting their subsistence strategies accordingly. 

However, it is not clear when, where, and how this adaptability of behaviors originated. My research, funded in part by The Leakey Foundation, seeks to understand the adaptability of the economic behaviors of the Middle Stone Age, or MSA, hunter-gatherers of Northwest Africa. This region is at the center of recent research aimed at providing answers to these questions. 

Stone tools reveal adaptability, behavior, and decision-making

My research explores the variability of the stone tool evidence recovered from multiple cave sites situated in diverse landscapes of Morocco. Stone tools can reveal a great deal about the economic decisions of the foraging groups that produced them, such as the activities they conducted at a particular location or how they moved about in the landscape. By exploring the variability of assemblages of stone tools across space and time, we can gain insights into the behavioral adaptability of the people who created them. 

My article “Reassessment of the Lithic Assemblage from Layer 6 of Mugharet el’Aliya: Site Use and Mobility Patterns during the Middle Stone Age,” recently published in the Journal of Paleolithic Archaeology, reports some of the results of my investigations.

The Cave of El Aliya

The Mugharet el’Aliya, or the Cave of El Aliya, is situated on the Atlantic coast of northern Morocco, near the city of Tangier. This cave was excavated in the late 1930s and the 1940s and produced highly unique MSA lithic assemblages.

Layer 6 in particular produced numerous finely crafted, bifacially flaked points, commonly known as bifacial foliates. Bifacial foliates are stone tools that have been worked on both sides, meaning flakes have been removed from both surfaces of the stone to shape it into a pointed form.

Bifacial points make up almost one-fifth of all the retouched tools from this layer. This proportion is unlike any other seen among MSA sites in the Maghreb. However, no studies aimed at understanding the behavioral patterns that produced this stone tool evidence had been conducted in the past. 

My article presents the results of a comparative analysis of the lithic evidence from Layer 6 of El Aliya and that from the MSA layers of the Moroccan cave sites of Bizmoune, Rhafas, and Dar es Soltan 1. Specifically, I compared four aspects of the selected stone tool collections:

• Assemblage composition – What are the types of tools present at each site and how diverse are they?
• Fragmentation of reduction sequences – Were the stone tools generally made on-site?
• Patterns of lithic raw material provisioning – How varied are the rocks used for tool making, and how far were they procured from?
• Artifact reduction rates – How worn down are the stone tools?

Stone tools, site use, and group mobility

My results indicate that Layer 6 of El Aliya is different from the other sites in many ways. Not only does it contain strikingly more bifacial foliates than all other sites, but also other types of pointed tools such as Mousterian points. Some of these pointed artifacts show damage potentially resulting from their use as part of hunting equipment. The evidence indicates that most of the retouched tools were not made on-site. Rather, they were rather produced at other locations and brought inside the cave as finished implements. Lastly, the tools from this site are significantly more worn down than those from all other sites. This was unexpected, as almost all tools from El Aliya were made of locally available flint. Flint is a high-quality stone that could be obtained within just a few kilometers of the cave. 

Previous research showed that Layer 6 of El Aliya contained a large collection of animal remains. These remains were accumulated by humans, reflecting the intense and specialized hunting of gazelles. The combination of faunal and lithic evidence suggests that during the MSA, the Cave of El Aliya was used by highly mobile foragers. During brief forays, these foragers conducted a narrow set of activities mainly associated with processing the animal prey they hunted in the surrounding landscape.  

Behavioral flexibility among early modern humans in North Africa

These findings suggest that the MSA hunter-gatherers of Northwest Africa developed strategies of mobility, site function, and exploitation of animal resources that were more diverse than previously thought. Patterns of high mobility and brief occupations during the MSA have been recognized at other caves on the Atlantic littoral of Morocco, but they tend to be associated with a wider variety of activities and exploited animal resources.

Also, the MSA levels of El Aliya seem to be younger than those at the other caves on the Atlantic coast of Morocco. Layer 6 was probably deposited between 60 thousand and 35 thousand years ago, during a period known as Marine Isotope Stage 3, when the sea level was lower and the coast was farther from the site compared to its current location. The differences in economic behaviors of the MSA foragers of El Aliya may reflect the adaptation of human subsistence strategies to changing landscapes over time. 

This research project will be expanded through continued collaborative work with Moroccan colleagues, and I will add data from more geographically and temporally diverse sites to better understand the variability of behaviors of the MSA foraging societies of North Africa and the degree of their adaptability to the landscapes they occupied.