# Diamonds in the rough - reconsidering the scientific and heritage value of heat-altered stones in prehistoric archaeology through a systematic literature review

## TL;DR

This paper reviews heat-altered stones from prehistoric sites to understand their role in ancient cooking and cultural practices.

## Contribution

The study systematically reviews literature on heat-altered stones, emphasizing their underappreciated value in understanding prehistoric human activities.

## Key findings

- Heat-altered stones date back to the Pleistocene and were used for culinary and non-culinary purposes.
- There is a significant lack of research on HAS from Africa, Oceania, Asia, and South America.
- HAS provide insights into ancient foodways and cultural heritage but remain under-studied.

## Abstract

Heat-altered stones (HAS) are commonly reported in prehistoric sites across several continents, yet they continue to be generally overlooked and systematic studies on them are scarce.

We performed a systematic literature review which consisted of searching journal articles, book chapters and books published in English, in Scopus and Web of Science. We collected information on their geographic distribution, chronology, composition, technological aspects and subsistence contexts from 73 records. Our aims were to assess the challenges and opportunities of analysing HAS, while highlighting that this class of artefacts is still largely an untapped source of information on prehistoric human activities.

HAS have been documented since the Pleistocene, attesting that culinary and non-culinary activities using heating stones emerged among foraging groups subsisting on hunting, fishing and gathering. The high frequency of HAS during the middle and late Holocene testifies to the continuation of some practices over long time periods, amid the emergence of new food systems, and the introduction of new resources and technologies, such as domesticated plants and animals, and ceramic containers. A considerable lack of studies on HAS from Africa, Oceania, Asia, and South America was noted, all of which are key geographic areas for assessing the role of heating stones in human evolution, geographic dispersal, early cuisine and diet, and cultural transmission across the globe.

Our results highlight the persistent challenges archaeologists face in establishing fundamental definitions and diagnostic criteria for identifying HAS, while emphasizing the importance of HAS as essential elements for studying ancient foodways and cultural heritage. We call on archaeologists and cultural heritage managers to reconsider the heritage value of HAS and include them in specialised research agendas before significant knowledge of our past is lost.

This study examines heat-altered stones (HAS), namely rocks that were heated and used by past people and found abundantly at archaeological sites. These stones offer valuable insights into the lifeways of past societies, including their cooking practices, diet, and use of fireplaces. HAS have been recovered in sites dating back to the Pleistocene, suggesting that even before the advent of farming and herding, people were heating stones for cooking and other activities. HAS continued to be used for thousands of years, evolving alongside the adoption of new tools and food systems. Although archaeologists have often found, recorded, and sometimes collected these stones, in-depth studies of HAS remain rare. Here we compiled existing knowledge on HAS, exploring their geographic and chronological origins, their uses, and how scholars have analysed them. Much remains unknown, especially concerning HAS from Africa, Oceania, Asia, and South America. Expanding research to include these regions can deepen our understanding of how ancient cultures used fire, prepared food, and shared these practices globally.