When the desert does not preserve: a study reveals why the bones of the first Andean hunters disappear

A research team led by IPHES-CERCA has demonstrated that the absence of bone remains at many Late Pleistocene sites in the Andes does not necessarily indicate a lack of human activity or the exploitation of animal resources. On the contrary, even in hyper-arid environments such as the Atacama Desert, bones can degrade to the point of completely disappearing as a result of extremely active microscopic processes.

This is the main conclusion of a study recently published in the journal Environmental Archaeology, which provides new insights into one of the major enigmas of Andean archaeology: why many high-altitude sites, rich in lithic tools associated with hunting, preserve little or no faunal remains

The research was led by Sebastián Yrarrázaval, with the participation of Isabel Cáceres and Boris Santander, researchers at IPHES-CERCA, as well as specialists from several institutions in Chile. The study focuses on the Puna of Atacama, a region located at more than 3,000 metres above sea level, where numerous hunter-gatherer settlements dating between 12,000 and 10,000 years ago are known. These sites are characterised by an abundance of projectile points and tools related to animal processing, but by an almost testimonial presence of bone remains.

The myth of the desert as a space of “perfect” preservation

Hyper-arid deserts have traditionally been considered ideal environments for the preservation of organic materials. However, the results of this study challenge this widely accepted assumption. Using an actualistic approach, the team analysed modern bones of camelids and other animals from two geographically close but ecologically contrasting environments: the hypersaline salt flats of Punta Negra and the high-altitude ravine systems of Llullaillaco National Park.

Through histological analyses—that is, the study of the microscopic structure of bone tissue—the researchers identified processes of bacterial bioerosion, microfracturing associated with desiccation, and alterations caused by salt crystallisation. Together, these processes can progressively destabilise bone until it disappears entirely from the archaeological record.

“Our results show that extreme aridity does not guarantee good bone preservation,” explains Sebastián Yrarrázaval, lead author of the study. “In certain contexts, especially saline environments, diagenetic processes can be so intense that they ultimately destroy the faunal record completely.”

Two landscapes, two taphonomic pathways

The study reveals clear differences between the two environments analysed. In high-altitude ravines, where permanent watercourses and greater biological activity are present, bones show better microscopic preservation. However, they are also more likely to be dispersed due to the action of scavengers and other natural processes.

In contrast, in the Punta Negra salt flats—characterised by intense solar radiation, large thermal fluctuations and hypersaline soils—bones are subjected to a particularly destructive combination of early bacterial degradation and subsequent fracturing. This sequence can lead to the total disappearance of bone evidence at an archaeological scale.

According to the authors, this mechanism may explain why many surface sites in the Puna of Atacama, despite clearly evidencing hunting activities, preserve virtually no animal remains.

Rethinking the absence of bones in the archaeological record

These findings have direct implications for the interpretation of the earliest human settlements in the Andean highlands and in deserts worldwide. The study warns that the absence of bone remains cannot be automatically interpreted as an absence of animal exploitation; instead, it is essential to consider the taphonomic and diagenetic processes that may have eliminated this evidence.

“This work demonstrates the importance of integrating taphonomic and histological studies to understand what has disappeared from the archaeological record and why,” notes Isabel Cáceres, researcher at IPHES-CERCA and co-author of the article. “Only then can we reconstruct the subsistence strategies of early human populations with greater accuracy.”

The study represents one of the first systematic approaches to histotaphonomy in high-altitude deserts and opens the door to future experimental research aimed at better understanding how climate, microorganisms and physical processes interact in the destruction of the bone record. 

Bibliographic reference

Yrarrázaval, S., Cartajena, I., Santander, B., Huerta, V., De Souza, P., & Cáceres, I. (2025). Actualistic Taphonomy at the Puna of Atacama: Microregional Histotaphonomic Comparisons in Highland Andean Basins (24,5°S). Environmental Archaeology, 1–19.

https://doi.org/10.1080/14614103.2025.2607176