Fire and Human Evolution
Despite the field’s general agreement that pyrotechnology had a significant impact on the cultural evolution of humankind, our understanding of the origins and development of fire use and its role in humankind’s cultural evolution is very limited, blurred by strong disagreements over its chronology and its impact on socio-cultural aspects of human life and environments.
- Wil Roebroeks
The use of fire is a defining characteristic of the human lineage, with pyrotechnology being one of the most powerful tools developed during human evolution. Fire control brought many advantages: it afforded humans protection against predators and cold, and substantially increased the range of edible foods and the energy that could be extracted from them through cooking. Fire extended the length of the day and impacted the character of social interactions, as is well-documented through ethnographic studies of the contents of fireside conversations, which include the sharing of stories and myths. Fire also came with costs, as hominins had to collect fuel to be brought to a central place, and individuals had to work together to profit from fire. Fire gave humans a means to increase the productivity of their habitats by burning, over time transforming their environments into cultural landscapes and impacting “System Earth” long before the Anthropocene.
Despite the field’s general agreement that pyrotechnology had a significant impact on the cultural evolution of humankind, our understanding of the origins and development of fire use and its role in humankind’s cultural evolution is very limited, blurred by strong disagreements over its chronology and its impact on socio-cultural aspects of human life and environments. In the last decade, Leiden archaeologists of the Human Origins group have addressed these issues in a variety of ways, in research that is still ongoing.
Ancient fire use
A 2011 PNAS study concluded that fire became a fixed part of the human technological repertoire relatively recently, “only” about 400,000 years ago, i.e. more than 1-1.5 million years later than usually acknowledged. This would imply that early humans moved into Eurasia almost one million years before starting to use fire on a regular, archaeologically visible, basis. However, the archaeological record is notoriously fragmentary, fire use by mobile foragers leaves few traces, and those of much earlier fire use may simply have not been preserved. To address this, Leiden archaeologists initiated a series of laboratory experiments designed to study the taphonomic history of heated materials (what happens to heated bone and stone once they become buried in sediments) to identify the best scientific methods to reconstruct former heating conditions.
These studies by Femke Reidsma et al. hold the promise to be turned into a “toolkit” that can be used at archaeological sites of all ages, to establish the character of fire traces in great detail (natural or anthropogenic?), and to identify the former functions of fireplaces, e.g. the fuels used and foods prepared therein. A proof of concept of this approach was recently published in a multidisciplinary study of 40,000 to 20,000 years old hearths from the Abri Pataud rock shelter at Les Eyzies (France), which pioneered the retrieval of ancient DNA from sediments in this context. This developing toolkit forms an essential bridge between the archaeological record and inferences about how fire use shaped human cultural behaviour.
We have also used ancient genomes to track human adaptations to fire use, to obtain “archaeology-free” data about our relationship with fire. Teaming up with Jac Aarts and other scientists from Wageningen University, we showed that, surprisingly, Neanderthals were better at dealing with the toxic products of smoke than modern humans are, opening up a whole new line of research into the possible implications of fire use for human health. We also conducted ethnohistorical studies of cultural and biological “fire-free” ways of staying warm in seasonal environments.
Ancient fire making
In addition, using fire does not entail its production: wildfires provide a source of burnt foods or flames, and a flame can be maintained for long periods without the use of fire-starting tools. Changes in fire-related skills and technology must have altered human interactions with fire dramatically. The team invested considerably in studying how fire may have been produced in the deep past, again in a multi-proxy approach (that resulted in a 2018 study providing the first evidence of fire production by Neanderthals.
Moving beyond the scale of campsites, Leiden archaeologists also put on the map the worldwide use of fire in shaping cultural landscapes by hunter-gatherers (“fire-stick farming”), in a systematic review of ethnographic sources that resulted in a Current Anthropology paper and an open-access database. That study is very topical at the moment because of the problematic increase in fires e.g. in Australia and the Americas, and debates on the role of indigenous populations in environmental restoration. It was steered by the team’s long-term fieldwork at Neumark-Nord (Germany), where abundant traces of fire use by Neanderthals were recovered from 125,000-year-old deposits, with a strikingly open vegetation signature in the pollen record during the 2,000 years of hunter-gatherer presence there. We have very recently completed an extensive study of these Neumark-Nord data, concluding that the area provides the earliest convincing evidence of hominins moving about in a landscape which they substantially shaped themselves, by fire use: i.e. a cultural landscape, 125,000 years old.
In a challenging synthesis of all these “ancient fire” building blocks, in 2021 team members published the hypothesis that the regular use of fire 400,000 years ago, widespread over the Old World, signals the presence of a modern-human like capacity for cultural diffusion of skills, 100,000s of years earlier than commonly acknowledged and cross-cutting several hominin populations. Large-scale cultural diffusion is an important, distinctive characteristic, which together with adaptive or inherent value, regional traditions, and the accumulation of elements, or “ratcheting”, makes modern human culture stand out from related behaviours in other species.
This long-running project has received funding from various sources, including the Netherlands Organization for Scientific Research (NWO), the Royal Academy for Arts and Sciences (KNAW) and the Stichting Nederlands Museum voor Anthropologie en Praehistorie (SNMAP).