Late Mid-Pleistocene hominin fire control inferred from sooty speleothem analysis

The origin of fire control is considered a major turning point in human evolution and remains a highly debated albeit central subject in archaeology. Studying paleo-fires is challenging because of taphonomic phenomena that alter combustion structures and hinder the identification of the oldest hearths. Moreover, hearths do not record all fire events and do not provide a chronological record of fire. In contrast, speleothems, carbonated cave deposits, can preserve evidence of ancient fires, including soot traces, and these features can be dated directly using radiometric methods. Orgnac 3, an important archaeological sequence in Western Europe, provides a case study on the origins of habitual fire use in this region during the transition between the Lower and Middle Paleolithic. This paper presents the first documented record of over 20 fire events at this ancient site. The habitual use of fire by Mid-Pleistocene hominins at the site is well documented within sooty speleothems, as opposed to relying on scattered and rare traces. The soot deposit sequence at Orgnac 3 is the strongest and best-documented evidence of repeated fire use at the site to date. The robust fire-use chronology is established using stratigraphic U-Th dating of the speleothem. The soot record at Orgnac 3, testifying to fire events during both dry and wet periods, supports the hypothesis that Mid-Pleistocene hominins could control fire around 270,000 years ago in the Rhone Valley, with the possible ability to light it, or at least maintain it over a long term.