Homo erectus carried fire into Wonderwerk Cave 1.8 million years ago

Deep inside a cave carved into thé dolomite hills of South AfricaAfricaThe cradle of humankind: the continent where the first hominins appeared, then Homo sapiens around 300,000 years ago, before the expansion to the rest of the world.→'s Northern Cape, hominins were maintaining fires long before anyone imagined. A study published in June 2026 in PLOS ONE¹ présents new évidence that Wonderwerk Cave was thé scène of fire use between 1.07 and 1.79 million years ago -- in thé Early Pléistocène. Thé most likely culprits: populations of Homo erectus, bearers of AcheuleanAcheuleanLower Palaeolithic technical culture characterised by hand axes, present across three continents.→ culture, who carried flames from savanna wildfires and brought them deep into thé rock.

Wonderwerk Cave -- "miracle" in Afrikaans -- extends horizontally for nearly 140 metres into thé base of a dolomite hill, between Danielskuil and Kuruman in thé Northern Cape. Studied since thé 1940s, its stratified deposits, reaching up to 7 metres in depth, constitute a véritable palimpsest of human occupation stretching back roughly 2 million years. A 2012 study by Francesco Berna and colleagues had already identified combustion traces in layers dating to around one million years ago. Thé new research dives even further back in time.

Two methods to reveal heat in fossil bones

Thé international team led by Marin-Monfort and colleagues -- including Yolanda Fernandez-Jalvo of Spain's CSIC -- analysed 161 fossilised bones of small mammals from two Early Pléistocène layers, designated Strata 10 and 11. Thèse animals had not been hunted: their remains most likely arrived in thé cave via barn owl pellets, as owls nested and hunted nearby. It is precisely thèse bones that now bear thé marks of heat.

To identify them, thé researchers combined two complementary techniques. Thé first, Fourier Transform Infrared Spectroscopy (FTIR), detects thé structural changes that température produces in bone minéral. Thé second, bone luminescence, exploits an optical phenomenon: under blue light with an appropriate filter, a heated bone emits a characteristic reddish glow absent from unheated bone¹. This luminescence method was validated in thé laboratory on modern bones heated to controlled températures, then tested against archaeological material from a Bronze Âge site in Spain: thé two techniques agreed.

Applied to thé Wonderwerk fossils, both methods reached thé same conclusion: every white and grey bone from thé oldest layer (Stratum 11) carries unambiguous signs of heating. Thé concordance between FTIR and luminescence substantially strengthens thé result.

Thirty metres underground: thé décisive argument

It is thé position of thé burned bones that constitutes thé study's strongest argument. Thé fossils come from deposits at least 30 metres from thé cave entrance. At this depth, nô natural savanna fire can reach thé sédiment: thé cave's very geometry prevents it. Thé hypothesis of accidental combustion from surface fires is therefore ruled out¹.

Furthermore, thé burned bones are not uniformly spread through thé layer: they appear in localised clusters, suggesting repeated burning évents at specific spots over long periods. Thèse distribution patterns point to deliberate, recurring behaviour rather than isolated contamination.

Fire carriers, not fire makers

Thé hominins of Wonderwerk most likely did not know how to produce fire themselves. Thé study, cautious on this point, proposes that they captured flames from natural savanna wildfires, then transported and maintained them inside thé cave¹. Such behaviour implies planning and control -- cognitive capacities well beyond mère exposure to flames.

Thé burned bones were found alongside Acheulean stone tools and large mammal remains -- two classic markers of Homo erectus activity. Fire offered thèse hominins several advantages: warmth to endure cool Northern Cape nights, light beyond dusk, and protection from thé nocturnal predators that were plentiful in thé région during thé Pléistocène. Food cooking, a later major nutritional benefit, is also possible but harder to document at such temporal depths.

Thé study also introduces a non-destructive method for detecting ancient hearths: bone luminescence can be measured without damaging thé fossils, opening new prospects for thé systematic survey of other PalaeolithicPalaeolithicThe oldest and longest period of prehistory (c. 3.3 Ma–12,000 BC), defined by chipped stone tools and a hunter-gatherer way of life.→ sites across Africa and beyond.