The invention of fire was one of the big developments in our evolutionary history. I'm certainly grateful for it every time we crack out the barbeque. A good pulled pork is the pinnacle of our evolution. However, identifying when we began the journey to these tasty treats is difficult. Fire can occur naturally, and even be exploited when it does so. For instance, chimps will follow behind fires, taking advantage of all the food it left behind.
Figuring out when our ancestors switched from this chimp-like exploitation is difficult. The evidence will be similar on both sides of the divide. Namely, a bunch of hominin stuff looking burnt. Thus, there's about a million years margin of error between when we know they encountered fire and when we know they were in full control. However, new research from Africa is shrinking this; pushing the possible origin of controlled fire use back to ~1.5 million years ago. That's more than half a million years earlier than the next oldest confirmed evidence.
Previous record holder
It's times like this I realise how long I've been doing this website. It turns out I actually wrote about the previous "oldest" case of fire back when it was fresh news. The site in question is Wonderwerk Cave, South Africa, and dated to close to a million years ago. It contained several traces of burnt material, indicating repeated fires within the cave.
The fact that the fires were repeated, and in a place that normally doesn't burn, indicates that hominins were responsible. For further confirmation, several hominin artefacts were also found at the site. The date and timing of this sites suggest the likely culprit was Homo erectus, although no fossils were recovered to confirm this.
Crucially, the fact there was repeated burning in the cave indicates they had good control over the fires. It's easy to imagine an early human stealing a burning branch from a forest fire and dragging it home. But for that to happen multiple times? Suddenly it starts to look like that early human actually had some control over it. Further evidence of this comes from the fact sections of the cave were heated to high temperatures, indicating they could keep the fire burning intensely and for a long time.
Between Wonderwerk and now our relationship with fire got closer and closer. We start seeing camps organised around hearths. There are tools heat-treated to make them stronger. And eventually, I start to make that tasty pulled pork.
Koobi Fora Fire
The "new" earlier evidence of fire is old. Both in the sense that it's older than Wonderwerk and it's actually quite an old discovery. The site in question is called Koobi Fora, in Kenya, and was first discovered in the 60s. Since then fossils have been found stretching back more than 4 million years. But the part that interests us is a section with the memorable name of FxJj20. It dates to ~1.5 million years ago and contains evidence of fire.
Like the rest of Koobi Fora, this isn't particularly new either. Evidence of burning was found quickly after the sites first discovery and published in the early 70s. The site was found to contain heated sediments, bone, and stone. The burnt stuff even seemed to be clustered together, kind of like a hearth. Despite this many have remained skeptical, given the fact there's no other solid evidence of fire until Wonderwerk cave. If they really did have control over it, why did they stop burning stuff for so long? Even when the spread to chilly old Europe, they didn't bother trying to heat themselves up.
The new research expands out the original excavation and thoroughly documents the entire thing. Patterns immediately become clearer. Burnt objects are gathered around hearths. Burnt lithics are missing from the hearth locale, indicating people having some control over what goes into the fire. Unburnt stuff made by hominins is close to the hearths, but a bit further away than the burnt stuff. Activity, burning or otherwise, was clearly congregated around the fire.
This reinforcement of the existence of hearths at Koobi Fora shows that Homo erectus was congregating around and exploiting fire at this locale.
Did they start the fire?
Despite the reinforcement of the hearth evidence, there are still some questions about this site. Notably, it doesn't change the fact that there are no other solid contemporary sites. Why did Homo erectus forget about burning for half a million years? It could be that hearths are surprisingly hard to find. Much of the burnt material is very small, requiring a high-tech approach not available when many of these sites were first found. Might the evidence have simply been lost?
Another idea I'm a bit more partial to is that the hominins hadn't mastered the creation of fire just yet. They could exploit and curate it, keeping it burning for a long time. Yet they couldn't ignite it, limiting the frequency of fires. Perhaps the increase of burning that happened after Wonderwerk represents the actual "invention" of fire after all.
Given they had yet to domesticate the pig and invent barbeque sauce, perhaps they had no real motivation to do so yet.
References
Berna F, Goldberg P, Horwitz LK, Brink J, Holt S, Bamford M, & Chazan M (2012). Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. Proceedings of the National Academy of Sciences of the United States of America PMID: 22474
Gowlett, J.A., 2016. The discovery of fire by humans: a long and convoluted process. Phil. Trans. R. Soc. B, 371(1696), p.20150164.
Hlubik, S., Berna, F., Feibel, C., Braun, D. and Harris, J.W., 2017. Researching the nature of fire at 1.5 mya on the site of FxJj20 AB, Koobi Fora, Kenya, using high-resolution spatial analysis and FTIR spectrometry. Current Anthropology, 58(S16), pp.S000-S000.
