Fire use by hominins: an example of rapid cultural evolution?

July 26, 2021 • 9:15 am

Yesterday we discussed the possibility of cultural evolution (dissemination of a behavior or skill through imitation and learning) in cockatoos, which attracted a lot of attention, probably because of its parallel with human cultural evolution. (The cockatoos seem to have learned to open garbage bins by watching each other.) And in our species there are a gazillion examples, especially since transportation allowed innovations to be spread quickly and widely. You can think of lots of cases: blue jeans, cuisines from other places, music, and, earlier than that, printing, the wheel (some cultures never got it) and even religion.

The new paper in Proc. Nat. Acad. Sci. below, however, suggests what may have been the very first behavior that spread though species of Homo (not only H. sapiens, but perhaps Neanderthals, which some consider a different species) through movement of individuals: the use of fire.  Click on the screenshot to read the article (free) below, or get the pdf here. The reference is at the bottom.

Fire, of course, has many uses: besides cooking meat and tubers, it can be used to harden wood to make spear points, change the quality of stone to make it easier to flake, and to keep yourself warm. Other uses are given in the Wikipedia article “Control of fire by early humans.”

The MacDonald et al. paper collects evidence of fire use from species of Homo, concluding that it got started about 400,000 to 350,000 years ago and then spread rapidly throughout the species. The rapidity of spread then led them to propose what kind of social structure was present in humans at that time.  This contradicts speculations H. erectus controlled the use of fire about 1.5 million years ago; the authors find that evidence unconvincing.

The problem is to distinguish anthropogenic (“human caused”) fire from natural wildfires. But there are ways of doing this, as the article summarizes. Hearths and charred animal bones are one way. Here’s another bit of evidence: a fire-hardened wooden spear from, coincidentally, about 380,000-400,000 years old, part of a group of artifacts found in Germany:

I can’t evaluate the quality of the evidence, but the authors summarize a lot of data to conclude that regular fire use began about 400,000 years ago, and spread quickly throughout the Old World, with evidence coming from Portugal, Spain, France, Israel, and Morocco. Two quotes:

. . . a review by Roebroeks and Villa identified a clear pattern for Europe: there the record strongly suggests that anthropogenic fire use was very rare to nonexistent during the first half of the Middle Pleistocene, as exemplified by the absence—bar a few dispersed charcoal particles—of fire proxies in deeply stratified archaeological karstic sequences, such as the Atapuerca site complex in Spain or the Caune de l’Arago at Tautavel (France), as well as from such prolific open-air sites as Boxgrove in the United Kingdom. In contrast, the record from 400 ka onward is characterized by an increasing number of sites with multiple fire proxies (e.g., charcoal, heated lithics, charred bone, heat-altered sediments) within a primary archaeological context.

. . . The spatiotemporal pattern of the appearance in the archaeological record of an innovation provides evidence relevant for identifying how the innovation came to be widely distributed: that is, through independent innovation, demic processes, cultural diffusion, or genetic processes. The fact that regular fire use appeared relatively quickly across the Old World and in different hominin subpopulations strongly suggests that the behavior diffused or spread from a point of origin rather than that it was repeatedly and independently invented.

Since fire appeared in both warm and cold places around the same time, the authors suggest that its inception was not correlated with “environmental pressures” (e.g., cold). And because the spread was so rapid, the authors claim, correctly, that the spread throughout the Old World was very unlikely to have been caused by the diffusion of genes producing the tendency to create fire, which would spread only very slowly. Likewise, the near-simultaneity makes it seems unlikely that the use of fire was invented independently by several groups.

If fire use did spread through imitation and learning, then, what does that say about the social structure of early humans? If we were divided up into groups of xenophobic hunter-gatherers who didn’t interact, that would not facilitate the spread of fire. Why would a group give the skill to a competitor group? There are two alternatives.

The first, “demic diffusion,” is that a “deme” (a cohesive populations of hominins) spread rapidly, taking with it the fire use they invented. This seems unlikely given that the spread was more rapid than one could imagine a single population could migrate.

The alternative comprises groups that tolerated each other, and were at least somewhat friendly. As the authors suggest, there was a more “fluid social structure with multiple levels of clustering in social networks”. In other words, perhaps hominims were more interactive than we thought.

Well, we have no direct evidence for that, and it would be hard to come by. And I’ll let other physical anthropologists judge the “simultaneous spread” hypothesis. But I wanted to bring this up because the scenario is at least plausible, and it may be the first evidence for cultural evolution in our genus.

There’s one other trait they add in to the mix as another behavior that spread by cultural evolution: the “Levallois technology” for knapping stone (striking flakes off a stone like flint to make weapons and other implements). This, say the authors, can be learned only through “close and prolonged observation combined with active instruction.” Here’s the Levallois method, which involves producing a flint core in such a way that sharp flakes, useful for tools, can be easily struck off:

The authors posit that this technology also originated in one place, but about 100,000 years later than fire (and surely in a different place), and then spread rapidly among groups in a similar way: non-hostile group interactions in a multi-level social network.

I’ll close with the authors’ final paragraph, summarizing their views:

We hypothesize that around 400 ka, cultural processes supported change in technology across wide areas. This indicates, at a minimum, a degree of social tolerance for individuals from different groups, and suggests the less minimal but still plausible hypothesis that more intensive cooperative interactions within larger-scale networks were already in place, occasionally crossing the boundaries between what we usually infer to have been different biological populations within the wider hominin metapopulation. [JAC: I think they’re referring to movement between “modern H. sapiens and Neanderthals. After all, these groups did mate with each other] We conclude that the spatial and temporal pattern of the appearance of regular Middle Pleistocene fire use documented in the archaeological record signals more than the advent of an important tool in the hominin toolbox: the presence of cultural behavior more like that of humans today than of our great ape relatives. We suggest that long before the cultural florescence associated with the late MSA/Middle Pleistocene and to a greater extent LSA/Upper Paleolithic periods, hominins were beginning to develop the capacities for complexity, variability, and widespread diffusion of technology and behavior that we tend to associate only with H. sapiens.

__________________________

MacDonald, K., F. Scherjon, E. van Veen, K. Vaesen, and W. Roebroeks. 2021. Middle Pleistocene fire use: The first signal of widespread cultural diffusion in human evolution. Proceedings of the National Academy of Sciences 118:e2101108118.

24 thoughts on “Fire use by hominins: an example of rapid cultural evolution?

  1. It’s popular to consider hunter/gatherer groups as xenophobic, but 400,000 years ago there were not that many ancestors. Estimates range from 1 – 10 million 10,000 years ago, so probably even fewer way back then.

    My guess is that if one group encountered another when there was no competition for scarce resources they would party, exchange young men and/or women and perhaps pass on survival tips, like fire.

    1. Has anyone considered spying? One clan can steal technology from its enemies without having to befriend them.

  2. Fire, of course, has many uses: besides cooking meat and tubers, it can be used to harden wood to make spear points, change the quality of stone to make it easier to flake, and to keep yourself warm.

    Not to mention giving the world the 1968 chart-topping tune by Arthur Brown.

      1. Indeed they are. And, since his helmet was made of metal, heat from the flames was conducted to Mr. Brown’s head, causing him a good deal pain while performing.

        Such are the sacrifices one must sometimes make for the sake of one’s art. 🙂

  3. There is an interesting book by Mark Moffett called “The Human Swarm” that postulates hunter gathers had some kind of meta-clan structure composed of multiple hunter-gatherer bands who would share language/culture/religion (essentially social identity) but be dispersed, but might gather together for warfare against another clan. Humans definitely made some kind of leap up from bands of relatives which allows us to “ape” insect social structures, probably related to the development of language, religion, culture to provide group identity (in contrast to pheromones).

  4. Direct and unequivocal evidence of controlled use of fire by hominins is uncommon and difficult to discern in the archaeological record. Jack Harris (Archaeologist at Rutgers) published on burnt patches in Kenya, which are dated to more than 1.6 mya and are associated with stone tools. However, it is also possible that those burnt patches are simply remains of trees that burned in wildfires while tool-using hominins walked by later or before (I excavted some of those patches, I think they are burnt tree stumps). Richard Wrangham, a primatologist, argues that the relatively rapid brain expansion seen in early Homo beginning about 2 mya can ONLY have occurred because hominins were using fire to cook food (making more calories and nutrients available to a growing brain). He argues that such brain expansion is impossible on a raw diet typical of chimps and other primates, no matter what high calorie and high quality foods they consume. It is an interesting approach from a scientist who never picked up a trowel. Wrangham’s idea is compelling and testable, which is also nice (lots of experiments I can think of). Wrangham puts controlled use of fire and cooking by hominins more than 1 my earlier than the earliest clear archaeological evidence for fire.

    1. It seems logical that early hominins encountered and used some form of fire which must have been
      commonly caused by lightning strikes. That the use of fire had a single origin seems
      counter intuitive to me.

      1. “The MacDonald et al. paper collects evidence of fire use from species of Homo, concluding that it got started about 400,000 to 350,000 years ago and then spread rapidly throughout the species.”

        My point is that there are some archaeologists and anthropologists who argue (using very different lines of evidence) that the controlled use of fire by hominins was well established and widespread much earlier.

    2. There was probably a considerable grey area between “understanding fire as a useful if dangerous tool” (a category earlier invented by a chimpanzee-hominid common ancestor who got a splinter from the stick she was using to grub up tubers) and “I can go to a new place and make a fire in a matter of an hour or so” – which one could consider approximating “mastery”.
      (Anatomically Modern Humans have a subspecies called “fireman” dedicated to regaining control of uncontrolled fire ; it can be challenged if AMHs actually have full “control” of fire today.)
      Whether that “grey area can accommodate a 1-1.5 Myr of development between the 1.5-2.0 Myr earliest claims of human-associated fire sites, and the ~0.4 Myr figure these authors propose … is a fair question. But it’s also unlikely that the “fire” meme (sense : Dawkins) went from “using accidental finds” to “making at will” overnight.
      Thinking back to the seasonality of climate in much of East Africa, there could easily have been a long period when hominids could use accidental fires during (and for some months after) the dry season, but eventually lose a particular instance of “fire” to the following rainy season. Which would allow a considerable period to develop uses for fire, and develop techniques for moving fire, before successfully developing techniques for starting fires on demand.

      To spread a meme (sense : Dawkins) at 0.4 Myr BP, the meme is going to be travelling mostly across terrain with some significant degree of indigenous population of humanoids, who even if they’re not close relatives (say, Denisovans meeting Neanderthals) are both threatening (“they have spears and hand axes too!”) and/or tempting (“I don’t like the look of yours, Ug!”) So it seems likely that brain-brain transmission of memes would be faster than the movement of feet (and genes). Potentially, the distribution of genes across Asia and N Africa could illuminate both patterns and rates of movement of genes – though archaeology would need a lot more, better preserved, in-context DNA to have much confidence in such models.

      How fast does (did) news travel across the Amazonian rain forest between “un-contacted” tribes (or, in the past, across North America with the news of these murderous thieving pale-faces with the serious weaponry). Given that people like MacKenzie could get from Hudson Bay to the Rockies and back again in a couple of seasons, and was moving into an environment where the concept of “trading” was an established thing, such movement of information could be so fast as to be archaeologically instantaneous. The archaeological record has abundant examples of desirable materials (e.g, obsidian for tool making, or part-prepared stone axe blanks of particularly good stone) travelling hundreds of miles in – one assumes – one trader’s back pack (travois?), then we can infer that useful skills like fire would also travel pretty damned quickly.
      (At the very edges of hominid existence, such as entering Europe and NE Eurasia in the interstadials of the Ice Age, or spending enough time on boats in Indonesia to end up in the Phillipenes and Australia, “demic diffusion” would have been slowed by the need to develop new technologies.)

      1. The 1981 film “Quest for Fire” deals with a tribe of Neanderthals who use fire [presumably scavenged from a forest fire] but do not know how to make it. When they lose their fire, three men from the tribe go on a quest to find more and bring it back.

        Scientists dismissed the film as filled with anachronisms [e.g. apelike hominids living in the same period as people living in villages], but I enjoyed it as a piece of entertainment. The scene where a Neanderthal looks on in awe as another human creates fire is great.

        1. Hmm, haven’t heard of that one.
          It has a faint campanology to it – I may have read a (SF) short story on a similar topic.

    3. “Richard Wrangham, a primatologist, argues that the relatively rapid brain expansion seen in early Homo beginning about 2 mya can ONLY have occurred because hominins were using fire to cook food (making more calories and nutrients available to a growing brain).”

      I’ve heard that hypothesis before. I don’t know how well supported it is or what the general consensus regarding it is among relevant experts, but this brought to mind an interesting article I came across last year about some research that suggests another possible reason for rapid brain expansion in early Homo.

      Scientists Make Bigger Monkey Brains With The Help Of A Human Gene

      Long story short, there is a human gene (actually occurs in Neanderthal’s & Denisovan’s as well) that causes a significant increase in the size and folding of the neocortex compared to our close relatives. This was demonstrated by inserting the gene in fetal marmosets per this paper, Human-specific ARHGAP11B increases size and folding of primate neocortex in the fetal marmoset.

      Related research per this paper, A single splice site mutation in human-specific ARHGAP11B causes basal progenitor amplification, shows that this difference between the human variant of this gene and the variant in our close ancestors is due to a mere single point mutation. Also interesting is that it looks like this mutation occurred relatively recently. From the paper,

      “ARHGAP11B is the first, and hitherto only, human-specific protein-encoding gene that was shown to increase BP generation and proliferation (23). It arose on the human evolutionary lineage ~1 million years after divergence from the chimpanzee lineage, existed in Neanderthals and Denisovans, and is found in all present-day humans (23–25).”

  5. In 2010, Richard Wrangham wrote the book “Catching Fire: How Cooking Made Us Human” about how cooking help us acquire a big brain. I found the book interesting but do not have the background to evaluate the science. It seems like it complements this study.

  6. One significant advantage (re: selection) for control of fire: fire softens muscle meat, making the consumption of the entire animal much easier, as opposed to only eating soft materials such as marrow, brain, gland and organ meat.

    Also, if you watch videos of current hunter cultures, you see they treasure animal fat the highest; and they hold it up to the fire prior to eating it. Fire renders it more edible than raw.

    I might well be that ‘seeing’ this advantage was an instant adaptation, tribe to tribe, but it also might mean that fire-controlling populations could overwhelm non.

    1. Wrangham cites studies where modern humans went on a totally raw diet. They all lost weight (without trying or wanting to), even when consuming abundant calorie-dense fat-dense raw foods like avocado, nuts, and raisins and even raw meat and animal fat. Fire makes calories significantly more digestible and easily absorbed. Cooking also neutralizes many plant toxins that inhibit absorption of nutrients. He argues and is gathering data from metabolism studies, that humans could not have undergone the significant brain enlargement without regular cooking. And, could not have maintained the active cognitive levels seen with development of new technology and invading new environments without mastery of fire.

      Australopiths never ventured out of Africa, although there were not really any geographic barriers (many other African mammals migrated out). This suggests they lacked the ability to adapt to new and unfamiliar environments. Homo did that easily, Wrangham suggest, by taking fire with them. The fact that there is virtually no direct archeological evidence for controlled use of fire more than 0.5 mya is no problem — as such evidence is not likely to persist for long. He argues we became human because of our mastery of fire.

      ANother important fact is that Homo experienced significant brain enlargement beginning 2my ago, and also there is significant reduction of the size of jaws and teeth. This suggests a switch to a softer, yet highly nutritious diet, a cooked diet.

      To my knowledge, there are no studies that attempt to measure edible biomass available on a landscape following a bushfire. That would be a nice little project. Chimps and Gorillas both prefer cooked food over raw, not matter what the food. Baboons and other monkeys often forage in areas where fire has previously swept through (I’ve seen this personally). I’m not aware they show any preference for such regions, although it seems likely they encounter some burnt edible things. Many predators will snare prey fleeing from fire, but that prey remains uncooked.

      Wrangham’s theory is largely (not entirely) circumstantial. But, I find it very compelling. Archaeologists don’t spend much time reading primatology. Maybe they should, especially those who focus on early hominin behavior.

      1. Echoing your comment.

        2MYa bipedalism and larger brains … but cooking food only 400,000 years ago? I don’t think so.

      2. Loved that book. Of course, as a chef, I’m biased, willing to believe that “it all began with cooking.”

  7. Thanks for this interesting post. I didn’t read the entire paper, but I’m sure they mentioned that cooking would also kill parasites. I’ve often wondered if most early humans had worms. Gross thought, I know.

    Also, I didn’t know that fire hardened wood. Does it harden all wood or just specific types of wood? And why does it harden? Something to do with the sap?

  8. A few thoughts. If tool making goes back 3 million years it is not outside the realm of probablity that sparks flying of chipped stones for tool making may have made them curious to other uses… that is, if early hominin started bashing flint together they may have stumbled upon fire making.
    It amuses me because some of ‘modern’ human innovation has been discovered this way,

  9. That early Homo would have been divided into small, mutually hostile, xenophobic groups incapable of communicating with one another seems to be a strawman null hypothesis against which to herald previously lacking evidence of social interaction. The following picture, showing an artist’s conception of two bands of Homo erectus meeting up, with the caption saying, in part, “the exchange of mates between different bands might well have been a common practice”, is from Early Man by F. Clark Howell in the Life Nature Library (1968). That’s about as mainstream/consensus as you can get.
    Homo erectus, fide F.C. Howell (1968).

    GCM

  10. Well this is another interesting discussion. The first thing I noticed was the bit about the technology spreading “relatively quickly”. Relative being the most important term. I think modern people tend to underestimate the ability of people walking to cover large distances. Even if such a technology was not actively traded or shared, it would probably spread when bands sporadically camped together or exchanged mates. A captive might even spread the technique to a new band.
    Considering the estimated area covered by each band, it would not take very many such interactions to spread the technique across a continent. In the scale of time we are discussing, it would seem almost instantaneous.

    On a related note, last week I was looking at the remains of a fire that some old timers left on our place. Really a few feet cleared of rocks, with a hint of ash. The only dating evidence I found was some tin cans, which were of the hand-soldered type, with lapped seam, which puts it in the middle of the 19th century. But there was very little remaining of the actual fire itself, as it was out in the open, in a place subject to extremes of weather, and very likely the old timers just camped for a night or two, then moved on. If not for the rusted tins, I probably would never have seen it. I always look for bones, as we had an infamous cannibal go through the area in that era.
    But really, unless it is a large fire, maintained over a long period, a fire in a site that was used repeatedly, or perhaps one in a place shielded from the elements, the remnants are pretty ephemeral.
    I do plan to take a trowel next time, and see what a little section looks like, as far as an ash layer.

  11. Mankind would of course never have gotten to this point without taming fire. But in two generations we’re well under way to undo that: “Make a fire in the fireplace?? OMG! I’d burn the house down!”

  12. “We hypothesize that around 400 ka…. infer to have been different biological populations within the wider hominin metapopulation. [JAC: I think they’re referring to movement between modern H. sapiens and Neanderthals. After all, these groups did mate with each other]”

    Sure, but I’m worried your timeline might be a bit wonky here. At “400 ka” not only were there no H. sapiens in Europe, but by any recognized metric H. sapiens didn’t even exist as a species yet.

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