Hobaiter and Dominy turn the campfire theory of speech into six testable predictions
A Proc R Soc B paper argues that fire added as much as four hours to the day, and that fireside storytelling pushed human communication past the ape repertoire. The part worth watching is that a lab can check most of it.
The Scientist · Science desk
What happened
- A Proceedings of the Royal Society paper by Catherine Hobaiter of St Andrews and Nathaniel Dominy of Dartmouth proposes that fireside storytelling was the catalyst that moved human communication past ape-like systems.
- Where earlier accounts treated stories as something people began telling once a proto-language existed, this one reverses the order and makes storytelling the pressure that built speech.
- Fire made the evening usable, and the authors argue its light is unusually well suited to it because firelight carries very little of the blue light that suppresses melatonin.
- Visual neurons can fire in time with flickering light, and the authors ask whether a shared fire therefore aligns the attention and behaviour of everyone sitting around it.
- The paper closes with six predictions for future studies, among them whether speech is easier to understand than gesture in flickering firelight.
Why it matters
- What's now possible capability An origins question that normally ends in speculation now has an experimental form, which means it can be got wrong in public rather than argued indefinitely.
- What it limits constraint None of the six tests can date or place the transition, so even a clean sweep of positive results supports the weaker claim that firelight favours voice in living people.
- What it sets up precedent Characterising an ancient setting by measuring its optics turns physics into an evidence stream for periods where fossils and stone tools are silent on behaviour.
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The argument works by subtraction, and that is the most interesting thing about it. Researchers have catalogued more than 140 gestures in eastern chimpanzees and more than 120 in mountain gorillas [6], and the same movement can carry different meanings depending on the situation and on the history between the two animals [7]. Add planning, coordinated hunting, tool use, care for injured companions and the management of alliances [8], and the functional case for speech gets thin. Hobaiter says as much: decades of comparative work suggest you do not need language to learn from others, to organise foraging, to pass on tool and song traditions, or to navigate social politics, which makes it look as though language did not evolve for anything very useful [9]. What is left over, on this account, is the part of the day that fire created.
Take the upper bound literally and four extra hours a day is on the order of 1,460 hours a year [20], a block of social time with no daylight in it. The paper's case for why that block favoured voice over hand rests on two measured properties rather than on inference about behaviour. The first is geometry: preliminary measurements show a campfire lighting the faces nearest it while leaving people further off, or across the flames, hard to see [21], and the unsteady brightness makes gestures harder to follow [22]. The second is timing. A flicker peak at 2.7 cycles per second [13] is about 370 milliseconds per brighten-and-dim cycle [19], which is slow enough to sit alongside speech rhythm rather than inside the range where flicker becomes visual noise. Firelight also carries substantial infrared [17], and the light softens as the fire burns down, with embers suited to winding down for the night [16].
The thing this does not tell you is whether entrainment does any work. Visual neurons can lock to flickering light, and the authors raise alignment of attention and behaviour among listeners as a question rather than a result [23]. Nor do the numbers describe a Pleistocene fire; they describe fires the authors measured, and the descriptions are labelled preliminary [21]. The negative observation at the centre of the theory - that no other ape has been seen turning events into a story [11] - is an absence in a record built by people who were mostly looking for something else.
What raises this above an origin story is that the six closing predictions are not about the past [14]. Whether stories differ in pace and structure from ordinary conversation is a corpus question, and the cheapest of the three named tests to run. Whether speech beats gesture for comprehension under flickering light is straightforward psychophysics; the control it needs is steady illumination at the same average brightness, so that flicker is the only variable separating the conditions. Whether storyteller and audience synchronise more tightly is the hardest and the most interesting, because it is the step where the physics is supposed to become sociality. Hobaiter frames the ambition as escaping after-dinner speculation and asking whether we are the storytelling ape [15], and Dominy notes that firelight is a well studied chemical reaction except for the properties that hold attention [18]. On present evidence I would expect the intelligibility prediction to hold and the synchrony prediction to be where the hypothesis is decided.
What to watch
- Whether the follow-up photometry is published with fuel type, fire size and viewing distance, since the visibility and flicker figures are currently described as preliminary.
- A gesture-versus-speech comprehension test under flickering light, run against steady illumination of matched average brightness.
- Corpus work on whether story pace and structure separate cleanly from ordinary conversation, the cheapest of the six predictions to attempt.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence48
- Adoption12
- Hype gap+24
- Incentives56
- Confidence63
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The paper "Firelight and the origins of spoken language" was published in Proceedings of the Royal Society (2026), DOI 10.1098/rspb.2026.0602.
- [2]
Lead author Catherine Hobaiter is a professor in the School of Psychology and Neuroscience at the University of St Andrews; co-author Nathaniel Dominy is Charles Hansen Professor of Anthropology at Dartmouth College.
- [3]
The paper suggests fireside storytelling may have provided the key catalyst moving human communication away from the ape-like systems modern apes still use and toward uniquely human language.
- [4]
Earlier work treated stories as something people began telling after basic language was already in place; the new theory reverses that order, proposing storytelling helped human communication move beyond gestures and calls.
- [5]
The ability to control fire allowed humans to extend social time into the evenings, adding up to four hours to the day.
- [6]
Researchers have documented more than 140 gestures among eastern chimpanzees and more than 120 among mountain gorillas.
- [7]
The same ape gesture can mean different things depending on the situation and the history between the two animals.
- [8]
Apes can plan ahead, coordinate hunts, use tools, care for injured companions and navigate alliances.
- [9]
Hobaiter: "Decades of research with other species has shown us that you don't need language to learn from each other, to organize where and when to forage, to learn cultural knowledge about tools and songs, to coordinate hunting, or navigate social politics. It starts to look like human language didn't evolve for anything very useful!"
- [10]
Hobaiter: "For all their incredible, rich communication and cultures, no other ape is inventing algebra, writing King Lear or heading out into interstellar space."
- [11]
Other apes have not been observed turning events into stories.
- [12]
Firelight gives off very little blue light, the light that can lower levels of melatonin, a hormone that helps regulate sleep, which may have let people stay up together without disrupting sleep too much.
- [13]
The researchers measured how quickly firelight brightened and dimmed; the strongest pattern appeared about 2.7 times per second, near the slower end of speech rhythms.
- [14]
The paper ends with six predictions future studies could test, including whether stories have a different pace and structure than ordinary conversation, whether speech is easier to understand than gestures in flickering firelight, and whether storytellers and listeners fall more closely into sync.
- [15]
Hobaiter: thinking about how language started usually leaves researchers "in the realm of after-dinner speculation", so it is exciting to generate testable predictions and ask whether "we are the storytelling ape".
- [16]
The brightest flames could still have had some effect on sleep, but the light became gentler as the fire burned down, with glowing embers best suited to winding down for the night.
- [17]
Firelight also emits a substantial amount of infrared light.
- [18]
Dominy: firelight is the product of a chemical reaction that is extremely well studied, but not in the properties that draw attention and focus or instil harmony and cooperation; measuring those features is part of the project.
- [19]
A flicker peak of about 2.7 cycles per second corresponds to roughly 370 milliseconds per brighten-and-dim cycle.
- [20]
Four extra waking hours a day, taken as an upper bound, amounts to about 1,460 hours a year.
- [21]
Preliminary measurements by Hobaiter and Dominy show a campfire can illuminate nearby faces while leaving people farther away, or across the flames, difficult to see.
- [22]
The constantly changing brightness of firelight can make gestures harder to follow, which may have given speech an advantage.
- [23]
Because brain cells involved in vision can fire in time with flickering light, the authors wonder whether people watching the same fire might begin aligning their attention and behaviour as a storyteller speaks.
- [24]
The work provides one of the first descriptions of the fireside niche and how it could influence human behaviour.
Sources
2 independent publishers whose own reporting we read for this story.
- discovermagazine.comStorytelling Around Ancient Campfires May Have Shaped Human Language
1 article · September 1, 2026
- phys.orgFirelight may have sparked human storytelling by extending social hours
1 article · September 1, 2026
Topics and entities
Topics
- Primate Communication
- Fire and Human Evolution
- Light spectrum and sleep regulation
- Origins of spoken language
- Turning speculation into predictions
Entities
- University of St Andrews
- Proceedings of the Royal Society B
- Catherine Hobaiter
- Firelight and the Origins of Spoken Language
- Dartmouth College
- Nathaniel Dominy