Fire, evolution
and us.

Before there was a hearth

“Discovery”
took stages.

There was no single moment when humanity discovered fire. Our ancestors first encountered natural fires. Later they could bring embers back to a camp and keep a flame alive. Much later, people learned to start fires when they wanted them. These are different abilities, and their traces in the ground are difficult to tell apart from natural burning.

At Wonderwerk Cave in South Africa, burned bone, stone, sediment and ash have been reported in a layer dated to about one million years ago. A 2026 study using bone luminescence proposes additional early fire evidence at the cave. These findings concern fire associated with hominin activity; they do not show that people made the fire. At Barnham in England, a 2026 Nature study describes a different kind of evidence: heated sediment and flint alongside iron pyrite, a mineral that can strike sparks. The authors argue this is the earliest direct evidence yet of people making fire, around 400,000 years ago.

Keep the distinctions: encountering fire, using or maintaining it, and making it are not the same milestone. The archaeological dates continue to be investigated.

Food and bodies

Cooking changed
the equation.

Heating food can make some nutrients easier to access, soften fibrous foods, reduce the work of chewing and kill many pathogens. Researchers have proposed that cooking helped our ancestors get more usable energy from food, with consequences for teeth, jaws, digestion, daily time and the energy available to a growing brain. Fire could also make foods usable that were difficult or unsafe to eat raw.

That is a powerful evolutionary argument, but it is not a settled one-cause story. The timing of regular fire use, habitual cooking, changes in diet and changes in human anatomy do not line up neatly in every place. Meat, food processing, ecological change and social organisation also matter. The cooking hypothesis is worth taking seriously while leaving room for competing explanations and new archaeological evidence.

The effects also run outward. Cooking changes the foods humans can choose to eat; it does not automatically mean that every animal eaten was thereby changed through natural selection. Hunting, habitat alteration, deliberate burning, and later herding and domestication create different pressures on other species. Those relationships belong in this story too.

A new proposal

Why might burns
not kill us?

The video that opened this inquiry is an Imperial College London interview with Dr Joshua Cuddihy, a medical doctor and honorary clinical research fellow. Cuddihy and nine co-authors propose the “Burn Selection Hypothesis”: because human ancestors lived close to fire, they may have faced repeated small and survivable burns. Over many generations, that risk could have favoured changes in wound healing, inflammation, pain and infection response.

Their 2026 BioEssays paper compares gene-expression data from burned and unburned tissue, then examines evolutionary signals in genes associated with burn response. The authors identify candidate genes and argue that burn exposure could be one reason human healing responses work as they do. They also say the same genes may respond to other kinds of injury, so fire is not yet isolated as the cause. It is an interesting hypothesis with evidence to test, not a demonstrated account of our ancestry.

What I want to ask: how much of the pattern is distinctive to burns, what other evolutionary pressures could explain it, and what evidence would let us tell?

Watch Dr Joshua Cuddihy explain the proposal ↗

More than calories

Fire made
new surroundings.

A flame gave warmth and light after sunset. A maintained fire could help deter predators, make colder places more habitable and bring people into a shared pool of light. Ethnographic research on contemporary Ju/’hoansi communities has found that evening talk around fires often ranges further than daytime conversation. That does not prove the same conversations took place in prehistory, but it offers a grounded way to think about how light might reshape social time.

Fire also changes landscapes. People in many societies have used carefully timed burns to alter vegetation, encourage useful plants, open paths and change where animals feed. The outcome depends on the ecology, the season and the people’s knowledge. The same tool can sustain a landscape, injure it or escape control.

Once heat could be produced on demand, it became part of an expanding technological chain: shaping and hardening materials, firing clay, working metals, making glass, and eventually powering engines and industries. Each change reorganised human work and relationships with other species and landscapes. The story of fire keeps widening.

Where the energy comes from

A flame carries
old sunlight.

Most of the wood and plant matter used in an ordinary fire contains energy first captured from sunlight through photosynthesis. Plants store some of that energy in chemical form as they grow. Combustion rearranges the fuel with oxygen and releases part of that stored energy as heat and light. In that sense, a wood fire is sunlight gathered by a plant and released later in a form people can use.

The Sun is not itself burning in the chemical sense: its energy comes from nuclear fusion. And not every flame uses recently grown biomass; fossil fuels are ancient stores of energy, and some fuels have other geological origins. But the chain from sunlight, to living matter, to a tended flame is a striking way to see fire as energy moved through life and culture.