It’s easy to take for granted that with the flick of a lighter or the turn of a furnace knob, modern humans can conjure flames — cooking food, lighting candles or warming homes.

For much of our history, archaeologists think, early humans could only make use of fire when one started naturally, like when lightning struck a tree. They could gather burning materials, move them and sustain them. But they couldn’t start a fire on their own.

At some point, somewhere, that changed. An early human discovered that by rubbing two sticks together or striking the right kinds of rocks together, at the right angle, with the right force, they too could create fire.

Archaeologists have long wondered when that discovery happened. A new study, published in the journal Nature, provides the earliest evidence yet from a site in eastern Britain.

“This is a 400,000-year old site where we have the earliest evidence of [humans] making fire — not just in Britain or in Europe — but anywhere else in the world,” said Nick Ashton, an archaeologist at The British Museum and one of the study’s authors.

The discovery suggests early humans were making fire more than 350,000 years earlier than previously known.

“For me, personally, it’s the most exciting discovery of my 40-year career,” Ashton said.

What makes the site so unique is that Ashton and his colleagues found the raw materials for making fire — fragments of iron pyrite alongside fire-cracked flint handaxes in what looks like a hearth. A geological review found that pyrite is incredibly rare in the area, suggesting that early humans brought it to the site with the intention of using it to start fires.

“As far as we know, we don’t know of any other uses for pyrite other than to make sparks with flint to start fires,” said Dennis Sandgathe, an archaeologist at Simon Fraser University, who was not involved in the new study. “And of all the dozens and dozens of sites across Eurasia and into Africa that we’ve excavated that have fire residues in them, nobody’s discovered a piece of pyrite before.”

The ability to make fire, archaeologists agree, is one of the most important discoveries in human history. It allowed early humans to ward off predators, to get more nutrients out of food and to settle inhospitable climates.

The ability to sit around a campfire at night would have also been a catalyst for social and behavioral evolution.

“By having fire it provides this kind of intense socialization time after dusk,” said Rob Davis, an archaeologist at The British Museum and co-author of the study. “And that’s going to be a really important thing for other developments like the development of language, development of storytelling, early belief systems. And these could have played a critical part in maintaining social relationships over bigger distances or within more complex social groups.”

Davis and his co-authors don’t know the identity of the people who used the site. But less than a hundred miles to the south, archaeologists have found fragments of a skull from roughly the same time period that could have belonged to a Neanderthal. “So we assume that the fires at [the new study’s site] were being made by early Neanderthals,” said Chris Stringer, an anthropologist at the Natural History Museum in the UK and one of the study’s co-authors.

It’s possible that other early humans, including Homo sapiens, had the ability to make fires too, Stringer said. But it’s difficult to say with any degree of certainty.

Sandgathe, who’s investigated early humans’ use of fire for decades, said the discovery is very significant but he cautioned it shouldn’t be used to make broad generalizations of early human fire use.

Modern humans long assumed that the discovery of how to make fire was such an important technology that once it was found, it would have spread rapidly across the Old World like, well, fire — and from then on everybody everywhere would have been using it.

“We now realize that was way too simplistic,” he said. What’s more likely, Sandgathe said, is that different groups of early humans accidentally discovered how to make fire at different times. The knowledge may have spread or it may have been lost.

“It’s just not a linear story,” he said. “It’s a complex story of many fits and starts, over here and over there — and many millennia where nobody knew how to make fire until it was discovered again.”