A recent discovery in Britain isn't much to look at. It's just a dirt pit containing broken flint hand axes and tiny pieces of the mineral iron pyrite. But those little fragments potentially upend our understanding of human development. "For me, personally, it's the most exciting discovery of my 40-year career," Nick Ashton told NPR. He is an archaeologist. He is one of the lead researchers on the dig site in Suffolk County. He co-authored a report on his findings. It was published in the journal Nature. The site is more than 400,000 years old. It contains evidence that repeated fires burned on that patch of soil. For years, Ashton’s team ran tests to see if the evidence could be explained by multiple forest fires. They found nothing that could lead to such a deduction, however. That left them with only one explanation. "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," Ashton said. The chief clue? That's iron pyrite. It’s extremely rare in the area. That suggests the ancient people who lived there brought it from elsewhere for a particular purpose. Like flint, iron pyrite can be used to create sparks and start a fire. Combined with evidence that fires in excess of 1,292 degrees Fahrenheit had scorched the ground in the area, Ashton’s team concluded that prehistoric humans must have started the fires. If so, it pushes back our earliest date for that milestone by 350,000 years. Reflect: How might discovering something new about the past change the way people understand who we are today? Gif of fire burning from Giphy.