LONDON – Ancient tools found in Britain show that humans lived in northern Europe 200,000 years earlier than was previously known, at a time when England’s climate was warm enough to be the home of lions, elephants and saber-tooth tigers, scientists announced Wednesday.

The 32 black flint artifacts, found in river sediments in Pakefield in eastern England, date back 700,000 years and represent the earliest unequivocal evidence for human presence north of the Alps, the scientists said.

The finding dashes the long-held theory that humans did not migrate north from the relatively warm climates of the Mediterranean region until 500,000 years ago, the scientists said.

“The discovery that early humans could have existed this far north this long ago was startling,” said Chris Stringer, a paleontologist at the Natural History Museum, one of four British scientists who took part in the study and announced the finding at a news conference in London. Their discovery is detailed in the scientific journal Nature.

“Now that we know this, we can search for the remains of these people, knowing that we may find them,” he said. “Their arrival in northern Europe could have happened even earlier. We have a whole new area of research opening up to us.”

Before that discovery, the earliest traces of humans in Europe north of the Alps were dated to about 500,000 years ago.