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 half a million years ago.

“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.”

Professor Chris Stringer, a paleontologist at the Natural History Museum, holds one of the 32 black flint artifacts found in eastern England that date back 700,000 years. Ancient tools found in Britain show that humans lived in northern Europe 200,000 years earlier than previously thought.

Jim Rose, a professor at the University of London who also was involved in the study, said that 700,000 years ago England was still connected to the European mainland and enjoyed periods of balmy weather between the time that massive glaciers swept through the area, freezing and reforming the landscapes.

During such thaws, he said, early humans would have been able to migrate from the Mediterranean to England, where there were mild winters, flat landscapes and major rivers.

Before that discovery, the earliest traces of humans in Europe north of the Alps were dated to about 500,000 years ago, and included flint artifacts and even some human remains that were discovered in Bosgrove on the southern coast of England.

The earliest traces of human presence in southern Europe are at least 800,000 years old and include materials that were discovered in Atapuerca, Spain.