So British scientists have proved some bones found in Magdeburg Cathedral to be the remains of our Anglo-Saxon Princess Eadgyth. At least, science helped. Eadgyth was known to have been buried in Germany: in 2008 archaeologists there opened her tomb, and found a lead box containing bones from a woman of the right age, with an inscription saying they were her remains.

In a more innocent age, this might have been enough to settle the case. But today we like science, the full CSI drama. Yet before we get too cynical about Eadgyth (the science showed that the woman in Magdeburg probably grew up in southern England), we should recognise that the technique used is transforming the way we think about our ancient and early historic past. Something big is going on.

Most of Eadgyth's skull was missing, but her upper jaw had survived. This enabled scientists to examine strontium and oxygen isotopes in her teeth. These are fixed in enamel as it grows, so the isotope signature reflects the source of these elements (ingested through food and drink): and as different teeth grow at different ages, you can map changes through adolescence. The significance of this is that the isotopes vary according to temperature, altitude, distance from the sea and local geology. Match teeth with landscape, and you chart early residence and movements.

Fifty years ago, archaeologists ascribed every change in our ancient past to immigration: farming, metals, a new style of cook pot were seen as the marks of waves of invaders. The subsequent backlash in our thinking saw invasions vanish, and our ancestors branded triumphant, if insular, inventors. Tooth analysis has blown apart this simple polarity. The turning point came in 2003, when Carolyn Chenery and Jane Evans at the NERC Isotope Geoscience Laboratory near Nottingham analysed the remains of a man buried near Stonehenge in 2300BC. His grave contained an exceptional collection of artefacts: and his teeth showed he was born in central Europe.

There has since been a succession of revelations. Recent examples include a Goth from the Black Sea area who died in Roman Bristol, an African on Hadrian's Wall and a Viking woman in Yorkshire. More than 50 brutally murdered young men buried in a pit outside Weymouth also turned out to be Vikings. The science works with animals, too: cattle at a big settlement near Stonehenge had been driven there over huge distances.

This is adding up to a new view of how people in the past moved around. The analysis of teeth supports neither extreme of migration or isolation, but rather a pattern where small groups or individuals travelled frequently across cultural and geographical divides. This is about residence and mobility, not ethnicity. Nonetheless, it seems that, in modern terms, Europe was always a multicultural place.

Mike Pitts is editor of British Archaeology