A wonderful fringe collection of researchers including scientists from the Academy of Sciences of the Czech Republic, Libechov; at Stellenbosch University, South Africa; from the National Museums of Scotland, Edinburgh and the University of Calgary, Canada, led by Professor Searle of the University of York discover that end-Ice Age colonization of Britain by small mammals generates a remarkably ‘human-like' geographic pattern of genetic variation.

Dr Searle's work in 2008, analysed the genes of 328 mice from 105 localities in the UK. The difference in mitochondrial DNA shows that one distinct strain of mice from northern and western peripheries of the British Isles probably arrived with the Norwegian Vikings. Another strain of mice found on mainland Britain show some of the same DNA sequences as mice from Germany believe this might be a link to Bronze Age human migrations, beginning about 2300 BC.

And research into the movement of small mammals, such as  field  (left) voles and shrews, at the end of the last Ice Age, could provide important new clues to resolve the debate.

The Celtic Fringe of Britain: insights from small mammal phylogeography study showed that mitochondrial DNA lineages of the three small mammal species - bank vole,(right) field vole and pygmy shrew (left) - form a ‘Celtic fringe'. The researchers say that these small mammals colonized Britain, when still connected to continental Europe, in a two-phase process at the end of the last Ice Age.

The research says there was partial replacement of the first wave of colonists by a second -- the two groups are too genetically distinctive to have evolved from each other while in Britain. The sudden change in climate at the end of the last Ice Age may have been important to allow the second type to invade Britain and partially replace the first type.

These events at the end of the Ice Age resulted in a peripheral geographical distribution of the first colonists - the ‘Celtic fringe'. The distribution mirrors the genetically distinctive human Celtic fringe found in Scotland, Northern Ireland, Eire, Wales, the Isle of Man and Cornwall.

Professor Searle, of the University's Department of Biology, said: "We believe this study of the distribution of small mammals can help us to understand why humans in the British Isles form a Celtic fringe. This study represents a novel example of the way that study of animals can help to shed light on human history."
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The paper researchers  were Jeremy B. Searle; Petr Kotlik; Ramugondo V. Rambau; Silvia Markova; Jeremy S.Herman; Allan D.McDevitt is published in Proceedings of the Royal Society B.