BBC: A team of researchers studying the effects of ice ages on Europe’s small mammal populations has discovered that there have been several genetically distinct populations of lemmings over time. By examining DNA from fossils in cave sites in Belgium, the researchers were able to study the lemming populations during the Late Pleistocene, the era from 11 700 to around 126 000 years ago. Team member Ian Barnes of Royal Holloway University in the UK said that the researchers had originally expected to find a single species of lemming whose population had varied. Instead they found that each ice age was followed by the wholesale replacement of the previous lemming population with a new, genetically distinct population, probably from Eastern Europe or Russia, that recolonized the area. Studying the instability in the population of a small mammal that would not have been hunted by humans may help scientists understand the fates of larger animals that disappeared from Europe during the same time period. Whether megafauna species were hunted to extinction or whether environmental changes were responsible has been a matter of open debate.