Anne Magurran started her career as an ecologist counting moths in an ancient woodland in northern Ireland in the 1970s, when the study of biological diversity was a very young science. Later she studied piranas in a flooded forest in the Amazon. Turning descriptions of the natural world into meaningful statistics is a challenge and Anne has pioneered the measurement of bio-diversity. It’s like an optical illusion, she says. The more you think about bio-diversity the more difficult it is to define. After a bout of meningitis in 2007, she set up BioTime, a global open access database to monitor changes in bio-diversity over time and is concerned about ‘the shopping mall effect’. Just as high streets are losing their distinctive shops and becoming dominated by the same chain stores, so biological communities in different parts of the world that once looked very different are now starting to look the same.