Mathers, a senior scientist in the Evidence for Information and Policy Cluster. “We need to wait to be persuaded by evidence.” His colleague Dr Tiers Boerma, Director of the WHO Department of Health Statistics and Informatics, added: “People should understand that some of the numbers are very different and the WHO can’t jump with any academic publication that states a different number.” However, said Mathers, “the fact that IHME has pushed the envelope with some of these analyses is stimulating”. One of the main themes, said Murray, was “incredibly rapid change in the leading causes of death and the pace of that change is a lot faster than we expected it to be”. Reduced fertility and longer life expectancies have meant a rise in the mean age of the world’s population in a decade, from 26 years old to almost 30. It has been dramatic in Latin America, for instance, where countries like Brazil and Paraguay had life expectancy of below 30 in 1970 and almost 64 in 2010. That is a 35-year increase in the mean age of death over four decades. “In a place like Brazil, the speed of change is so fast that most institutions are ill-equipped to deal with it,” Murray said. The second theme, entwined with it, is the shift outside Africa from communicable diseases and the common causes of mother and baby deaths to what are sometimes termed “lifestyle” diseases,