Why do some people seem to get old before their time while others look like they haven’t aged a day since college? A team of researchers from Duke University studied a nearly 1000 people born within a year of each other and found a huge gulf in the speed at which their bodies aged. The subjects were from the same town in New Zealand and were all born in 1972-73. The scientists looked at 18 different ageing-related traits when the group turned 26, 32 and 38 years old. They measured everything from kidney and liver function to cardiovascular fitness and the condition of their gums.

They found that at the age of 38, the people's biological ages ranged from the late-20s to those who were nearly 60. In other words some people had almost stopped ageing during the period of the study, while others were gaining nearly three years of biological age for every twelve months that passed.

One particularly interesting finding of the study was that the people who were physiologically older looked older, at least according to Duke undergraduates who were asked to guess their ages from their pictures.

The researchers hope this work will help them prevent diseases by slowing down the the aging process.