People with the lower IQ score are likely to have manual labor jobs which are generally more deadly and stressful to the body over time versus a desk/office job or one in academia; such a job is less deadly and such positions are held by people with higher IQs. This is why, I think, people with lower iq have a lower life expectancy, for like a better term, as per the mentioned Scottish participants.,(reply>), That's definitely one factor. Other factors that come to mind are 1.) people with some serious health problems having reduced IQs, 2.) managing health conditions being more difficult for less intelligent people (diabetes management comes to mind as something that is a huge headache even for intelligent people), and 3.) particularly unintelligent people dying in more accidents due to poor judgement.,(reply>), Yes and they're probably paid more so they can eat healthier and they have less vices to help them deal with hardships. Many of these people with desk jobs would starve if they had to do manual labour.