I actually had never looked up the studies Wolf was referencing before (naively, perhaps, I trust the guy to have reviewed the literature). But I think he is probably referencing this:
>Researchers at Brigham Young University and the University of North Carolina at Chapel Hill pooled data from 148 studies on health outcomes and social relationships — every research paper on the topic they could find, involving more than 300,000 men and women across the developed world — and found that those with poor social connections had on average 50% higher odds of death in the study's follow-up period (an average of 7.5 years) than people with more robust social ties. That boost in longevity is about as large as the mortality difference observed between smokers and nonsmokers, the study's authors say.
>Researchers at Brigham Young University and the University of North Carolina at Chapel Hill pooled data from 148 studies on health outcomes and social relationships — every research paper on the topic they could find, involving more than 300,000 men and women across the developed world — and found that those with poor social connections had on average 50% higher odds of death in the study's follow-up period (an average of 7.5 years) than people with more robust social ties. That boost in longevity is about as large as the mortality difference observed between smokers and nonsmokers, the study's authors say.
http://www.time.com/time/health/article/0,8599,2006938,00.ht...