Longitudinal studies of ageing in Israeli kibbutzim are particularly revealing of the importance of continuity. Successful ageing was commoner if the elderly person felt they still had a working role and responsibility for their own health. The highly developed social networks proved effective at replacing the steady loss of peers. Hence, if a kibbutz closed and the person had to go and live in a conventional city, successful ageing was much less likely.
The study being cited is by Uriel Leviatan, of the University of Haifa, who I met last year and who gave a paper at the recent ICSA conference last month. Of course, the privatization of kibbutzim—as well as the neglect of some of the retirement-aged residents at poorer communities, as described in a recent Ha'Aretz exposé—may mean that kibbutz oldtimers, once the longest living amongst the already long-living Israelis (usually second only to the Japanese), may find their life expectancies regressing to the mean, as they feel their social connections and sense of purpose and contributions to the community decline.