“A long-held myth regarding development is that as people age, they all become alike. This view is refuted by the third principle of adult development and aging, which asserts that as people age, they become more different from each other rather than more alike. With increasing age, older adults become a more diverse segment of the population in terms of their physical functioning, psychological performance, and conditions of living. In one often-cited study, researchers examined a large number of studies of aging to compare the amount of variability in older versus younger adults (Nelson & Dannefer, 1992). This research established that the variability, or how differently people responded to the measures, was far greater among older adults. Research continues to underscore the notion that individuals continue to become less alike with age. Such findings suggest that diversity becomes an increasingly prominent theme during the adult years, a point we will continue to focus on throughout this book.

The fact that there are increasing differences among adults as they grow older also ties into the importance of experiences in shaping development. As people go through life, their experiences cause them to diverge from others of the same age in more and more ways. You have made the decision to go to college, while others in your age group may have enlisted for military service. You may meet your future spouse in college, while your best friend remains on the dating scene for years. Upon graduation, some may choose to pursue graduate studies as others enter into the workforce. You may or may not choose to start a family, or have already begun the process. With the passage of time, your differing experiences build upon each other to helpmold the person you become. The many possibilities that can stem from the choices you make help to illustrate that the permutations of events in people’s lives are virtually endless. Personal historiesmove in increasingly idiosyncratic directions with each passing day, year, and decade of life.”

I didn’t post this quote when I first blogged Adult Development and Aging mainly because I figured the insight was probably important enough to merit a post of its own, but also because I figured that if they dealt with this aspect in more details later on I’d rather wait until then to handle the specifics. Anyway it’ll be a while until I get to that stuff and I find myself thinking about these things now and then these days. I’m mostly thinking about how this stuff relates to how we form friendships and establish romantic partnerships. As people age it seems to me that they become less likely to meet that ‘someone who’s just right for me’; and not just because of the work of their romantic rivals. Because of the increasing variation in the behaviours, preferences and outcomes perhaps people who are aging gradually realize that it is strategically optimal for them to become more tolerant, more permissive, and so they implicitly gradually implement such strategies to increase their chances – but that’s hardly always the case and to the extent that it is, the process likely involves them making compromises that perhaps would have been unnecessary if the partners in question had met a decade earlier in their lives. (Though I may here underestimate how much work is required to make a relationship last that long.) Path dependence matters a lot when it comes to both friends and relationships. As I’ve underscored before here on the blog a ‘new’ friend is most often introduced by an ‘old’ friend or acquaintance, and most people rely to a very great extent on their existing social network when they want to make adjustments to it. Over time people’s social networks become entrenched; it gets harder to find and keep new friends not only because every potential new friend is competing for your attention with the whole set of friends you already have, but also because the potential new friend becomes increasingly less likely to share your interests or preferences over time, at the very least when compared with the people with whom you frequently interact. Interaction affects preferences and behaviours, for friends, family and partners alike.

Though people in general tend to become more different from each other as they age, I tend to believe that cohabitating partners do not and that they on the other hand tend to become more alike over time. This is of course because they tend to form similar habits, do similar stuff. Another noteworthy dynamic is the ‘I’ve known you a long time and I’ve invested a lot in this relationship at this point, so it doesn’t matter as much to me that you’re not as compatible as I’d like you to be as it would if we’d only just met’. Of course there’s also (hopefully) the frequent feedback from the partner, making you less likely to stray far away from the partner ideal of the other party – such feedback is harder to obtain for people not in a relationship. There’s also the ‘my previous partner/parents/whatever behaved this way (/cheered for the Green team) and so if you don’t behave this way we won’t be compatible’. Politics, religion and similar stuff’s really important, and often people’s opinions about these matters crystallize over time. If crystallization of this kind of stuff takes place over time, it will generally harm outsiders (singles) and benefit insiders (couples); the people in romantic relationships become more alike over time and so they’ll feel a closer bond to each other as time goes by, and the aging single will in the absence of a romantic partner often obtain much of the relevant social feedback from other singles who may not be able to give useful feedback regarding this aspect of life. For example a single aging man may start to think that his religious- or political views cannot possibly matter a great deal to a potential partner because such things do not matter a great deal to the people with whom he usually interacts. It should perhaps also be noted that the potential decreased compatibility of the remaining outsiders with the insiders makes the outside option become less attractive to the insiders (making them less likely to break up with their partners).

About a decade ago I had relatively few problems talking to and interacting with my extended family (cousins, uncles). These days it’s a pain for me to do it for any period of time, and I found myself actively avoiding the presence of some of these people this Christmas. To the extent that I did interact with them I was polite and helpful, but I did avoid them and I did not want to spend time with them. I find myself worried about where I’ll end up in another decade if things do not go well. Or is it ‘if things do go well?’


December 30, 2012 - Posted by | Personal, Psychology, rambling nonsense, Random stuff


  1. The Nelson ref sounded interesting, because I was wondering what might be meant by heterogeneity – in some respects, we’d expect more heterogeneity because of a random walk (we’re all alike as babies, we cry a lot), analogous to Gould’s argument about the complexity of organisms being produced by evolution, but in others we might expect more homogeneity as our bodies fall apart (perhaps IQ gets compressed as we age, for a similar set of reasons: as young people we can be the most brilliant possible, but also just retarded, while even the most brilliant old people are still way below their youthful peaks).

    So I requested a copy:

    Overall, seems as described.

    Comment by gwern | January 2, 2013 | Reply

    • I downloaded the paper – I may have a look at it after my exams.

      “in some respects, we’d expect more heterogeneity […] in others we might expect more homogeneity as our bodies fall apart” – this is a very good point; it’s not really an either/or.

      A related point though is that although our bodies do tend to ‘fall apart’ in foreseeable and similar ways, there’s still a lot of variation when it comes to how fast the process progresses and which biological systems get hit hardest. Aging is a complex process involving many different organ systems – a point I also tried to get across in the book posts. Not all of the biological processes that go on in our bodies are equally sensitive to e.g. specific behavioural interventions like, say, a change in diet.

      Comment by US | January 3, 2013 | Reply

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