This series of posts starts - at the start - with the simple question of why we even need strong relationships. This might seem like asking why do we need food, water or oxygen. But, although people often talk up relationships, their behaviour tells a different story.

Likening relationships to basic physiological needs, some might argue, is a step too far. After all if I was stranded on a desert island I'd survive longer with just fresh drinking than with only a friend to talk to. But that isn't a fair comparison. For many of us in modern Western societies, our basic physiological needs are fulfilled and it is on higher goals that our mental and physical health depends. When arguing relationships are as important to health as exercise and nutrition, it is really a reflection on the relative comfort we enjoy.

Physical wear and tear
So what does the research tell us? Carol Ryff has been carrying out research into the connection between relationships and health for some time. In one study which followed 10,317 people from birth over 36 years, data on social relationships was collected along with biological markers important for indicating wear and tear on the body. Measures included systolic blood pressure, urinary cortisol levels and epinephrine levels. The data support the idea that negative relational experiences are associated with greater wear and tear on the body (Hauser et al., 1993).

Like any good scientist you'll be saying: well there may be an association but does that mean that poor relationships actually cause poor health? As it's not ethical to deliberately subject humans to desert island conditions - unless it's for TV of course - we just don't know.

That said, there's evidence from measuring oxytocin in animal studies. Levels of oxytocin have been causally linked to lowering blood pressure and heart rate (Ryff et al., 2001). Indeed in a recent study a relationship was found between poor social relationships and oxytocin levels (Taylor et al., 2006).

If living a longer and happier life relies on our relationships, how exactly do we start these relationships? In the next few posts I'll move on to look at what research is telling us about finding both friends and partners.

» This post is part of a series on the psychology of relationships.

See also: Review of The Impact of Inequality: How to Make Sick Societies Healthier by Richard G Wilkinson (The Guardian)

References

Hauser, R., Carr, D., Hauser, T., Hayes, J., Krecker, M., Kuo, H., et al. (1993). The class of 1957 after 35 years: Overview and preliminary findings (Center for Demography and Ecology Paper 93-17). Madison: University of Wisconsin.

Ryff, C. D., Singer, B. H., Wing, E., Dienberg Love, G. (2001) Elective affinities and uninvited agonies. In: C. Ryff, & B. Singer (Eds.). Emotion, social relationships, and health. Oxford University Press New York.

Taylor, S.E., Gonzaga, G.C., Klein, L.C., Hu, P., Greendale, G.A., Seeman, T.E., et al. (2006) Relation of oxytocin to psychological stress responses and hypothalamic-pituitary-adrenocortical axis activity in older women. Psychosomatic medicine, 68(2), 238-45.