The aim of this study was to ask whether there was any evidence that alcohol consumption has social benefits beyond a simple hedonic ‘high’ or anxiolytic effect. Because alcohol triggers an endorphin response, we hypothesised that it might increase the degree of social bonding (feelings of social closeness: see Dunbar and Shultz 2010; Roberts et al. 2014) and this might have implications for how happy and socially engaged people become. The evolutionary significance of this lies in the fact that our social networks provide us with the single most important buffer against mental and physical illness (House 2001; Fowler & Christakis 2008; Holt-Lunstad et al. 2010; Tilvis et al. 2012; Kim et al. 2016). We asked whether the frequency of social alcohol consumption (indexed by the frequency of drinking in pubs) or the type of venue (‘locals’ vs bars) influenced people’s social experiences and their wellbeing.

The survey data suggest that respondents who have a ‘local’ that they visit on a regular basis are more socially engaged, feel more contented in their lives, and are more likely to trust other members of their community. On some, but not all of our social measures, those who drink ‘casually’ were more socially engaged than those who didn’t drink at all, suggesting that there are independent effects due to being a drinker and having a regular drinking venue. Overall, the number of close friends that people have (those on whom one can count for support in times of crisis, often known as the ‘support clique’) is of the same magnitude as has been found in previous studies (present study: 6–7; previous studies: 4–6: Sutcliffe et al. 2012). However, those who did not have a ‘local’ had significantly smaller social networks and felt less engaged with, and trusting of, the communities within which they were embedded. The path analysis suggested that feeling satisfied with life and how often one visits a pub both independently influence a set of variables associated with happiness and trust in others, which in turn influence engagement with the community and personal network size.

The results of the pub behavioural study corroborated the findings from the national survey: people drinking in community pubs (or ‘locals’) felt significantly more engaged with their local community than those drinking in city centre bars. More importantly, those in ‘locals’ were more likely to be in ‘conversational’ sized groups, whereas those drinking in city centre bars were in groups that significantly exceeded not only natural conversation group size but also the typical size of the support clique. This difference in social environment may be expected to have significant effects on the formation and maintenance of social bonds. In large city centre venues, people were much less engaged with each other, moving rapidly from one brief conversation to another. As a result, they have less time to get to know their social companions or establish relationships with them. We interpret this as being at least part of the explanation for the fact that those who do not have a ‘local’ they visit regularly feel less engaged with their community, feel less satisfied with life and have smaller support networks. This may have wider implications because the size of support networks (cliques) scales up to predict the size of the extended social network (or active network) (Zhou et al. 2005; Sutcliffe et al. 2012).

It is always possible that these differences in behaviour might be due to personality differences. Extraverts, for example, have larger social networks than introverts, although the average quality of their relationships is typically weaker as a result (Roberts et al. 2008; Pollet et al. 2011). We did not include measures of personality because we did not want to overburden our participants, and hence we cannot evaluate this possibility here. However, we take the view that any relationship between particular personality dimensions and our dependent measures (happiness, social engagement) is likely to be mediated by the role of social drinking, or at least that the two effects are independent and additive. This remains to be tested, however.

Although there is considerable evidence that moderate alcohol consumption can enhance some aspects of cognition, including memory, mental arithmetic and inhibition, even though excessive consumption inevitably has deleterious effects (Christian et al. 1995; Henrie et al. 1996; Launer et al. 1996; Elias et al. 1999; Galanis et al. 2000; Krahn et al. 2003; Schreckenberger et al. 2004; Easdon et al. 2005; Lang et al. 2007; Sinforiani et al. 2011), we could detect no effect on people’s assessment of strangers’ approachability, trustworthiness or attractiveness on the basis of facial cues, at least within the modest range of alcohol consumption that we sampled. There is an important contrast between most laboratory studies of the effects of alcohol, where subjects are required to consume large doses of alcohol (in some cases, by intravenous injection) in artificial settings, and our real-world observational study involving mostly moderate social drinking. The lack of any effects of social alcohol consumption on social cognition and the positive findings on the more general aspects of life satisfaction and social engagement outside the immediate pub environment suggests that the role of alcohol is more likely associated with the maintenance of existing relationships than with the initiation of new ones with strangers.

Because the endorphin system is central to social bonding in primates (including humans) (Keverne et al. 1989; Panksepp 1999; Depue and Morrone-Strupinsky 2005; Dunbar 2010; Machin and Dunbar 2011; Nummenmaa et al. 2016) and seems to have a direct effect on the body’s capacity to resist endogenous and exogenous disease threats (Sarkar et al. 2012; Kim et al. 2016), anything that triggers the endorphin system is likely to have been adopted once discovered. This is not, of course, to suggest that excessive alcohol consumption does not have serious health consequences.

Aside from direct health benefits that might arise from up-regulating the endorphin system, the principal benefit of the social consumption of alcohol may thus be that it acts much like the many other endorphin-stimulating activities that we use for social and community bonding (notably laughter, singing, dancing, and even storytelling: Dunbar et al. 2012; Tarr et al. 2015, 2016; Pearce et al. 2015; Dunbar et al. 2016). This is not to suggest that alcohol consumption is an adaptation in the formal biological sense, but rather that we discovered how it could be used to trigger a mechanism (the endorphin system) that is an adaptation for social bonding. Indeed, there is now a widespread view among archaeologists that cereal cultivation was first started in order to brew beer rather than to provide food (Dietrich et al. 2012; Hayden et al. 2013). We suggest that, like these other social bonding activities, the consumption of alcohol, once it had been discovered, came to be adopted as part of the complex set of activities and rituals associated with bonding our (by monkey and ape standards) large social communities.