Why do Humans use Drugs? Part 2 (Alcohol)
Dr Gurjot Brar adapts his essay which was presented before the Addictions Faculty of The College of Psychiatrists of Ireland. Edited by Prof. Henry O'Connell.
Our sincerest thanks to Paul St John-Smith and Riadh Abed for their advice, knowledge and expertise not only in the production of this article but for everything they do for the field.
Although reading Part 1 is not required to appreciate this article, for those who missed it here it is:
Why do Humans use Drugs? - Part 1
Our sincerest thanks to Paul St John-Smith and Riadh Abed for their advice, knowledge and expertise not only in the production of this article but for everything they do for the field.
Alcohol - Humanity’s Oldest Social Technology?
When it comes to human behavior, few substances have such deep evolutionary, cultural, and biochemical roots as alcohol. With the exception of religious prohibitions, alcohol consumption has been documented in nearly every society known to anthropology. It predates tea and coffee by millennia. And while high-alcohol spirits are relatively recent—thanks to distillation and fortification technologies—humans have been fermenting things for a very long time.
Large-scale alcohol production can be traced back at least 9,000 years. Archaeological findings at Göbekli Tepe suggest early Neolithic cultures may have brewed beer as part of ritual gatherings (Dietrich & Dietrich, 2019). But this likely wasn’t the beginning. Small-scale fermentation probably occurred even earlier (Dunbar, 2022). Intriguingly, some researchers propose that the domestication of grains may have been driven not by bread, but by beer production (Hayden et al., 2013)—suggesting that alcohol may have been a central motivator in the development of agriculture.
Zooming out to a broader biological scale: alcohol is not uniquely human. Overripe fruits in the wild naturally ferment, producing alcohol concentrations of around 4% ABV—similar to many modern beers. This isn’t accidental. Fermentation by yeast helps defend fruits against microbial spoilage (Thomson et al., 2005). And our ability to metabolize this ethanol isn’t new either: the enzyme alcohol dehydrogenase (ADH4), crucial for breaking down ethanol in the stomach, underwent a key evolutionary mutation approximately 10 million years ago—right around the time African Apes began spending more time on the forest floor, foraging for fallen fruit (Carrigan et al., 2015). The exploitation of fermented fruits from the forest floor likely continued to be a major source of high-energy foods up until the genus Homo appeared around 2 million years ago (Dunbar, 2022).
From an energy perspective, fermented fruits offered a caloric windfall. Ethanol increases caloric density and is more readily absorbed than complex carbohydrates. This would have been advantageous for pre-Homo species living in fluctuating foraging environments (Dunbar, 2022). But the evolutionary story doesn’t stop at metabolism. The persistence of alcohol use across societies—despite its well-documented costs—suggests a compensating benefit.
The exploitation of fermented fruits from the forest floor likely continued to be a major source of high-energy foods up until the genus Homo appeared around 2 million years ago (Dunbar, 2022).
Alcohol, Evolution, and the Architecture of Connection
According to biological anthropologist and evolutionary psychologist Robin Dunbar, one overlooked advantage is social cohesion. Alcohol functions as a “social lubricant,” facilitating group bonding during communal activities, rituals, and shared meals (Dunbar, 2022).
Recent behavioral data supports this. A large national survey in the UK found that individuals who regularly visited a “local” pub reported significantly higher levels of happiness, life satisfaction, and social engagement. These individuals also had larger close friendship networks than those who abstained from alcohol or drank in isolation. Notably, frequency of pub attendance—not just alcohol consumption per se—was the strongest predictor of these social benefits. From the representative sample of British pubs, 87% of patrons were “modest” drinkers (i.e., consuming within recommended limits). Social outcomes were more favorable in traditional community pubs than in city-center bars, suggesting that the environment of drinking plays a key role in shaping outcomes. In other words: it's not just what you drink, but where and with whom.
To be clear, none of this downplays alcohol’s risks—addiction, liver disease, cognitive impairment—but it does highlight a deeper historical and biological logic to why humans keep returning to the bottle. Alcohol’s role in group cohesion, social bonding, and even evolutionary fitness might help explain its persistence, even in the face of modern medical warnings.
One of the most consistent predictors of health, longevity, and psychological well-being isn’t diet, exercise, or even genetics—it’s social connection. The number and quality of close friendships a person maintains has been repeatedly shown to correlate with lower rates of morbidity, better immune response, and greater life satisfaction (Dominguez & Arford, 2010; House, 2001; Pinquart & Duberstein, 2010; Smith & Christakis, 2008). This isn’t just a quirk of modern life; it’s an ancient mammalian inheritance. Strong social bonds enhance survival in a variety of mammalian species, from horses to dolphins to baboons (Cameron et al., 2009; Crockford et al., 2008; Frère et al., 2010).
Strong social bonds enhance survival in a variety of mammalian species, from horses to dolphins to baboons (Cameron et al., 2009; Crockford et al., 2008; Frère et al., 2010).
Alcohol, while not necessary for connection, appears to have historically amplified these bonds. Hockings and Dunbar (2020) describe drinking as “a long and social affair,” embedded in rituals of cooperation, cohesion, and mutual celebration. The prevailing image of alcohol as a vehicle for selfish pleasure-seeking doesn’t quite square with the historical or cross-cultural data. Across time and culture, alcohol has more often been consumed in communal rather than individual settings—at feasts, religious rites, communal meals, and local taverns.
One of the most consistent predictors of health, longevity, and psychological well-being isn’t diet, exercise, or even genetics—it’s social connection.
We actually got to talk with the legendary Robin Dunbar earlier in the year!
A Conversation with Robin Dunbar
First and foremost, thank you Robin for agreeing to take part in this interview. It is an amazing privilege for us to be able to ask you some questions for our Substack.
Drug Use Through an Evolutionary Lens
So how should we understand substance use more broadly? The evolutionary perspective adds explanatory depth to existing biological and psychological models of addiction. At its core, the insight is simple: human vulnerability to psychoactive substances stems from a mismatch between our evolved reward systems and the potency of modern drugs. These substances effectively "hijack" ancient neurological circuits originally designed to reinforce behaviors like bonding, eating ripe fruit, or seeking warmth and safety.
This mismatch is no small matter. Our brains evolved in environments where rewards were rare, effortful, and time-consuming to obtain. Modern drugs—high-potency, rapidly acting, and easily accessible—create supernormal stimuli that overwhelm these evolved systems. The result? Dysregulated behavior, tolerance, dependence, and, in many cases, addiction.
Human vulnerability to psychoactive substances stems from a mismatch between our evolved reward systems and the potency of modern drugs.
Recognizing this mismatch opens the door to smarter, more humane public policy. Rather than relying exclusively on punitive approaches, an evolutionary-informed strategy encourages upstream investment in public health: prevention, education, and early intervention. The work of Babor et al. (2003) on alcohol harm reduction provides a promising template. Through demand reduction (e.g., pricing strategies, education) and supply control (e.g., licensing, restricted sales hours), significant gains were made in reducing alcohol-related harms—particularly in areas like drink-driving. These same levers can and should be explored in other domains of drug use (Ghodse, 2003).
Rethinking Addiction: From Stigma to Systems
Perhaps most importantly, an evolutionary framework helps destigmatize substance use disorders. Instead of viewing addiction as a personal failing, it reframes it as a predictable consequence of biological susceptibility intersecting with environmental stressors. This aligns neatly with the biopsychosocial model already common in mental health practice, but expands it—urging us to consider how universal human traits interact with modern pressures and artificial substances.
For instance, social defeat, isolation, or a perceived lack of belonging can increase vulnerability to substance misuse. When individuals struggle to compete or connect socially—particularly in adolescence, a period of heightened neural plasticity and risk-taking—drugs may serve as maladaptive coping tools. These are not moral failings; they’re survival strategies gone awry in a mismatched environment (Durrant et al., 2009).
Treatment, then, should be as multifaceted as the problem itself. Biologically, this may involve medications that target the brain’s reward circuits. Psychologically, we can focus on improving self-regulation, enhancing coping strategies, and disrupting conditioned cues associated with drug use. Socially, we must address the environments that make maladaptive behavior more likely—poverty, marginalization, lack of community, and chronic stress.
Crucially, the evolutionary framework reminds us that natural rewards—friendship, purpose, connection—still matter. These "primary goods" (Ward & Stewart, 2003) aren’t just nice-to-haves; they’re foundational to any effective treatment strategy. A person with strong social ties and a sense of belonging is less likely to chase synthetic highs, and more likely to perceive a real cost in destructive behavior.
Crucially, the evolutionary framework reminds us that natural rewards—friendship, purpose, connection—still matter. These "primary goods" (Ward & Stewart, 2003) aren’t just nice-to-haves; they’re foundational to any effective treatment strategy.
Conclusions: Toward an Evolutionary Public Health
Substance misuse, in this view, is not an aberration of human behavior—it’s an expression of it. The same brain that evolved to seek fermented fruit and celebrate group cohesion around a fire is now confronted with lab-synthesized fentanyl, sugar-dosed THC gummies, and 24-hour liquor stores. The mismatch is profound, and it's growing.
As newer and more potent substances emerge, often paired with rapid-onset delivery systems (vapes, injectables, synthetics), we must ask not just what these substances do—but why they appeal to us in the first place. The answers lie in evolutionary design.
This isn't to say addiction is inevitable. But vulnerability is. And the more we acknowledge our shared biological susceptibilities, the better we can build compassionate systems of care. An evolutionary-informed biopsychosocial model doesn’t excuse harmful behavior—it explains it. And in doing so, it offers more than judgment: it offers direction and integration.
If we’re serious about reducing harm, promoting well-being, and designing policies that actually work, then we must stop asking what’s wrong with addicts and start asking what went wrong with their environment. Evolutionary thinking may not have all the answers, but it’s a powerful place to start asking better questions.
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Very informative. I never heard anything like this in all my reading about addiction. USA is so behind in understanding addiction.