Addiction and the animal kingdom

In the wild, survival instincts reign supreme. Each species in the animal kingdom follows its natural rhythms to eat, mate, and thrive. But beneath these primal behaviours lies a surprising truth: animals, just like humans, can develop behaviours that resemble addiction. Whether it’s wallabies indulging in poppy fields or dolphins getting high on puffer fish toxins, the natural world offers a fascinating glimpse into the universal pull of addiction. As we explore these strange animal habits, it begs the questions: what can nature’s creatures teach us about our own struggles with substance use?

What is addiction?

Addiction is an extremely broad conceptual field, but if we were to define it broadly, we would call it a compulsive need to engage in a behaviour or consume a substance regardless of any consequence that may arise as a result of repeatedly doing so. It begins with dependency, which is brought about by tolerance to a substance or behaviour (needing more of it to achieve the same effect) and is also later met with withdrawal symptoms when not using the substance. Humans and animals can both exhibit these key addiction symptoms.

In the animal kingdom, behaviours resembling addiction have been observed, particularly in studies involving drug or alcohol exposure. For instance, animals like rats, monkeys, and even fruit flies have been shown to compulsively seek out substances like cocaine or alcohol, even when it leads to harmful outcomes like physical deterioration or increased vulnerability to predators. Studies have been performed on rats, indicating that they develop dependencies on drugs like cocaine when they are isolated from other rats.

Addiction in animals: examples

Addiction-like tendencies in animals are prevalent in a range of species and is a fascinating field of study, often used in research to understand human addiction. Many animal studies have provided insight into how addiction develops, behaviours associated with it, and the role of the brian’s reward system.

Below are some examples of addiction observed in various animals:

Primates: Primates, such as monkeys, have shown they can develop a preference for alcohol. Specifically rhesus macaques have been observed drinking ethanol solutions. Similar to humans, some would drink in moderation and other monkeys would drink until visibly impaired, stumbling and falling—behaviour strikingly similar to human alcohol addiction. Monkeys have also been known to develop a strong preference for sugary substances, which can be another form of addiction.

Rodents: In laboratory settings, rodents like rats and mice are commonly used to study addiction, most famously in the 1970s “Rat Park” experiment. These animals quickly develop dependencies on substances such as cocaine, heroin, and nicotine. They often press levers repeatedly to self-administer drugs, sometimes to the point of neglecting food and water, which leads to severe health decline or even death. Additionally, they may experience withdrawal symptoms, including depression and anxiety.

Bees: Bees have been shown to develop a preference for caffeine-laden nectar, as some plants naturally produce caffeine, which enhances bees memory of the plant’s location and encourages them to return. This dependency-like behaviour suggests the impact caffeine has on reward pathways in animals as small as insects.

Elephants: These majestic animals are known to consume fermented fruits, mainly narula fruit. There’s plenty of debate about whether or not elephants are actually capable of becoming intoxicated, but there is some evidence to suggest that the tusked beasts actively seek out and consume large amounts of this fruit, with the aim of becoming intoxicated.

Dolphins: These intelligent marine mammals have been observed deliberately interacting with toxic pufferfish, using them to induce a narcotic-like state, mirroring the way a human seeks out their next high in the height of their addiction.

Pigeons: Some studies have found that pigeons, when given the option to choose between guaranteed food rewards and the chance for a larger reward with a higher risk, will often opt for the uncertain option, mirroring human gambling behaviour. This suggests that the urge for reward-seeking in the face of risk is not unique to humans.

The science behind animal addiction

Addiction in humans and animals is not a dissimilar phenomenon, because we share common neurological and biological mechanisms. The brain’s rewarding system in humans and animals is the same, primarily driven by dopamine. It motivates animals to pursue pleasurable activities such as eating for the sake of eating or, in cases of addiction, the consumption of drugs or alcohol.

Additionally, the neurotransmitters serotonin and GABA are also present in animals. Serotonin is associated with mood regulation, and disruptions in serotonin levels can worsen compulsive behaviours, including those related to substance use. GABA, which inhibits neurotransmission, is often diminished during addiction, leading to heightened anxiety or cravings when an animal is deprived of its addictive substance.

Evolutionary perspectives

These behaviours in animals have evolutionary roots in survival mechanisms. The brain’s reward system, particularly driven by dopamine, evolved to motivate essential behaviours like seeking food or mates, which enhanced survival and reproductive success. Over time, this system has been co-opted in both animals and humans for more maladaptive behaviours, like substance abuse, when certain environments make addictive substances easily accessible.

What animals teach us

Since our brains operate similarly, scientists use animal brains as models for experiments to better understand human compulsive behaviour. These models, which simulate the human addiction process, reveal how substances like drugs can hijack the brain’s reward system, causing animals to display behaviours that closely mimic human addiction, including:

• Craving
• Dependency
• Withdrawal

Animal studies have been so effective in the development of addiction treatments. Researchers use these models to test the efficacy of new medications and behavioural therapies before human trials.

Studying addiction in animals has significantly advanced our knowledge of human addiction, guiding the development of new treatments and therapies. These findings emphasise the importance of animal research in addressing drug addiction, withdrawal, and relapse.