The Curious Case of Catnip. Why Do Cats Go Crazy But Humans Stay Sane?

Catnip is a fragrant herb from the mint family that has a unique effect on domestic cats. When cats come into contact with or ingest catnip, it can cause a temporary sense of euphoria, stimulation, and playfulness. While approximately 80% of domestic cats are susceptible to catnip’s effects, it strangely does not impact humans and other animals in the same way. This provokes an interesting question – why does catnip elicit such a strong reaction in cats, but not humans? In this article, we will explore the science behind catnip’s effects on cats versus humans.

What is Catnip?

Catnip—also known by its scientific name Nepeta cataria—is a member of the mint family. The active compound in catnip is called nepetalactone. This chemical is concentrated in the leaves and stems of the catnip plant. Catnip contains about 0.3–1.4% essential oil by weight, and the main component of the essential oil is nepetalactone at 40–90%.

Sources:

https://www.marthastewart.com/2140307/what-is-catnip

https://www.petmd.com/cat/general-health/what-is-catnip

Catnip’s Effects on Cats

Catnip has an intense and euphoric effect on most cats. When cats sniff, eat or rub against catnip, the nepetalactone in the plant binds to receptors in the cat’s olfactory tissue which activates their “reward system” similar to how opioids work in humans.

The effect of catnip can last 5-15 minutes [1]. Exposure induces a state of frenzy in cats characterized by specific behaviors like rolling, flipping, rubbing, and chasing imaginary objects. They may also drool, groom excessively, vocalize, or become uncharacteristically playful and affectionate. The effects vary from stimulatory to mildly sedating which is known as the “catnip response.” Not all cats respond to catnip, as the reaction is an estimated 50-50 split in domestic cats.[2]

Why Catnip Affects Cats

The active ingredient in catnip that causes euphoric effects in cats is called nepetalactone. This is an organic compound that binds to olfactory receptors in a cat’s nose and stimulates a response from the olfactory bulb, which is the part of the brain responsible for processing smells.

cat sniffing catnip plant

When nepetalactone enters a cat’s nasal passage and binds to these olfactory receptors, it triggers a neurological response that is akin to a euphoric high for cats. Nepetalactone is structurally similar to feline pheromones and acts as a stimulant when inhaled. The olfactory bulb sends signals to the amygdala and hypothalamus in the brain, inducing both euphoric and hyperactive behavior in cats.

Cats also have an organ called the vomeronasal or Jacobson’s organ located in the roof of their mouths that detects pheromones. Some researchers believe this organ may also play a role in detecting nepetalactone and initiating the neurological pleasure response in cats when they smell and ingest catnip.

The key factor that causes catnip to affect cats but not humans is the molecular structure of nepetalactone and how it binds to feline olfactory and vomeronasal receptors. The receptors in a cat’s nose and sensory organs are specifically sensitive to this unique compound in a way that human receptors are not.

Cat vs Human Olfaction

Cats have a much more powerful sense of smell compared to humans. Cats have over 200 million odor receptors in their noses, while humans only have around 5 million (Paws Chicago, 2022). This means cats have a sense of smell that is approximately 14 times stronger than humans (Rover, 2023).

The feline nose contains a vomeronasal organ that detects pheromones, allowing cats to gather chemical signals related to territories and mating. Cats also have a large surface area of olfactory epithelium in their noses to detect smells. Their brains also devote a large area to analyzing olfactory information (Zhang et al., 2022).

In contrast, the human sense of smell is relatively weak. Humans have far fewer odor receptors and lack specialized structures like the vomeronasal organ. While cats rely heavily on their sense of smell to understand their environment, humans depend more on vision and hearing.

Nepetalactone Interaction in Humans

Nepetalactone is the main chemical compound in catnip that causes a response in cats. However, this compound does not have the same effect in humans due to differences in our olfactory systems.

human smelling catnip

The human nose has about 5 million olfactory receptor neurons, compared to a cat’s nose which has around 200 million. This gives cats a far superior sense of smell and allows them to detect compounds like nepetalactone at very low concentrations. Nepetalactone binds to receptors in a cat’s olfactory epithelium, sending signals to the brain that trigger a response. But the human nose lacks the specific receptors that nepetalactone binds to in cats.

Furthermore, the structure of the human olfactory bulb is less complex compared to cats. Processing scent signals from nepetalactone simply does not induce any behavioral effects in humans as it does for felines. While humans can detect the smell of catnip, the nepetalactone does not stimulate any reward response or trigger instincts and behaviors the way it does in cats. So instead of getting giddy and playful, we just register it as a pleasant herbal or minty aroma.

In summary, nepetalactone interacts with the human nose on a purely olfactory level but does not generate the same neurochemical reactions and instinctive responses that explain catnip’s effects on cats.

[Source 1]

Other Chemical Differences

In addition to differences in olfaction, cats and humans have other neurological differences that likely contribute to the varying response to nepetalactone. Cats possess a vomeronasal organ, which detects pheromones and triggers behavioral responses. Humans lack this organ. Additionally, cats have a high density of olfactory epithelium compared to humans, allowing them to better detect certain odors like nepetalactone. At the neurological level, cats may have more olfactory receptor neurons or differences in olfactory processing pathways that make them especially sensitive to catnip (1).

Research also shows cats have more bitter taste receptors than humans, specifically for detecting bitter alkaloids like nepetalactone (2). While humans cannot taste nepetalactone, cats likely have a strong bitter taste response that drives their attraction. Overall, cats are evolutionarily adapted to detect and behaviorally respond to compounds like nepetalactone at much lower concentrations than humans.

(1) https://pubmed.ncbi.nlm.nih.gov/36008824/

(2) https://link.springer.com/article/10.1007/BF00987747

Alternative Explanations

There are a few other hypotheses for why catnip affects cats but not humans:

One is that the response to catnip is conditioned or learned in cats. Kittens do not react to catnip until they are around 6 months old, suggesting there may be a learned component. Cats may react to catnip because they have learned to associate it with pleasurable sensations through exposure at a young age.

Another theory is that catnip triggers a predatory response in cats. The rolling, cheek rubbing, and crazy playing exhibited after exposure to catnip mirrors a cat’s pre-hunting rituals. Catnip may tap into an innate hunting instinct cats possess. Humans do not have the same instinctual drive, which could explain why we do not react in the same way.

cat rolling around after smelling catnip

A third idea is that catnip simply causes sensory stimulation for cats, but not humans. The volatile oils in catnip trigger cats’ Jacobson’s organ and olfactory system. This creates an intense sensory experience that humans lack. So even though humans can detect the smell of catnip, we do not process it in a way that creates euphoria.

While the true reason is still being studied, these alternative hypotheses suggest there may be multiple factors involved in catnip’s strange effects on cats.

Sources:

[Why Doesn’t Catnip Work on Humans?](https://www.reddit.com/r/NoStupidQuestions/comments/16vgq6p/why_doesnt_catnip_affect_humans/)

Catnip Effects on Other Species

While catnip is most known for its effects on domestic cats, it can also influence the behavior of other feline species. Big cats like lions, tigers, leopards, and jaguars have all demonstrated responses to catnip similar to domestic cats. When exposed to catnip, big cats may rub against it, roll around, and playfully interact with the plant. However, the reaction seems to be much less consistent and intense compared to domestic cats.

This is likely because catnip has evolved to specifically influence the behavior of smaller feline species for its own reproductive benefit. The volatile oils in catnip mimic feline pheromones that provoke a response geared toward spreading the plant’s seeds. As big cats are not the natural carriers of catnip seeds, they have less sensitivity to the active chemical compounds.

Outside of the feline family, catnip does not appear to have major effects on the behavior of other mammals like canines, rodents, or humans. The key ingredients that cause a reaction in cats are not present in the olfactory systems of most other species.

Conclusion

cat and human faces side by side

In summary, catnip contains a chemical compound called nepetalactone which binds to receptors in a cat’s nose and induces a euphoric state. However, humans lack the same receptors that allow nepetalactone to have this psychoactive effect on cats.

The reason for this difference has to do with variations in olfactory systems across species. A cat’s nose contains an organ called the vomeronasal organ which detects pheromones and triggers the euphoric response to nepetalactone. Humans, however, do not have a functional vomeronasal organ.

Additional differences between cat and human nervous systems, genetics, and brain structure contribute to cats’ sensitivity to catnip compared to humans. While some anecdotal reports suggest catnip may have a mild sedative effect in humans when consumed as a tea, the main psychoactive substance largely only affects cats.

In conclusion, catnip triggers a unique euphoric reaction in domestic cats but not humans due to differences in our olfactory systems and neurology. The vomeronasal organ allows nepetalactone to induce behavioral changes in cats, while humans lack this organ and the ability to experience catnip’s effects to the same degree.

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