Huberman Lab Explained: How Smell, Taste & Pheromone-Like Chemicals Control You

Explore the fascinating science behind smell, taste, and the subtle chemical signals that shape our perceptions, behaviours, and even our connections with others, as revealed in the Huberman Lab podcast.

Key Takeaways

• Our sense of smell involves distinct brain pathways for innate reactions (like danger from smoke) and learned associations (like nostalgic scents).
• The simple act of inhaling through the nose significantly boosts brain alertness, attention, and memory recall compared to exhaling or mouth breathing.
• Taste perception isn't geographically mapped on the tongue; receptors for sweet, salty, bitter, sour, and umami are intermixed across its surface.
• Humans constantly engage in subconscious chemical communication, detecting signals in tears, sweat, and breath that influence hormones and behaviour.
• Taste receptors (especially for sweet and umami) are surprisingly found not only on the tongue but also in the gut and reproductive organs (testes/ovaries).
• You can actively train and enhance your sense of smell and taste through focused sniffing practices and paying close attention to flavour nuances.
• Olfactory function is a sensitive indicator of brain health, often affected by aging, neurodegenerative diseases, and traumatic brain injury.
• Genetic variations explain why individuals perceive certain smells and tastes (like cilantro or specific musks) very differently, ranging from pleasant to repulsive.
• The Maillard reaction (sugar-amino acid interaction during cooking) creates appealing savory flavours by making amino acids more detectable.

Timeline Overview

• 00:00–15:00 — Introduction, sponsor messages, vision episode recap (near-far viewing, outdoor time benefits, lutein clarification), colour vision book recommendation, overview of chemical sensing (smell, taste, human chemical signals).
• 15:00–30:00 — Mechanics of smell: sniffing, olfactory bulb location, neuron extension into mucus, three main pathways (innate danger/appetitive, learned associations, accessory/pheromone system), examples of pheromone effects in animals (Bruce, Vandenbergh).
• 30:00–45:00 — Inhalation's impact on cognition: nasal breathing boosts alertness and learning (Sobel's research), smelling salts mechanism (ammonia triggering threat response), practicing sniffing to enhance smell perception, human ability to follow scent trails.
• 45:00–01:00:00 — Olfactory neuron replenishment (neurogenesis in subventricular zone), factors influencing it (dopamine, exercise, interactions), smell loss connection to brain health (aging, TBI, Parkinson's, COVID), olfactory training for recovery, smell perception during sleep/dreams, peppermint/ammonia for arousal.
• 01:00:00–01:15:00 — Genetic basis for smell variations (microwave popcorn, cilantro, asparagus urine, musk), introduction to taste: the five/six tastes (sweet, salty, bitter, sour, umami, possibly fat), debunking the tongue map myth, the function of each taste category (energy, electrolytes, poison avoidance, amino acids, spoilage).
• 01:15:00–01:30:00 — Taste pathway (gustatory nerve, NTS, thalamus, insular cortex), taste receptor turnover/regeneration after damage (burning tongue), trainability of taste perception, animal differences in taste receptors (carnivores high umami/low sweet vs. herbivores high sweet/low umami), potential dietary influences on taste preference (keto/carnivore vs. plant-based).
• 01:30:00–01:45:00 — Taste receptors beyond the tongue: gut and gonads (testes/ovaries), links between food sensuality and reproduction, focus on sweet/umami receptors in gonads, the Maillard reaction (non-enzymatic browning, sugar-amino acid interaction), processed foods designed for texture/dopamine triggering independent of taste.
• 01:45:00–End — Miracle berry experiment (inverting sour/sweet perception), demonstrating taste perception determined at receptor level (Zuker's research), revisiting pheromones: Coolidge effect (male/female novelty response driven by odor), human pheromone debate (vomeronasal organ status), evidence for human chemical signaling (tears study, menstrual cycle shifts, partner scent recognition), sex differences in odor perception (females generally better, hormone influences), subconscious chemical sampling (handshake-eye rub study), conclusion and podcast support information.

The Intricate Mechanics of Smell: From Nose to Brain

• Smell begins with sniffing, the act of drawing volatile chemicals (odorants) into the nasal passages where they get trapped in the mucus lining. Directly above the roof of your mouth lies the olfactory bulb, a brain structure containing neurons that uniquely extend processes out through the skull (via the cribriform plate) into this mucus.
• These olfactory neurons directly detect odorant molecules. They represent one of the few neuronal populations in the human brain that are constantly replenished throughout life, dying off and being replaced by new neurons born deep within the brain (subventricular zone) roughly every few weeks.
• Signals from these neurons travel into the brain via three main pathways, explaining the diverse impacts of smell:
  • Innate Responses: One pathway connects directly to areas like the amygdala, responsible for immediate, hard-wired reactions. This triggers approach behaviours for inherently pleasant smells (like food) or avoidance/alertness for dangerous ones (like smoke or putrid odors), essential for survival.
  • Learned Associations: Another pathway links smells to memory centres (like the hippocampus). This is why specific scents can powerfully evoke strong memories and emotions tied to past experiences, such as childhood homes or particular people. Olfaction's ancient origins contribute to this strong memory link.
  • Accessory Olfactory System: While controversial in humans regarding a distinct "pheromone" organ (vomeronasal/Jacobson's organ), this pathway handles chemical signals between individuals, influencing social and reproductive behaviours, even if the exact mechanisms differ from animals with clear pheromonal responses.
• Genetic variations in olfactory receptor genes cause significant individual differences in smell perception. This explains why some people find scents like cilantro, microwave popcorn, or certain musks pleasant, while others find them intensely repulsive (e.g., smelling like soap or vomit). You literally possess different molecular detectors based on your inherited genes.
• Olfactory function is closely tied to brain health. Loss of smell (anosmia) can be an early indicator of neurodegenerative conditions like Parkinson's or Alzheimer's, and it's often affected by traumatic brain injury (TBI) due to the shearing of olfactory neuron connections at the cribriform plate during impact. Recovery of smell can partially track TBI recovery.
• Smelling salts (often ammonia-based) work by intensely activating the innate threat-detection pathway via the amygdala, causing a rapid surge in alertness and adrenaline—a powerful, albeit potentially harsh, way to jolt the system awake. Peppermint scent offers a milder alertness boost through similar, though less intense, pathway activation.

Breathing, Sniffing, and Brain Function: Enhancing Cognition

• The simple mechanical act of inhaling, particularly through the nose, has a profound and direct impact on overall brain function, independent of actually smelling anything specific. Research shows inhalation increases brain arousal, alertness, and attention levels.
• Conversely, exhaling correlates with a subtle dip in brain arousal and cognitive readiness. This cyclical link between breath phase and brain state highlights the importance of breathing patterns for mental performance.
• Consistent nasal breathing during focused tasks (reading, studying, listening) is highly beneficial for learning and memory consolidation. Studies demonstrate that restricting breathing to the nasal passages improves cognitive task performance compared to mouth breathing or mixed breathing.
• The very act of sniffing or deliberately inhaling deeply through the nose primes the brain for sensory input and enhances the sensitivity of the olfactory system itself. Practicing sniffing can sharpen your ability to detect and discriminate odors.
• You can experience this effect directly: smell an object (like an orange), then perform 10-15 deep nasal inhalations/sniffs (even of neutral air), and then smell the object again. You'll likely perceive the scent as richer and more intense due to heightened brain alertness and olfactory neuron sensitivity.
• This connection between breathing patterns and cognitive state underscores why practices emphasizing controlled nasal breathing can improve focus and mental clarity. It's a direct physiological mechanism, not just a mindfulness concept. Andrew Huberman stated: "sniffing itself is a powerful modulator of our cognition and our ability to learn."

The Science of Taste: Decoding Flavors and Preferences

• Our sense of taste relies on detecting chemicals via specialized receptors on the tongue, primarily identifying five core qualities: sweet, salty, bitter, sour, and umami (savory). A sixth taste receptor for fat is also increasingly recognized by scientists.
• The traditional "tongue map" showing specific taste zones is a myth. Taste receptors for all qualities are distributed across the tongue surface, concentrated within the grooves surrounding the small bumps (papillae), not on the bumps themselves.
• Each taste category serves a vital evolutionary purpose:
  • Sweet: Signals readily available energy sources (sugars).
  • Salty: Detects essential electrolytes (like sodium) needed for nerve and body function.
  • Bitter: Warns against potential poisons, often triggering a gag reflex.
  • Sour: Indicates spoilage or fermentation, potentially harmful substances.
  • Umami: Detects amino acids, crucial building blocks for the body, found in savory foods like meats and broths.
  • Fat: Likely signals dense energy sources and essential fatty acids.
• Taste signals travel from the tongue via the gustatory nerve to the brainstem (nucleus of the solitary tract), then relay through the thalamus to the insular cortex, where the perception of flavour is consciously processed within milliseconds.
• Remarkably, taste receptors aren't confined to the tongue. Research shows key receptors, especially for sweet (T1R2) and umami (T1R1), are also expressed in the gut and, surprisingly, in the reproductive organs (testes and ovaries), hinting at deep physiological links between nutrition, pleasure, and reproduction.
• Your specific diet can shape your taste preferences and sensitivities over time. Regularly consuming high-umami foods (like meats) may enhance sensitivity and craving for savory tastes, while a diet rich in plant-based foods might heighten sensitivity to sweetness, potentially explaining some dietary preference divides.

Beyond Smell and Taste: Chemical Signaling Between Humans

• While the existence of true, discrete pheromones in humans is debated (lacking identification of specific molecules and a consistently functional vomeronasal organ), substantial evidence confirms that humans communicate via chemical signals.
• A compelling study showed that male subjects smelling tears collected from women experiencing sadness exhibited significant reductions in testosterone levels and activity in brain areas linked to sexual arousal, demonstrating a clear chemical influence on physiology and behaviour.
• Research on menstrual cycle synchrony among cohabiting women suggests chemical signaling occurs, but rather than perfect synchrony, odors from women in different cycle phases (follicular vs. ovulatory) tend to either shorten or lengthen the cycles of those who smell them.
• Humans possess a remarkable ability to recognize familiar individuals by scent alone. Studies show individuals can reliably identify the worn t-shirt of their romantic partner from a large selection, even when the scent concentration is below conscious detection thresholds, indicating powerful subconscious olfactory processing.
• We engage in subconscious chemical sampling behaviours. Studies observed that after shaking hands with a stranger, people almost invariably touch their own face soon after, often near the eyes or nose, effectively transferring and sampling chemicals from the other person's skin onto their own mucosal surfaces. This mirrors animal behaviours like bunting (rubbing scent glands).
• These chemical signals, whether discrete pheromones or complex odor blends, likely convey information about health, hormonal status, genetic compatibility (related to immune system genes like MHC), and emotional state, influencing attraction, social bonding, and avoidance behaviours at a subconscious level.
• There are sex differences in odor perception, with studies generally indicating that females outperform males in odor detection, identification, and discrimination tasks. This sensitivity in females often fluctuates with hormonal changes across the menstrual cycle, peaking around ovulation.

Training Your Chemical Senses: Practical Tools and Applications

• Unlike some other senses, smell and taste are highly trainable. You can significantly enhance your ability to detect, discriminate, and appreciate nuances in odors and flavours through conscious practice and attention.
• Practice focused sniffing: Regularly take moments to deeply inhale and analyze the scents around you, from food ingredients while cooking to the general environment. This active engagement strengthens olfactory pathways. As discussed, even sniffing neutral air for 10-15 repetitions can temporarily heighten your olfactory sensitivity before smelling something specific.
• Pay mindful attention to taste: When eating, consciously try to identify the individual taste components – sweet, salty, sour, bitter, umami, and even fattiness. Consider the texture and how it interacts with the flavour. This focused attention refines your palate.
• Use experiments like miracle berry (miracle fruit): Consuming this natural product temporarily alters taste receptors, making sour things taste intensely sweet. Tasting familiar foods after taking miracle berry reveals the underlying contribution of sweetness or sourness to their overall flavour profile, offering a unique way to understand your own perception.
• Leverage nasal breathing for cognitive enhancement: Make a conscious effort to breathe through your nose during tasks requiring focus, learning, or memory recall. The direct link between nasal inhalation and brain alertness provides a physiological advantage.
• Olfactory training can aid recovery: For individuals experiencing smell loss (e.g., post-TBI, post-viral infection like COVID, or due to aging), systematically smelling a set of distinct odors (e.g., rose, eucalyptus, lemon, clove) daily can help stimulate olfactory neuron regeneration and improve function over time.

Olfaction, Taste, and Overall Health: Connections and Implications

• The health of your olfactory system is a surprisingly robust indicator of overall neurological health. A decline in the sense of smell can be an early warning sign for neurodegenerative diseases such as Parkinson's and Alzheimer's, sometimes appearing years before motor or cognitive symptoms manifest.
• Traumatic Brain Injury (TBI) frequently causes smell dysfunction (anosmia or hyposmia) because the impact can sever the delicate olfactory neuron fibers passing through the cribriform plate at the base of the skull. Monitoring the recovery of smell can be one marker for tracking TBI rehabilitation progress.
• Olfactory neurons are unique in their capacity for lifelong replenishment (neurogenesis) from stem cells in the subventricular zone. Factors like dopamine levels, social interaction, and exposure to varied odors appear to support this process, suggesting that staying engaged with your olfactory environment might help maintain the system's health.
• Taste perception is intrinsically linked to nutritional choices and metabolic health. The innate drive towards sweet (energy), salty (electrolytes), umami, and fat (essential nutrients) guides intake, while aversion to bitter and sour protects against toxins and spoilage. Dysregulation in these systems can contribute to unhealthy eating patterns.
• The presence of taste receptors in the gut and on reproductive organs underscores the deep integration of chemical sensing with digestion, metabolism, and even reproductive physiology, going far beyond simple flavour perception on the tongue.
• Understanding the power of chemical senses highlights their role not just in survival (finding food, avoiding danger) but also in shaping our social interactions, emotional responses, memory, and overall quality of life through the richness they add to our experiences.

Bottom Line

Our senses of smell and taste are far more powerful and dynamic than often realized, deeply influencing our brain function, health, and social connections through intricate chemical detection systems. Engaging with and actively training these senses can enhance cognitive abilities, enrich our experiences, and potentially offer insights into our neurological well-being.