It may seem like an odd question: why do we perceive foods as having specific tastes? In this article, we explore the evolutionary reasons behind humans' ability to detect the five basic tastes and examine how these sensory capabilities have developed. Additionally, we consider how the food industry exploits our biochemical pathways to encourage overconsumption

When it comes to foods it’s not a stretch to suggest that in the privileged position of having enough we humans generally consume too much of the wrong things but the reasons why are complicated.

Lets start with the sense of taste and look at how it relates to our evolutionary biology.

Humans experience five primary taste sensations: sweet, salty, sour, bitter, and umami. Each of these taste sensations plays a crucial role in evolutionary biology, helping our ancestors identify nutritious foods, avoid toxins, and maintain electrolyte balance. We will look at these one by one and consider their evolutionary significance and how these triggers are use by the processed food industry to get you to consume more than you need.

SWEET

How Sweet Taste is Detected:

The sensation of sweet taste is detected through specialised taste receptor cells located primarily on the tongue.

Taste buds, the sensory organs responsible for detecting taste, are primarily located on the papillae of the tongue, but can also be found on the soft palate, the upper oesophagus, the cheek, and the epiglottis. Each taste bud contains 50-100 taste receptor cells. The sweet taste is detected by specific receptor proteins on the surface of taste receptor cells within the taste buds. The main receptors for sweet taste are part of the G-protein coupled receptor family, specifically the T1R2 and T1R3 receptor subunits. These subunits combine to form a functional sweet receptor.

When sweet molecules (such as sugars and artificial sweeteners) bind to the T1R2/T1R3 receptors, they trigger a signal transduction pathway. This involves the activation of a G-protein called gustducin, leading to a series of intracellular reactions that result in the release of neurotransmitters. The neurotransmitters stimulate the gustatory nerve fibres, sending signals to the brain. The signals travel through the cranial nerves (primarily the facial nerve VII and glossopharyngeal nerve IX) to the gustatory cortex in the brain, where the sweet taste is perceived.

Role of Sweet Taste in Human Development

Sweet taste signals the presence of sugars and carbohydrates, which are vital sources of energy. In ancient environments where food sources were unpredictable, a preference for sweet foods ensured adequate caloric intake. Early humans who could identify and consume sweet foods had a better chance of survival and reproductive success.

Many sweet-tasting foods, such as fruits, are not only rich in sugars but also provide essential vitamins, minerals, and fibre. The preference for sweet-tasting fruits would have encouraged the consumption of nutrient-dense foods, supporting overall health and development. Also, for civilisations away from the tropics with the exception of honey ‘sweet’ would only be available to us in the fruiting summer season when wild berries, soft fruits and tree fruits were available.

The human preference for sweet foods influenced the domestication and cultivation of sweet-tasting plants, such as fruits and tubers. This preference played a significant role in the development of agriculture, leading to the establishment of stable food sources and the advancement of human civilisations and it is worth noting that as we have domesticated these plantsw for agriculture we have significantly deliberately increased their sweetness by selectively breeding for increased sugar content.

Modern Implications:

The innate preference for sweet taste persists in modern humans, influencing dietary choices and food consumption patterns. This preference can sometimes lead to overconsumption of sugary foods, contributing to health issues such as obesity, diabetes, and dental problems, our biology has not caught up with this over abundance of sweet tasting foods and we’re simply hard wired to crave them so how can we re calibrate our senses?

The simple way to recalibrate your taste is abstinence. Repeated exposure to sweet foods can diminish our taste perception of sweetness over time. This phenomenon, often referred to as "taste adaptation" or "taste habituation," occurs when our taste buds and sensory perception become less sensitive to a particular taste stimulus.

If complete abstinence isn’t an option for you then cutting back and reducing the sweetness of foods will over time lead you to find foods once craved to be unbearably sweet and can even lead to foods such as carrots and apples that perhaps you didn’t even register as sweet to be satisfying.

SALT

Unlike ‘sweet’, salt is absolutely essential for life so the reason we can taste it is more fundamental than perhaps tasting sugars.

Salt as we think of it is the chemical Sodium Chloride (NaCl) but our taste receptors can also detect a salty taste from Potassium Chloride (KCl), Lithium Chloride (LiCl) and to a lesser degree and with a little bitterness Calcium Chloride (CaCl2)

How do we taste salt?

Salty taste is detected by taste receptor cells within the taste buds, primarily located on the tongue. The primary receptors involved in salty taste detection are epithelial sodium channels (ENaCs). These channels are directly activated by the presence of sodium ions.

When sodium ions enter the taste receptor cells through ENaCs, they cause depolarisation of the cell membrane. This depolarisation triggers the release of neurotransmitters that send signals to the brain via the gustatory nerves, leading to the perception of saltiness.

Neural Pathways:

The gustatory signals are transmitted through cranial nerves, primarily the facial nerve (VII) and glossopharyngeal nerve (IX), to the brain. The signals reach the gustatory cortex in the brain, where the sensation of saltiness is perceived and interpreted.

As a flavour enhancer

Salt is said to enhance other flavours due to its unique ability to modify and amplify taste perception through several scientific mechanisms. Firstly, salt balances sweetness and acidity in foods. It can reduce the bitterness in certain ingredients, thereby making sweet flavours more pronounced. This is why a pinch of salt is often added to baked goods, chocolate, or caramel to enhance their sweetness. Similarly, salt can balance the acidity in dishes, such as those containing tomatoes, citrus, or vinegar, enhancing the overall taste profile.

Another key role of salt is its capacity to suppress bitterness. By doing so, it makes other tastes in a dish more noticeable and pleasant. This suppression of bitterness is particularly useful in improving the palatability of bitter vegetables like kale or Brussels sprouts.

Salt also enhances aromas, which are crucial to the perception of taste. The presence of salt can increase the release of aroma molecules in food, which are detected by the olfactory receptors in the nose, contributing significantly to the overall flavour experience.

Moreover, salt stimulates saliva production, which aids in dissolving food particles and distributing them across the taste buds. This increased salivation enhances the distribution of flavours, allowing for a more intense and enjoyable taste perception.

On a molecular level, salt can alter the way flavour compounds interact with taste receptors on the tongue. Sodium ions, in particular, can intensify certain flavours by changing the electrical charge and interaction of molecules with taste buds.

Why is salt so important?

Sodium is crucial for maintaining electrolyte balance, nerve function, and muscle contractions, in environments where sodium was scarce, a preference for salty foods provided a survival advantage by guiding individuals to consume essential electrolytes. In some places, away from the sea which was an obvious source of salt, it was hard to come by and as it becasme used to not just flvour but preserve foods it became even more valuable, in fact the etymology of the word ‘salary’ is derived from the value os salt.

The word 'salary' has its origins in the Latin word "salarium," which refers to the payments made to Roman soldiers for the purchase of salt. Salt was a critical commodity in ancient times, not only for its role in food preservation and flavouring but also for its necessity in human physiology. The value of salt was so high that it became a form of currency and payment. Over time, the term "salarium" evolved into the word 'salary,' reflecting the importance of salt in trade and daily life. This etymology highlights the integral role that salt has played in human history, influencing economic systems, dietary practices, and cultural development.

When is enough too much?

Just as salt is necessary for human life too much can over time cause problems and inbalances. Excessive salt intake is linked to high blood pressure as it simply increases the amount of fluid in the blood vessels, this in turn causes the heart to have to work harder and has implications for heart disease. Also, high salt levels in the urine can lead to kidney stones and this can impair their ability to filter waste from the blood.

High salt intake has been linked to an increased risk of stomach cancer. Salt may damage the stomach lining and promote the growth of Helicobacter pylori, a bacterium associated with stomach ulcers and cancer.

Altered Taste Sensitivity: Overconsumption of salt can desensitize taste buds, making it harder to appreciate the natural flavors of foods. This can lead to a preference for saltier foods and a cycle of excessive salt intake.

How to reset your salt perception?

It should be obvious as to why we crave salt from an evolutionary biological perspective but we are now living in a time of plenty not scarcity so a recalibration is often required so that we can trust our cravings for salt to take in the correct amount rather than an excess. Patients who have been instructed to severely reduce their salt intake often report finding mildly seasoned foods to be overwhelmingly salty on reintroduction, just as with sugar once the baseline is reset we become more capable of naturally regulating to a healthy sodium intake.

SOUR

The taste of sour is a curious one, one one hand it’s relatively simple to explain and to describe as it’s simply defined by a low Ph or by a substance being acidic. The detection of sour taste is a complex biological process involving specialised taste receptor cells located within the taste buds on the tongue and other areas of the mouth. These receptors are particularly responsive to acids, which release hydrogen ions (protons) when consumed. The key players in this process are proton-sensitive ion channels, notably acid-sensing ion channels (ASICs) and potassium (K+) channels.

When acids in food release hydrogen ions into the saliva, these ions enter the taste receptor cells through the proton-sensitive channels. This influx of protons causes depolarisation of the cell membrane—a change in electrical charge that triggers the release of neurotransmitters. These neurotransmitters then activate nerve fibers connected to the taste receptor cells, sending signals to the brain.

The signals travel via the gustatory nerves, particularly the facial nerve (cranial nerve VII) and glossopharyngeal nerve (cranial nerve IX), to the brainstem. From there, they are relayed to the thalamus and ultimately to the gustatory cortex, the brain region responsible for processing taste. In the gustatory cortex, these signals are interpreted as the sensation of sourness.

The interesting part however is that sour can ilicit various responses as from pleasure to aversion depending on circumstance.

Under ripe or overripe?

Most of the acidic or sour-tasting foods we consume are fruits, which have coevolved with animals to be appealing when their seeds are fully mature. Typically, fruits are naturally designed to be sweet and ripe when their seeds are capable of producing a new plant. This evolutionary strategy encourages animals to eat the fruit and disperse the seeds, aiding in the plant’s reproduction.

Before the seeds are sufficiently developed to survive passage through a digestive system and be deposited—ideally with a beneficial amount of organic manure away from the parent plant—fruits are often very sour. This sourness discourages animals from eating the fruit when it offers no reproductive advantage to the plant.

Interestingly, as fruits pass their peak ripeness and begin to decay, the microbial breakdown of sugars often creates a sourness that is unpalatable to us, with a few exceptions, such as when we have deliberately manipulated and encouraged the transformation through controlled fermentation.

Overriding the natural aversion to sour

Us humans have indeed learned to appreciate certain sour tastes, even overcoming our evolutionary aversion to this flavour, largely due to the controlled use of fermentation in making foods and beverages such as alcohol, yogurt, sauerkraut, kimchi, and sourdough bread. This shift in taste preference is a result of cultural practices, acquired tastes, and the recognition of the benefits associated with fermented foods

Over time, many cultures have developed fermentation techniques that produce sour flavours in foods and drinks. Controlled fermentation involves the use of specific bacteria, yeasts, or fungi to convert sugars into acids, alcohol, or other compounds, resulting in distinctive sour tastes. Examples include the lactic acid fermentation in yogurt and sauerkraut or the acetic acid fermentation in vinegar and kombucha.

Fermented foods often have enhanced nutritional value, including increased levels of vitamins, probiotics, and beneficial enzymes. For example, the fermentation of milk into yogurt not only introduces a pleasant tangy flavour but also makes the product easier to digest and improves gut health. Recognising these benefits, humans have developed a preference for the sour tastes associated with fermented foods.

The preference for sour flavours in fermented foods is also a matter of acquired taste. While the initial reaction to sourness may be aversion due to its association with spoilage or unripe foods, repeated exposure to sour-tasting fermented foods can lead to an appreciation of these flavours. Over generations, certain sour foods and beverages have become integral parts of various culinary traditions, making them more accepted and even desirable.

BITTER

Physiological Mechanisms of Bitter Taste Perception

The human ability to taste bitter is a complex physiological process that involves specialized receptors on the tongue and a specific signal transduction pathway. Bitter taste is primarily detected by a group of taste receptor proteins known as T2R receptors, which are part of the G-protein-coupled receptor (GPCR) family.

Taste Receptors and Taste Buds: Bitter taste is detected by taste receptor cells located within the taste buds, primarily on the tongue but also on other areas of the mouth and throat. These taste buds contain a variety of taste receptor cells, each responsive to different taste modalities, including bitter.

T2R Receptors: The detection of bitter compounds is facilitated by T2R receptors. There are about 25 different types of T2R receptors, each capable of recognizing a variety of bitter substances. This diversity of receptors allows humans to detect a wide range of bitter compounds, many of which are structurally different from one another.

Signal Transduction Pathway: When a bitter substance binds to a T2R receptor on the taste receptor cell, it activates a G-protein called gustducin. Gustducin initiates a signal transduction cascade that ultimately leads to the release of calcium ions within the cell. This increase in intracellular calcium triggers the release of neurotransmitters, which then activate the nerve fibers connected to the taste receptor cells.

Neural Processing: The signals generated by the activation of T2R receptors are transmitted via the gustatory nerves, particularly the glossopharyngeal nerve (cranial nerve IX) and the vagus nerve (cranial nerve X), to the brainstem. From there, the signals are relayed to the thalamus and then to the gustatory cortex, where the sensation of bitterness is perceived. This neural pathway allows the brain to recognize and respond to the bitter taste, often triggering an aversive reaction.

Evolutionary Role of Bitter Taste

Toxin Detection and Avoidance: The primary evolutionary role of the ability to taste bitter is to detect and avoid potentially harmful substances. Many naturally occurring toxins, such as alkaloids and other plant defense compounds, taste bitter. Early humans who could detect bitter tastes were more likely to avoid consuming toxic plants, leading to a survival advantage. This protective mechanism has been crucial in preventing poisoning and illness.

Genetic Variation in Bitter Taste Perception: There is significant genetic variation in the human population regarding the sensitivity to bitter tastes. Some people, known as "supertasters," have a heightened sensitivity to bitter compounds due to a higher density of taste buds and more sensitive T2R receptors. Others may be less sensitive, allowing them to tolerate or even enjoy foods with a strong bitter taste. This variation likely evolved as a balance between the need to avoid toxins and the need to consume a diverse diet, which sometimes includes bitter but beneficial compounds.

The paradox of bitter

Bitterness has a complex and intriguing relationship with appetite, which explains why bitter foods and beverages are often served before a meal as appetisers or aperitifs. When we consume something bitter, it stimulates the production of digestive enzymes and saliva, both of which are essential for digestion. The bitter taste triggers a reflex that increases salivation, helping to lubricate food and prepare it for digestion, while also activating the production of gastric juices in the stomach. This rise in digestive fluids primes the body to process food, thereby stimulating the appetite.

Bitter tastes also activate the vagus nerve, which plays a crucial role in regulating the digestive system. When stimulated, the vagus nerve enhances the release of digestive secretions, such as bile and pancreatic enzymes, which are necessary for breaking down food. This activation signals the body that food is about to enter the digestive system, heightening the sense of hunger and preparing the stomach for the meal ahead.

Cultural practices have long recognised the appetite-stimulating effects of bitterness. Aperitifs, often in the form of bitter liqueurs or beverages, are traditionally consumed before meals to awaken the appetite. Similarly, bitter appetisers, such as salads made with bitter greens like rocket or radicchio, serve to stimulate digestion and create a pleasant anticipation of the meal. These foods and drinks not only prepare the digestive system but also cleanse the palate, making the flavours of the subsequent dishes more pronounced and enjoyable.

There is also a psychological element to the way bitterness stimulates appetite. The initial sharpness or pungency of a bitter taste can create a mild sense of alertness, which paradoxically heightens the desire for something more soothing or satisfying—typically the main meal. This response primes both the body and mind for the meal, enhancing the overall dining experience.

UMAMI

Umami, the 5th taste is where things get even weirder as the ability to sense this taste is hard wired into our biology but we only recognised it as separate from the other four tastes as recently as 1908!

It was first scientifically identified in 1908 by Kikunae Ikeda, a chemist and professor at Tokyo Imperial University. While studying the unique flavour of kombu dashi, a traditional Japanese broth made from kombu seaweed, Ikeda observed that its taste was distinctly different from the four basic tastes of sweet, sour, bitter, and salty. He was intrigued by this savoury, mouth-watering quality that could not be classified within the existing categories of taste.

Through careful experimentation and analysis, Ikeda discovered that the key component responsible for this unique flavour was glutamate, a naturally occurring amino acid found in high concentrations in kombu. He recognised that glutamate, when combined with other ingredients, enhanced the overall palatability of foods, giving them a rich, savoury depth that was previously unrecognised in the scientific study of taste.

Ikeda named this distinct taste "umami," derived from the Japanese words "umai," meaning "delicious," and "mi," meaning "taste" or "essence." This discovery not only expanded our understanding of taste but also laid the foundation for the widespread use of monosodium glutamate (MSG) as a flavour enhancer in culinary practices around the world.

A student of Japanese cuisine will appreciate the importance of layering umami-rich ingredients and understand how bases like dashi, as mentioned earlier, enhance the overall palatability of dishes. However, this approach is not unique to Japanese cooking. While umami might not have been officially recognised until recently, it is equally abundant in other cuisines, such as Italian. In Italian cooking, glutamate-rich ingredients like cooked or dried tomatoes, anchovies, Parmesan cheese, cured meats, and mushrooms are highly valued for the depth of flavour they bring and their ability to elevate other tastes in a dish.

The evolutionary advantage of umami detection

The capacity to detect umami would have been advantageous for early humans, guiding them toward protein-dense foods that were vital for growth, tissue repair, and overall health. Foods rich in umami often contain amino acids like glutamate, which are the building blocks of proteins necessary for numerous bodily functions. By recognising and seeking out umami-rich foods, our ancestors were able to ensure an adequate intake of essential nutrients, contributing to their survival and reproductive success.

The role of umami in human diet extends beyond mere flavour; it is intricately linked to satiety and digestion. Foods that are rich in umami tend to promote a sense of fullness, which is beneficial for regulating food intake. Additionally, umami can enhance the palatability of foods, making them more enjoyable to eat, which in turn encourages the consumption of protein-rich diets. This is particularly significant in times of scarcity, where the efficient intake of necessary nutrients is critical.

Furthermore, umami has a synergistic effect when combined with other tastes, particularly sweet and salty. This ability to enhance and balance flavours makes umami a key component in various culinary traditions around the world, even in cultures that were unaware of its scientific basis until recently.

The physiology

Physiologically, the detection of umami occurs through specific receptors on the tongue and in other parts of the oral cavity. These receptors, known as T1R1 and T1R3, are G-protein-coupled receptors that bind to glutamate and other umami-related compounds, such as inosinate (found in meats) and guanylate (found in mushrooms). When these compounds interact with the receptors, they trigger a cascade of cellular events that lead to the perception of the umami taste.

Once glutamate binds to the T1R1 and T1R3 receptors, it activates a G-protein, which then initiates a signal transduction pathway. This pathway results in the release of neurotransmitters that send signals to the brain via the gustatory nerves, including the facial nerve (cranial nerve VII) and the glossopharyngeal nerve (cranial nerve IX). These signals are processed in the brain’s gustatory cortex, where they are interpreted as the savoury, satisfying taste of umami.

THE COMBINATIONS

The human experience of taste is a fascinating interplay of biology, culture, and perception, where the five basic flavours—sweet, salty, sour, bitter, and umami—combine to create an infinite spectrum of tastes. This infinite variety is made possible by the complex interactions between these flavours, the context in which they are consumed, and the individual's unique sensory and psychological framework.

Scientifically, taste is rooted in the activation of specific receptors on our taste buds, each attuned to detect one of the five fundamental flavours. When we eat, these receptors respond to the chemical compounds in food, sending signals to the brain where these inputs are processed and interpreted. However, the beauty of taste lies in the fact that it is rarely the result of a single flavour. Instead, what we perceive as taste is usually a combination of multiple flavours, layered and intertwined in complex ways.

The infinite possibilities of taste arise from the countless ways these five flavours can be combined and modified by factors such as aroma, texture, temperature, and even visual cues. The brain integrates all these sensory inputs to create a unified taste experience, which can vary widely even with slight changes in the balance of flavours.

PROCESSED FOODS

The processed food industry has mastered the art of manipulating the five basic tastes—sweet, salty, sour, bitter, and umami—to create products that are not only highly palatable but also engineered to encourage overconsumption. This manipulation taps into our biological instincts and psychological tendencies, creating a cycle where the natural signals of satiety are bypassed, leading us to eat more than we need.

Our bodies are wired to seek out certain tastes because they are associated with essential nutrients. Sweetness signals energy in the form of sugars, salt indicates the presence of vital electrolytes, and umami points to protein-rich foods necessary for growth and repair. Sourness can signal ripeness or spoilage, and bitterness often warns us of toxins. In nature, these tastes guide us toward balanced nutrition and help regulate our intake to match our physiological needs.

However, the processed food industry has found ways to exploit these natural preferences by creating foods that are hyper-palatable. These foods often contain combinations of the five basic tastes that are far more intense than what is found in nature. For example, the sweetness in processed foods is often amplified by the addition of refined sugars or artificial sweeteners, while salt levels are increased to enhance flavour and prolong shelf life. Umami, often enhanced through the addition of monosodium glutamate (MSG) or other flavour enhancers, is used to make foods irresistibly savoury.

This manipulation can be seen as a deliberate subversion of the natural balance that our bodies strive to maintain. In a natural setting, the flavours we encounter in food are in harmony with the nutrients those foods provide, and our bodies respond with appropriate signals of hunger or satiety. When these tastes are artificially amplified and combined in processed foods, they create a sensory experience that our brains interpret as overwhelmingly rewarding, even if the nutritional content of the food is poor.

This sensory overload effectively short-circuits the brain’s natural mechanisms for regulating appetite. The intense flavours mask the lack of real nutritional value, leading to what is known as "sensory-specific satiety"—the phenomenon where the brain becomes desensitised to the specific flavours but continues to crave more food, leading to overconsumption. Moreover, the balance of fats, sugars, and salts in processed foods is often designed to be "just right" to trigger the release of dopamine, the brain’s reward chemical, which reinforces the desire to eat more.

***This flavour combination does not exist in nature and confuses our evolutionary taste sensations***

This can be seen as an exploitation of human vulnerabilities—our evolutionary drives are hijacked by an industry more interested in profit than in the well-being of individuals. The pleasure derived from eating these foods becomes disconnected from the actual nourishment they provide, leading to a cycle of craving and consumption that can be difficult to break. This not only affects physical health, contributing to obesity and related diseases, but also impacts our psychological relationship with food, fostering a dependence on artificially engineered tastes.

In essence, the processed food industry’s manipulation of the five tastes is both a scientific feat and a philosophical dilemma. By creating foods that are designed to override natural satiety signals, the industry encourages a pattern of overconsumption that is at odds with our biological needs. This raises important ethical questions about the role of food manufacturers in shaping public health and the responsibility they bear for the consequences of their products. The challenge, then, is to find a way to restore balance—to reconnect with the natural harmony of tastes and nutrition that our bodies were designed to follow, and to resist the seductive allure of foods engineered to exploit our deepest instincts.

SWEET SALTY CARAMEL POPCORN

A classic example of a processed food that combines flavours unlikely to be found together in nature is the sweet-and-salty caramel popcorn.

This snack blends the intense sweetness of caramel, which is primarily composed of refined sugars, with the savoury, salty taste of popcorn, enhanced by added salt. In nature, caramel, which is a product of cooked sugar, and salted popcorn, derived from maize with added salt, would never naturally coexist. The combination is engineered to create a highly palatable and addictive flavour profile that plays on the human love for both sweet and salty tastes.

The caramel provides an overwhelming sweetness that satisfies the innate human craving for sugar, while the salt counterbalances it, enhancing the overall flavour and making each bite more gratifying. This combination is so powerful that it can easily lead to overconsumption, as the contrasting flavours keep the taste buds engaged, making it difficult to stop eating. This product exemplifies how the processed food industry can create flavour combinations that are far removed from anything found in the natural world, designed specifically to trigger pleasure responses in the brain and encourage continuous snacking.

NEVER SAY NEVER

New Foundation Farms clearly champions the value of natural foods grown in harmony with nature, recognising them as the most nourishing choices available to us. These foods offer the greatest nutrition per calorie, aligning with our intrinsic needs. However, if we are to embrace a balanced approach to life, we must also acknowledge that processed foods are an inescapable part of our modern existence. Rather than shun them entirely, we can choose to view them as a form of sensory entertainment.

By approaching processed foods as occasional indulgences—enjoyed mindfully and in moderation—we can incorporate them into our diets without compromising our overall health. This perspective allows us to savour the pleasures of food while maintaining a commitment to well-being. Just as there are moments when you might find deep satisfaction in reading Plato, there are other times when a Hollywood movie, with its explosions and spectacle, provides a different kind of enjoyment. The key is to strike a balance, understanding that both Hollywood and the processed food industry are adept at triggering the reward centres of our brain. By recognising this, we can enjoy these experiences without being unduly influenced by their allure, keeping our focus on what truly nourishes us, both physically and mentally.

Why do we taste?