Here’s how sweet, sour, salty, bitter, and umami guided early humans and still impact us today
Let me start with a question.
When you think of your sense of taste, what do you think is its purpose?
I mean is there any reason we have five basic tastes called sweet, sour, salty, bitter, and umami?
You might assume that taste simply allows us to enjoy our food, but the truth is much more interesting. Taste has far greater implications than a nice, flavorful dinner.
In fact, each of our five basic tastes are thought to have played a role in ensuring the survival of early humans.
I know this idea of taste aiding in survival might sound absurd, but think about the times in your life where your taste preferences have changed with what you’ve eaten.
After a bad case of food poisoning, you instinctively avoid the food you suspect got you sick. Just the thought of eating that food again is enough to make you nauseous.
And during the early months of pregnancy, women become extremely sensitive to bitter tastes. Although not all bitter tastants are toxic, many of them are, so our sense of taste is attempting to protect the fetus during its most vulnerable time.
It’s in these subtle ways that your taste buds may be running your life more than you realize.
Let me illustrate just how sweet, sour, salty, bitter, and umami tastes have impacted our ancestors and still guide our lives today.
Sweet
For those of us with a sweet tooth, it can seem near impossible to stay away from those candies and confections.
But, would it make you feel better if this love for anything sweet is linked to human survival?
Imagine early humans who foraged and hunted for their food. They burned huge amounts of calories and energy just searching for food, unsure if, or when, they would find any.
Meals weren’t as convenient as simply walking to your kitchen.
To our early ancestors, sweet-tasting foods like fresh fruit would symbolize sugars, energy, and life for another day. It was just what they needed to refuel and revive their body. It was basically like winning the food lottery.
Compare this to today, where we are constantly surrounded by these highly-processed, sugar-filled foods. Do you see a problem?
Our desire for sweets is still linked to these foods being seen as rewards that are prized for their calories and carbohydrates. Even newborns are attracted to sweet tastes just as adults are.
While this connection between sweet taste and energy would have been useful at a time when dietary mistakes were lethal to early humans, it seems to have backfired on us in the present day.
Food is all too convenient and our lifestyles more sedentary. Eating too much sugar now leads to numerous diet-related diseases like obesity, type II diabetes, and tooth decay.
So, while the innate desire for sweets was truly advantageous for early humans, it’s no longer helpful in a world that’s brimming with sugar-laden treats, excessive calories, and chronic disease.
Sour
Foods are perceived as sour any time an acid is present. It’s really the protons (or hydrogen ions) in the acid that trigger our sour taste buds and the overall intensity is related to the amount of protons present.
Now, I’m not talking about strong acids like sulfuric acid that could burn your skin right off, but weak acids that are naturally present in foods.
For example, milk products contain lactic acid, apples contain malic acid, and grapes contain tartaric acid. The amount of acids in these foods is smalland gives us a little hint of sourness.
The opposite is true for spoiled food where bacteria have produced largeamounts of acid.
And this is bad news, with so much bacterial growth, spoiled food is likely to make us sick. You can count on some quality time with your toilet if you make a habit of eating spoiled.
Luckily, the high concentration of acid in these rotten foods set off our sour taste buds. The extreme sourness sensed in the mouth signals the body to immediately expel the food before swallowing.
In this way, our sour taste buds act as security guards that decide which food is safe to pass into our body and which food would be better off spit out. A little sourness is tolerated, but a high amount triggers our body to go into self-defense mode.
Salty
Around the globe and across all cultures, humans use salt in their cooking — which is a major clue that there’s some biological reason behind ingesting salt.
Now, the salt you’re probably most familiar with is table salt or more scientifically called sodium chloride (NaCl).
In table salt, it’s really the sodium ion, Na+, that triggers a salty taste in our mouth. In fact, any positively charged ion — often called a cation — can trigger our salty taste receptors.
Other cations like calcium (Ca+) and potassium (K+) are also common in food and taste salty, but cause off-flavors like bitter, metallic, and astringent. Sodium chloride is really the only salt with a clean taste, which explains why it’s so ubiquitous in our food supply.
Now, why do we need salt?
It’s really the sodium cation that’s critical to maintaining the right balance in the fluid that surrounds our cells.
Unfortunately, the human body is terrible at storing sodium since it gets expelled through sweat and urine. This means we have to consistently have some type of low level salt intake to manage our extracellular fluids correctly.
But, it’s an entirely different story for high levels of salt.
You may have experienced this if you’ve ever over-salted a dish. At too high of concentrations we find salt repulsive.
Why would that be?
Well, eating salt in large amounts throws off the osmotic balance of the fluid that surrounds our cells and over a lifetime can lead to hypertension and kidney disease.
So, our innate aversion to exorbitant levels of salt is actually trying to protect us and keep the body running in peak condition.
This means the real value of saltiness as a basic taste, is its ability to steer us towards eating the right amount of salt. And when it comes to salt in the diet, there seems to be a sweet spot (no pun intended here).
I suppose you could call it the Goldilocks approach — not too big, not too small, just right.
Bitter
As an adult, I’ve grown to enjoy many bitter foods like coffee, tea, and vegetables, which I had previously despised as a child.
Maybe you’ve noticed this same pattern in your own life?
And you wouldn’t be alone, newborns are innately averse to bitter-tasting foods. This explains why babies tend to spit out vegetables the first couple of times they try them — their body tells them to reject the bitter food.
This repulsion to bitter compounds is thought to have evolutionary significance since many bitter molecules are toxic to humans.
A majority of bitter-tasting compounds originate from plants and are often part of the plant’s defense mechanism, because after all, a plant doesn’t want to be eaten. These bitter toxins are made by plants to fend off animals and keep the plant alive.
Beyond plant toxins, many bacteria produce bitter-tasting toxins as they spoil food. So, if a food has gone rotten, the bitterness lets us know that the food is unsafe to eat.
Essentially, our bitter taste receptors can act as an alarm system that alerts the brain when high levels of toxins may be in the mouth.
And the receptors can actually trigger a bodily response to minimize poisoning by promoting a nauseous feeling and changing how the stomach contracts to create a more chaotic pattern. These reactions help keep the toxins in the upper GI tract and promote vomiting.
It’s these feelings of sickness and gastrointestinal malaise that act to punish us for making poor food choices and protect us from ever making the same mistake again. This is true whether you’re a human who lives today or 1,000 years ago.
Umami
When it comes to umami — the most recently discovered basic taste — two different theories of evolutionary significance are in play.
Both theories focus on L-glutamic acid, which is an amino acid that triggers the umami taste response.
L-glutamic acid isn’t the only molecule that elicits the umami taste, in fact a couple of other compounds do including most popularly MSG (monosodium glutamate) along with IMP (inosine monophosphate), and GMP (guanosine monophosphate).
Much of the focus is on L-glutamic acid, however, since amino acids are the building blocks of proteins, which is a key nutrient in our diet.
The first theory suggests that if amino acids like L-glutamic acid trigger the umami response, it can be used as a rough estimation of the protein content within foods. This would help early humans pinpoint what plant and animal are good sources of protein.
The second theory points out that large amounts of L-glutamic acid are also present in food after it’s been fermented. This could be important considering that fermentation was one of the earliest food preservation techniques used by humans.
Linking fermented foods to the umami taste receptors would entice humans to eat more of these foods, which have a very unique nutritional profile. Not only are fermented foods rich in macronutrients like protein, carbohydrates, lipids, and water, but also vitamins and minerals.
Not to mention, they contain beneficial microorganisms — called probiotics — that are helpful in maintaining a healthy gut and preventing disease.
Ultimately, the two theories do diverge on which type of food our umami taste buds are attracting us to, but both theories suggest that umami tastants helped guide early humans to more nutritious forms of food.
It may be protein-rich foods, or perhaps fermented foods, but either way the conservation of umami taste buds in humans over time alludes to some form of significance.
The real and perhaps unexpected value of our five basic tastes is to guide our dietary decisions and keep us safe.
I suppose they also allow us to enjoy a delicious meal, but that seems secondary to the whole thing about helping us stay alive.
Over time, the taste receptors to sweet, sour, salty, bitter, and umami compounds have formed an intricate system that allows humans to evaluate the nutrients in food and reject any substances that may be harmful.
And even now, when many of us have a kitchen full of safe, nutritious food, our eating habits are still steered by the same system used by our ancestors hundreds, if not thousands, of years ago.
