The Evolution of Taste Buds: Why We Crave

By Nathan Robinson


Image Credit: Flickr @ CHRISTOPHER DOMBRES

The effects of evolution have led to many achievements present today. Its effects have been necessary for life to occur and flourish. Unfortunately, the process is nowhere near perfect, as there are many flawed structures throughout earth (the human eye is an example of an inefficient organ). What may have been helpful ten thousand years ago may be detrimental now. The fruits of evolution have turned rotten in the modern era, and one particular product that causes many problems throughout society concerns taste and the brain.


Taste is known to have five distinct qualities: bitter, salty, sour, sweet, and savory (umami). These five tastes can help determine the quality and validity of the food. The method for tasting certain qualities from foods is caused by a process between cells, nerves, and the brain. The tongue contains balls of taste bud cells within lumps called papillae. There are four distinct papillae which look like small or large bumps on the tongue. They each have functions that range from increasing surface area, to sensing temperature. Papillae can help with determining taste, however, the most common type of papillae does not contain taste buds. Nonetheless, filiform papillae’s abundance is necessary, for they have the important role of gripping food. Despites the filiform’s importance, the tongue would not sense taste without the other three papillae. The taste buds in the other three papille distinguish the flavors received on the tongue. A taste bud consists of several different types of cells, which help determine the flavor of the food. A very basic explanation of the process of perception consists of many interactions between the substance and the taste receptors. The presence of certain chemicals in foods will interact with the cells in the taste buds, and if a certain compound is present, then specific cells will send signals to the brain in order to perceive the sensation of taste.


Taste is mostly affected by the tongue, but it is apparent that smell contributes to the perception of taste as well. Receptors in sinus cavities contribute to taste by sensing the presence of food molecules in the air. These food molecules contact receptors by entering through either the nose or the mouth. The receptors can then send this information to the brain. Alone, the sinus receptors cannot provide enough information to develop a great enough flavor. Only a combination between both the receptors in sinus cavities and the taste buds in tongue can produce an adequate taste. The different receptors cannot be independent of each other when attempting to produce a flavor due to their lack of individual information.


Because organisms are incredibly different, their sense of taste is also extremely distinct from one another. The way a food tastes to an organism depends on their environment and how likely the food is to provide them with enough energy. Arguably, humans have one of the worst taste systems for their current environment. Of course this is due to the grindingly slow pace of evolution. Unfortunately, evolution will not “update” taste for thousands or millions of years. Taste may not be “updated” at all, because unhealthy eaters still live up to sexual maturity, and unhealthy eating seems to contribute to mortality after offspring are brought up. Humans have manipulated the natural process which is the cause for much of the strife seen today. The way humans taste now is the same way we tasted in the stone age. The problem with humans is that the environment and lifestyle have changed dramatically in just the past century; the environment is changing faster than we can adapt. The consequences of this can be seen by means of the obesity epidemic: twelve thousand years ago, the agricultural revolution began, which helped produce more food than ever thought possible. There still was not an abundance of food, but it was a step towards progress. Eventually, the industrial revolution led to the mass production of many items which included crops. It was generally beneficial for humans as it diminished starvation rates in first-world countries, but it also contributed to the increased amount of unhealthy and calorie dense products.


Image Credit: Flickr @ stu_spivack

Fast food chains today have modified their foods in a way in order to have a maximum impact on the taste buds which were created for our ancestors. Obesity rates have skyrocketed in the 90s which are most likely due to a manipulation and abundance of foods. Evolution increased cravings for fats, sugars, and meat because it helped humans survive when they consumed more foods containing these substances due to their high caloric output. Now, there is an abundance of food which makes it harmful to eat an excess of foods with these traits. The product of evolution which was once beneficial now reaps a destructive force on most of the population. With more rates of cardiac failure and high blood pressure, it can be inferred that it is due to the increased consumption of unhealthy foods.


What Did You Learn?

Questions:

1. Why can’t humans adapt to eat the most healthy foods?

Technically, humans can “adapt” on their own to fit the needs of the environment. They can do this by changing their diet which may alter their food preferences. Humans can’t adapt fast enough evolutionary-wise though. Evolution takes millions of years to produce beneficial traits, and humans can change entire planets in the span of centuries (in terms of Earth. Terraforming Mars with current technology would take approximately 10,000,000 years [it may be faster with future technology, however]).


2. How does the taste map work?

The taste map has been proven to be extremely misleading. The diagram shows areas of the tongue to be responsible for different sensations of taste. However, the map was misinterpreted and implied that the tastes can only be perceived in those areas. It is clear that taste can be tasted on the pallet of the tongue as well, but more strongly on the sides. The reason for the greater sense of bitterness near the throat, our ancestors could taste bitterness more clearly before swallowing and spit out the substance, for it could be poisonous.


Citations:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6078535/


https://www.dana.org/article/the-senses-smell-and-taste/


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770031/


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163920/


https://www.ncbi.nlm.nih.gov/books/NBK279408/


Image Credit:

  1. https://flic.kr/p/ccyFx7

  2. https://flic.kr/p/brgdMg, License: https://creativecommons.org/licenses/by-sa/2.0/

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