On page 84, Dr. Moalem describes a group of people known as supertasters. These people are more sensitive to the tastes of foods, from bitterness to sweetness to spiciness. More specifically, Moalem discusses how these people perceive the bitterness of foods such as grapefruit, coffee, and tea, as well as the spiciness of some peppers. Dr. Moalem also notes in chapter 4 that plants have developed ways to turn away predators to survive and reproduce. These plants are found in specific, localized areas of the world (that is to say, they do not exist in every part of the world).
Knowing these, and using your knowledge of the process of evolution, discuss why you think some people may be more attuned to the bitterness or spiciness of plants than other people. Then, discuss how supertasters may be at a disadvantage over normal humans in regards to nutrition. Use material from class, Campbell, and the book, and connect your ideas back to Big Idea 1, the idea that the process of evolution drives the diversity and unity of life.
Jeeho Lee (jelee4@students.d125.org)
On pages 84 and 85, Dr. Moalem describes “supertasters” as people “highly attuned to taste”. Dr. Moalem explains that these “supertasters” comprise approximately 25% of the human race and are extremely keen to sweetness, bitterness, and spiciness. From an evolutionary standpoint, this phenomenon can be explained via Darwin’s process of Natural Selection, by certain phenotypes that provide a selective advantage for organisms possessing them are passed on from generation to generation. Hypothetically speaking, the prevalence of “supertasting” can be attributed thusly:
ReplyDeleteThroughout the world, plants evolved to produce toxins that make them unappealing to potential predators. Such toxins, which may kill smaller herbivores such as insects, generally have a less severe effect on humans, irritating rather than killing (such toxins include the Capsaicin of chili peppers). However, certain toxins may have had a much more grave affect on human health: the toxins may have interfered with the central nervous system (CNS) or other bodily functions, rendering a human consumer of said toxin unable to adequately survive.
As these plants became more and more prevalent in human diets, the affect of the toxins on humanity became more and more significant. However, there was undoubtedly a mutation in some humans’ DNA; an allele variation of some sort that resulted in such humans possessing the “supertasting” phenotype. These humans were more sensitive to the toxins of the plants, and thus consumed less of the poison. Such limited consumption allowed the “supertasters” to survive and reproduce, while those less keen to the poisons either died earlier (before reproductive age) or were not as fit (could not reproduce as significantly) than the “supertasters”. As generations came and went, the “supertasting” gene was selected for, because it allowed those who possessed it to avoid ingesting toxins, representing a selective advantage for such a trait.
Flash forward to 2013, and it is obvious that being a “supertaster” is not necessarily a good thing. Horticulturalists have all but neutralized any long-lasting effects of plant toxins through excessive research and continuous use; however, the remnants of these ancient poisons can be seen in bitterness and in spice. As Dr. Moalem describes on page 84, “supertasters find more bitterness in grapefruit, coffee, and tea”. This observation is corroborated by a study conducted by the University of Michigan that found that “supertasters” sensitive to 6-n-propylthiouracil (PROP) “disliked naringin…and antioxidants found in cruciferous vegetables”. Cancer prevention research has found that both flavonoids (to which group naringin belongs) and other antioxidants (such as those found in broccoli and Brussels sprouts) contribute greatly to preventing cancer by influencing the methylation of tumor-suppressing genes and other genes instrumental in keeping cancer from metastasizing.
Additionally, “supertasters” are much more sensitive to salt, according to Brown University Ph.D. recipient Linda Bartoshuk. Although salt in excess is dangerous, salt is a necessary part of the human diet, as it maintains electrolyte balances in human bodies and enables communication between the brain and the rest of the CNS (NutritionVista.com). “Supertasters” who are extremely sensitive to salt may run the risk of having a salt deficient diet, in which case they could be at risk for dangerous side effects.
(Justin Millman, jmillma4@students.d125.org)
Supertasters are extremely sensitive to different tastes, such as bitterness or saltiness. Although this ability may seem a nuisance at times to those who are supertasters, there seems to be important evolutionary roots.
ReplyDeleteMany plants evolved to become bitter or spicy over time to deter predators. These flavors signaled to any potential predators that the plant could potentially be dangerous to eat. Over time, the plants that had an unpleasant taste were able to escape from hungry mouths, and these were able to survive and reproduce.
Likewise, humans also began to evolve to meet these pressures. If plants that had bitter or spicy tastes were dangerous, it stands to reason that the humans that were able to detect these stands would be able to survive for longer. An interesting fact I cam across was that 35% of women are supertasters, while only 15% of men are. (http://www.dailymail.co.uk/health/article-173160/Women-better-taste.html) Perhaps this is because throughout history, women tend to be the ones who gathered plants to eat more than men. Therefore, it might have been more useful for women to be supertasters than men in times past.
Thus both the plants that developed bitter or spicy taste and the human super tasters became this way due to the process of evolution, or Big Idea 1. Evolution drives diversity, because it allowed certain traits to be beneficial and thus create a mixture of adaptations in a population, such as 25% supertasters, 50% normal tasters, and 25% nontasters. It also creates unity because difference populations may evolve in response to one another, such as plants and humans.
However, this supertasting ability can come at a cost. Being hyper sensitive to certain tastes can turn off some to certain flavors. For example, many supereaters steer clear of grape fruit, tea, or coffee due to the strong tastes. However, many studies have found healthy compounds in those very foods that supertasters shy away from. For instance, bitter foods have been found to help stimulate digestion, taste receptors, enzyme production, and bile flow. They may additionally help to support the liver. (http://www.besthealthmag.ca/eat-well/healthy-eating/5-health-benefits-of-bitter-foods?slide=3) If supertasters cannot bring themselves to eat these foods, they may suffer negative health consequences as the result of this missing part of their diets.
Carolyn Fan, cfan3@students.d125.org