The Tastes
On page 84,
according to Dr. Sharon Moalem, the research, done by University College
London, Duke University Medical Center, and the German Institute of Human
Nutrition in 2005, formed a conclusion in the
following: the reason why human “evolved the ability to taste bitterness” is to
avoid ingesting plants that are toxic, which is related to the Big Idea 1 (The
process of evolution drives the diversity and unity of life).
Explain how scientists proved that “the ability to
states bitterness” was not naturally given to human but evolved and provide one
evidence, at least, to support their conclusion. Also, define antifeedants and provide one example of
“beneficial” compounds that taste bitter.
Lastly, define umami,
the fifth taste, and research why “other parts of the world” developed the
fifth taste. Also, research one other example of foods that taste umami. Consider Dr. Moalem’s claim on
page 84: “Most tates are pleasing, and the evolutionary reason for them is
simple-they attract us to foods that contain nutrients, as well as the salt and
sugar, that we need.”
(Posted
by Fabiola Yun, jooyun4@students.d125.org)
This comment has been removed by the author.
ReplyDeleteThe ability to taste bitterness relates to Big Idea 3: Living systems store, retrieve, transmit, and respond to information essential to life processes. Humans have the ability to taste bitterness because, in a time of hunters and gatherers and farmers, it would help humans keep away from plants that are toxic and could potentially kill them. This trait, then, would be selected for in evolution by natural selection, since avoiding dangerous plants increases the chances of humans surviving and reproducing.
ReplyDeleteHow does taste work? On a human’s tongue, each taste bud is composed of between 50 to 100 taste cells. Each taste cell has transmembrane proteins called receptors. These receptor proteins allow ions (like Na+) that lead to a salty taste to enter the cell through facilitated diffusion. Receptors also bind to molecules that lead to the tastes of sweet, bitter, and umami. When a receptor binds to a molecule, it triggers a nearby sensory neuron that leads back to the brain—this is what actually produces the sensation of tasting something sweet or bitter. (http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html#sour)
Scientists proved that being able to taste bitterness is an evolved trait by constructing genetic history of a gene that helps bitter taste receptors grow. By tracing the history of this gene, scientists found that the ability originated in Africa, “between 100,000 and 1,000,000 years ago” (pg. 84). One way to tell that this is an evolved ability is that “not all humans have the ability to taste bitterness” (pg. 84), meaning that some people (though not many) do not have genes that lead to bitter taste receptors on the tongue. Additionally, different people have different levels of sensitivity to bitterness (pg. 84), which means there is genetic variation in the human population, something essential for the evolutionary process.
The fifth taste, umami, is a “savory flavor” that is most common in “aged and fermented foods” (pg. 84). This sensation is caused when a taste receptor on a taste cell binds to salts from glutamic acid. Umami is gaining popularity in the Western world because many common foods have the taste of umami. One reason that umami was discovered and developed in other parts of the world is that the term was created by a Japanese scientist and he used a food common to Japanese cooking: dashi stock made from kelp (http://www.umamiinfo.com/2011/02/the-discovery-of-umami.php). Later, it was discovered that many common Western foods also contain umami. Examples of food that contain umami include different vegetables such as tomatoes, shiitake mushrooms, and carrots (http://www.umamiinfo.com/umami-rich-food/). This supports Dr. Moalem’s claim that “tastes are pleasing” because they “attract us to foods that contain nutrients…that we need” (pg. 84). The taste of umami is pleasing and it attracts us to the vegetables mentioned above, which contain vitamins and minerals our bodies need for biological processes. Umami is also present in seafood and some other meats—these contain protein necessary for muscle growth and other nutrients.
(Sanika Bhargaw, sbharga4@students.d125.org)