Sunday, March 10, 2013
Andrew Komarov Blog Big Idea 1
On pages 83-85 of Survival of the Sickest by Dr. Sharon Moalem, Dr. Moalem mentions a genetic correlation between tasting something sweet, salty, or bitter. Dr. Moalem states that the "genes responsible for the growth of bitter taste receptors in our tongues, scientists have traced the evolution of this ability to Africa, sometime between 100,000 and 1,000,000 years ago." (84)
This passage heavily relates to Big Idea #1 because it discusses genetic drift and later natural selection, as Dr. Moalem later mentions when he discusses why some people taste bitterness and others do not. Dr. Moalem states that some people are "highly attuned" to taste while others "can't taste it at all."
How can you explain a genetic drift of a gene that accounts for taste of bitterness and sweetness over a period of over 100,000 years?
Also, discuss how this mutation could be a selective advantage for an animal living in a habitat with poisonous plants.
Andrew Komarov
akomaro4@students.d125.org
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According to Dr. Moalem, the reason that bitterness was able to withstand over 100,000 - 1,000,000 year period is because the ability to taste bitterness was helpful and necessary for survival. Dr. Moalem says, "...we evolved the ability to taste bitterness in order to detect toxins in plants and avoid eating them" (84 Moalem).
ReplyDeleteThis mutation could be a selective advantage for animals living with poisonous plants because when a herbivorous animal comes across a plant and takes a bite out of the plant, the animal is aware of the bitter taste. This reaction tells the animal to spit out the plant because the plant could have toxic compounds within it.
According to "Natural Selection At Work In Genetic Variation To Taste", the ability to taste bitterness developed as a defense mechanism for early humans from eating poisonous plants. According to the article, the reason why tasting bitterness lasted hundreds of thousands of years is, "natural selection has maintained the variation in the gene that allows us to taste or not taste PTC (substance that is bitter or tasteless depending on genetic make up of tester)". This ability today influences what people eat. Also, the article says explaining the cause of genetic drift, "Everybody carries two copies of the PTC taster gene...or one of each". Everyone carrying one or both of the taster genes explains how people over millions of years were able to tell whether a plant tasted toxic based on the bitter properties that the plant had.
http://www.sciencedaily.com/releases/2004/06/040627223325.htm
This relates back to Big Idea #1 because the ability to taste bitterness is a selective advantage because this ability allows a human to determine whether or not a plant is poisonous. The bitterness of plants sends a red flag to our brains that the plant is indeed poisonous and keep us from ingesting the plant. This applies to animals as well.
Genetic drifts are chances of events that change an allele frequency to fluctuate between generations.(Campbell 476). Taste is created through alleles. People obtained these alleles through genetic drift, but kept them in Africa and other parts of the world because taste is a good sensor to protect us. Moalem states that "tasting bitterness gave humans a significant survival advantage"(Moalem 84). Moalem says that humans use bitterness to detect toxins in plants and avoid eating them. This relates to big idea 1 because through the process of natural selection, humans obtained taste as it kept us from eating poisonous plants or other harmful toxins. We can't explain a certain genetic drift for humans to obtain taste for bitterness and sweetness since genetic drift is due to chance, but I can hypothesize that the tastes were obtained through a series of poisonous plants spreading throughout the world or plants starting to produce toxins to protect themselves. Since bitterness detects toxins and sweetness detects safe to eat foods but unhealthy foods, the population of humans with the sense of taste survived and reproduced and therefore humans got the gene for taste of bitterness and sweetness.(http://www.sciencedaily.com/releases/2012/06/120621141401.htm) These help keep us from eating harmful poisons and help guide us to eat healthy and advantageous foods instead of fattening or poisonous foods.As in the article, supertasters choose to eat less sweet foods and less bitter foods. This helps them stay healthy. This is a selective advantage for animals in a habitat with poisonous plants because these animals will choose to stay away from the poison plants due to the bitterness. Also sweetness will cause the animals to stay away from sweet, unhealthy foods since they taste too sweet and help the animal avoid unhealthy, fattening foods.
ReplyDelete(Sam Lee, salee4@students.d125.org)