On page 158-163 Dr. Moalem talks about epigenetics and fetal development. Moalems says that a mother's nutrition during pregnancy will lead to her child's genes being expressed differently. Poor nutrition during pregnancy could lead to overweight children. This relates to Big Idea 3 (Living systems store, retrieve, transmit, and respond to information essential to life processes). David Barker was the first to suggest a link between poor fetal nutrition and obesity. He proposed the Barker Hypothesis, or the thrifty phenotype hypothesis. What is this hypothesis? What does it mean to have a "thrifty phenotype"? According to the hypothesis, 10,000 years ago during a famine, having this thrifty phenotype helped people to survive and reproduce. Why did this help people then, but cause obesity now? Based on this research, how should a pregnant mother today eat, in order to prevent obesity in her child?
(Julianna Holzer jholzer4@students.d125.org)
The Barker Hypothesis states that decreased growth of fetus is directly related to chronic conditions later in life, usually Type 2 Diabetes and metabolic syndromes, according to Oxford Journals.To have a thrifty phenotype means that the phenotype of the child is modified to be prepared for natural selection in a hostile, resource-scarce environment (Biology Online). Thrifty phenotype also causes the person to have poor insulin production, thus causing decreased energy expenditure and ultimately obesity (Oxford Journals).
ReplyDelete10,000 years ago, perhaps during a famine, there would be scarce resources. Thus, humans and their offsprings needed to compete with themselves and others to increase survive and reproduce. Having a thrifty phenotype would be beneficial to surviving in such hostile conditions in that low insulin production and decreased energy expenditure would allow the person to have lower metabolism rate and decrease the frequency of necessary food intake. Decreased food intake and energy conservation would allow the person to be favorably selected in a resource-scarce environment and thus increase his chances of survival and reproduction in natural selection (Campbell 475). This, however, is unhelpful in today's environment because we have an abundancy of food, so energy conservation isn't really necessary. Having thrifty phenotype would cause the person to conserve unnecessary glucose/energy, slow metabolic rate, and ultimately cause obesity: all because of the difference in amount of food available 10,000 years ago and now. This also relates to Big Idea 3 (Living systems store, retrieve, transmit, and response to information essential to life processes) in that scarce nutrients exposure causes the baby's body (living system) to modify its phenotype so that it is better prepared to increasing its survival chances in a hostile environment.
In order to prevent obesity/thrifty phenotype in her child, a pregnant mother should eat a variety of foods to expose the child to an abundant amount of nutrients. The pregnant mother should eat lots of fiber, grains, fruits, vitamins, and iron. Proteins should also be consumed regularly. This will allow the child's metabolism to increase, increase insulin production, and thus increase energy expenditure. This will, in turn, result in prevention of obesity (WebMD).
Sources: http://bmb.oxfordjournals.org/content/60/1/5.full
http://www.webmd.com/baby/guide/eating-right-when-pregnant
http://www.biology-online.org/dictionary/Thrifty_phenotype
Paul Sone jsone4@students.d125.org