In
Chapter II, Dr. Moalem discusses diabetes. Type 1 diabetes is an autoimmune
disease, where the immune system attacks the cells that produce insulin, thus
no insulin is produced at all and sugar stays in the blood. In Type 2 diabetes
the cells in the body are insulin resistant. The pancreas produces
insulin, but the cells don't respond. So the cells don't get their glucose.
Lastly, gestational diabetes occurs in pregnant women that usually stops after the
pregnancy.
On pages
44-45, Dr. Moalem proposes the theory that diabetes was selected for, in
our European ancestors, during a cold period in the Younger Dryas. The excess
sugar in the bloodstream would act as a natural anti-freeze and prevent
frostbite in appendages. This would prove to be useful when trying to survive
in the cold. Nature would have selected for diabetes in times of extreme cold,
thus many with the disease would be able to survive and reproduce.
In
relation to Big Idea 1, discuss does this theory only account for Type 1 diabetes or
would Type 2 a way of surviving the cold too? And why do so many people have
diabetes now even though we are not experiencing an ice age?
Anna Podber
(apodber3@students.d125.org)
This comment has been removed by the author.
ReplyDeleteBig Idea 1 relates to natural selection: The process of evolution drives the diversity and unity of life. It suggests that only traits will be selected for if the trait gives the individual a higher chance to survive, reproduce, and to pass on that trait into the next generation. The process continues for a long time and, if the selection pressure is strong enough, the trait will become relatively common in the population. This could be how type I diabetes remained in the gene pool. It allowed people to survive the cold better, and thus the genes were passed on.
ReplyDeleteA possible explanation on why this only applied to Type 1 diabetes could be the time in the individual's life that they will start having diabetes. Diabetes type 1 is usually diagnosed in children and teens, while type 2 is mainly in adults. This distinction could be important because the children and teens did not make it to reproductive age yet, so having type 1 diabetes in the cold would be an advantage in surviving the cold and later on to reproduce and pass on its genes. Adults that were diagnosed with type 2 diabetes as an adult, however, had less of an advantage in passing on their genes because they probably had a lower chance of surviving in the cold when they were younger. So, only type 1 helped younger children to make it to adulthood.
http://www.diabetes.org/diabetes-basics/genetics-of-diabetes.html
In page 45 of the book, Moalem described how diabetes helped people survive in the cold, and this was how "survival of the sickest" came to be. This was how people with diabetes continued to survive and reproducing. While it might have been good back then, it is a disadvantage to have it in the present world. However, so many people still have diabetes because its genes are still in the gene pool, and until natural selection exerts enough pressure to "weed out" the people with diabetes, it will continue to linger in the gene pool.
(Hugo Lee; hlee3@students.d125.org)