In page 35-36 of the book, Dr. Moalem discusses the differences in the body's defense system to the cold. Although everyones body reacts the same way in that the body shivers, then the body gets a tingling sensation, Moalem describes how there are other differences to how people from different regions react to cold. In people that live or have had ancestors from particularly cold climates, they have a system called "hunter's response" in that they have an ongoing cycle of constriction and release of blood to provide warmth to all parts of the body. However, Moalem suggests that African Americans(ancestors who lived in very warm climates) do not possess this ability. This is in accordance to Big Idea 1, and how evolution drives the diversity of life and Big Idea 3 and how the body responds to signals outside the body, such as cold.
What system or body part allows the body to understand the temperature outside and react to it? Also, explain at least two other examples of where temperature or climate has affected the body and its reactions from people from another part of the world. Be specific and describe thoroughly. Does the body have different reactions to warm climates as well?
Also according to Big Idea 1 and Big Idea 2, on page 36-37, Moalem also describes another cold response that the body will do only if you are in cold temperatures. This cold response is a heat-generating tissue called brown fat, but Moalem suggests that if you are not in a North Pole-type climate, than your body has little to no brown fat.
If evolution happens over many, many generations, then how is it possible that in just a few weeks of living in a very cold climate, a person can have brown fat cells and utilize this ability? How has this brown cell ability come into the body? Has it always been there for human beings or is it an evolved trait as well?
-Rudy Viswanathan (aviswan4@students.d125.org)
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