On pages 168-170, Dr.
Moalem discusses an experiment conducted in 2004 at Duke that tested the
effects of interaction between mothers and their offspring on epigenetic
markers. We know that many epigenetic markers are created before the offspring
are born, but little is known on the effect on epigenetics directly after
birth. The explanation for this relates to Big Idea 3 (living systems store, retrieve,
transmit, and respond to information essential to life processes).
What effect do
different levels of attention from their mothers have on mice the first
few hours after birth? What is the biological reason for this (think
epigenetics and gene expression)? Does this
result lean towards the side of nature or the side of nurture as being more
important? What connection can you draw to human infants from these results?
Using outside information and your own knowledge, describe the differences in cognitive development
and epigenetic markers in an r-selected species and a K-selected species.
-Mikhail Iouchkov (mikhailiouchkov@gmail.com)
After giving birth, mothers of mice gave different levels of attention to their offspring. The mothers that cared for their babies more and gently licked them grew to be more confident, relaxed, and better at handling stress. Babies that were ignored or payed less attention to were much worse off, being very nervous later in life.
ReplyDeleteEven though these results seem to have occurred because of the nurturing they were exposed to, there is a definite genetic reason for this. Methyl markers in epigenetic are when a methyl group is attached to either DNA or proteins to turn certain genes on or off; the addition of methyl groups turns genes off, the removal of methyl groups turns genes on. When the baby rats were groomed carefully, they had a decrease in methyl markers that blocked the genes involved in brain development with regards to stress response. The babies who were not nurtured had more methyl markers on the parts of the brain vital to developing stress relief, so they were not able to cope as well with their nerves.
To make sure the experiment was not due solely to genetics, they switched the offspring of the caring rats and the harsh rats, and achieved the same results. This shows that it was a case of both nature and nurture that develops what genes are expressed and how a rat behaves. Dr Moalem even goes against the long lasting debate of nature versus nurture by saying, "This wasn't nature versus nurture; this was nature and nurture" (169).
These experiments have many applications to humans. epigenetics works similarly between all species because methyl groups exist in both animals like rats and humans. Also, the study of epigenetics can be used in relation to humans to help cure diseases. "Many medical treatments such as those being developed for cancer and schizophrenia try to coax the epigenome into changing its mind" (http://www.livescience.com/7736-epigenetics-revolutionary-humans-work.html). Specifically regarding the nurturing of human babies compared to the nurturing of baby rats, these experiments put a new light on the importance of taking care of children when they are extremely young because that is when a lot of the epigenome is being put into place and when the methyl groups are mostly getting settled. Epigenetics as a whole relates to Big Idea 3, living systems store, retrieve, transmit, and respond to information essential to life processes, because methyl groups affect how genes are expressed which affects everything about a living system with regards to information. Methyl groups provide the information on what to express, and living systems respond accordingly.
K-selected species normally are large, have few offspring, have late maturity, have more parental care, have a long life expectancy, can usually reproduce more than once, and have type I or II survivorship curves where most individuals live to near the maximum life span. r-selected species are basically the opposite. They normally are small, have many offspring, have early maturity, have short life expectancy, usually only reproduce once, and have type III survivorship curves in which most individuals die in a short time. Overall, although epigenetic would affect both types of species over their lifetimes, the markers would affect K-selected more because they have a longer period of parental care in which their methyl markers are most easily provoked and changed. So while epigenetic markers change throughout all organism's lifetimes, K-selected organisms would be more greatly affected.