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Childhood Stress Leaves Genetic Scars
sciencehabit writes "Traumatic experiences in early life can leave emotional scars. But a new study suggests that violence in childhood may leave a genetic mark as well. Researchers have found that children who are physically abused and bullied tend to have shorter telomeres — structures at the tips of chromosomes whose shrinkage has been linked to aging and disease."
A study (http://www.pnas.org/content/109/17/6490.full) was published in PNAS today showing how low-ranking monkeys have worse immune systems than high-ranking monkeys. (In monkey societies, 'high-ranking' is a euphemism for bully.) We've known for a long time that subordinate monkeys have worse health and live shorter lives in general than dominant monkeys, but this is one of the first studies that describe how this actually happens, genetically and physiologically.
Actually, if you RTFA you would know that the measurement only applied to two or more kinds of violence exposure. Thus, the occasional spanking without other forms of violence would not qualify as harmful under this study.
It used to be taught that environmental factors during an organism's lifetime (malnutrition, etc.) did not have an effect on the genetic heritage of offspring (you get a "clean slate" of DNA, so to speak). [...] But here we are with a study that says environmental factors can leave a genetic mark.
The study was about somatic cells, eg "body cells" that make up the specialized tissues of your body. Your offspring are formed from germ cells, found in your gonads, and consequently your offspring can only inherit DNA from your germ cells, but never your somatic cells (except in the case of cloning or other artificial techniques).
Telomeres are the "endcaps" of chromosomal DNA. Every time a chromosome is copied, a small portion at the ends of the chromosome get "left off" of the copy, which limits the number of time a cell can divide before the telomeres are consumed and functional DNA segments begin to be deleted. This (usually) prevents cells from reproducing in an uncontrolled fashion, and it's one of your body's main defenses against cancer. That's how it works in somatic cells.
Germ cells, on the other hand, can express a ribozyme called "telomerase," which can bind to the ends of a chromosome and extend the telomeres. This is why animals can reproduce indefinitely even though 99% of their cells are "mortal." (As others have pointed out, when a somatic cell begins to express telomerase it's usually cancer.)
The upshot of all of this is that shortened telomeres in your somatic cells will have no direct effect on your offspring. This particular study in no way supports the idea that environmental factors are responsible for genetic changes in offspring. Your post is therefore ill-informed even if your thesis is correct ("almost everything they teach in American public school is either wrong or simplified to the point of uselessness?").
To rectify your error, your homework assignment for tonight is to study the enzymes called "telomerase" and "reverse transcriptase," followed by learning the "central dogma of biology."
Dismissed.