Can Your Genes Predict When You Will Die?

Can Your Genes Predict When You Will Die?

New research suggests we can defy genetic destiny

• By Joseph Stromberg
• Smithsonian magazine, January 2013

In Greek myth, the amount of time a person spent on earth was determined at birth by the length of a thread spun and cut by the Fates. Modern genetics suggests the Greeks had the right idea—particular DNA threads called telomeres have been linked to life expectancy. But new experiments are unraveling old ideas about fate.

The DNA that makes up your genes is entwined in 46 chromosomes, each of which ends with a telomere, a stretch of DNA that protects the chromosome like the plastic tip on a shoelace. Telo­meres are quite long at birth and shorten a bit every time a cell divides; ultimately, after scores of divisions, very little telomere remains and the cell becomes inactive or dies. And because elderly people generally have shorter telomeres than younger people, scientists believe that telomere length may be a marker for longevity as well as cellular health.

Now researchers are discovering that experiences can affect telomeres—intriguing new evidence for nurture’s impact on nature. In a Duke University study, researchers analyzed DNA samples from 5-year-old children, and again when they were 10. During that interval, some had been subjected to physical abuse or bullying, or had witnessed adults engage in domestic violence. “We found that children who experience multiple forms of violence had the fastest erosion of their telomeres, compared with children who experienced just one type of violence or did not experience violence at all,” says Idan Shalev, the study’s lead author.

Another study, conducted at Brigham and Women’s Hospital in Boston, hints at possible physical effects of chronic stress. Among a sample of 5,243 nurses nationwide, those who suffered from phobias had significantly shorter telomeres than those who didn’t. According to Olivia Okereke, the study’s lead author, “It was like looking at someone who is 60 years old versus someone who was 66 years old.”

“The telomeres are essential for protecting chromosome ends,” says Carol Greider, a molecular biologist at the Johns Hopkins University and a pioneer telomere researcher awarded a share of the 2009 Nobel Prize in Physiology or Medicine. “When the telomere gets to be very, very short, there are consequences,” she says, noting the increased risk of age-related ailments.

While researchers are adding to the list of things that can shorten telomeres (smoking, for instance, and infectious diseases), they’ve also zeroed in on activities that seem to slow down telomere degradation. In a German study, people in their 40s and 50s had telomeres about 40 percent shorter than people in their 20s if they were sedentary, but only 10 percent shorter if they were dedicated runners.

Scientists don’t understand exactly how negative life experiences accelerate telomere erosion—or how positive behaviors stave it off. Additionally, outside of a few age-related diseases in which telomeres have been directly implicated, they’re unable to say whether shorter telomeres cause aging or merely accompany it. But it’s clear the fates aren’t entirely in charge. According to the new science of telomeres, we can, to some extent, influence how much time we have.

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• Read straight from Smithsonian Magazine

View related video Decoding Immortality

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ADDITIONAL INFORMATION

Molecular biologist Elizabeth Blackburn–one of Time magazine’s 100 “Most Influential People in the World” in 2007–made headlines in 2004 when she was dismissed from the President’s Council on Bioethics after objecting to the council’s call for a moratorium on stem cell research and protesting the suppression of relevant scientific evidence in its final report. But it is Blackburn’s groundbreaking work on telomeric DNA, which launched the field of telomere research, that will have the more profound and long-lasting effect on science and society.
In June, we hosted Catherine Brady who told the story of Elizabeth Blackburn’s life and work and the emergence of a new field of scientific research on the specialized ends of chromosomes and the telomerase enzyme that extends them. On Monday, August 18th we welcome Elizabeth Blackburn herself to our Google San Francisco office.
This event took place on August 18, 2008, as a part of the Women@Google series.

Σχετική διάλεξη σε αρχείο pdf για προσωπική χρήση

• Αναπαραγωγική Γήρανση

Απο την Ελληνική Μυθολογία, Ησιόδου Θεογονία
Ι.Ρίσπεν, εκδόσεις Βίβλος, Αθήνα 1953

Η Νύξ εγέννησε τάς αμειλίκτους Μοίρας Κλωθώ, Λάχεσιν και Άτροπον,
αι οποίαι μοιράζουν το καλόν και το κακόν είς κάθε θνητόν την
στιγμήν που γεννάται, τιμωρούν τα εγκλήματα των ανθρώπων και των
θεών και δεν παύουν την οργήν των παρά αφού εκδικηθούν κατά
τρόπον τρομερόν.
Σε μια άλλη μεταγενέστερη εκδοχή
Η Θέμις, γενομένη σύζυγος του Διός, εγέννησε την Κλωθώ, την Λάχεσιν
και την Άτροπον αι οιποίαι μοιράζουν εις τους ανθρώπους τα καλά και
τα κακά.
Αι Μοίραι παίζουν σημαντικώτατον ρόλον είς την ελληνικήν Μυθολογίαν.
Αντιπροσωπεύουν μίαν δύναμιν, ή οποία εφορεύει επί της ζωής
τών ανθρώπων από της γεννήσεως μέχρι του τάφου.
Τας παρέστησαν υπό την μορφήν γυναικών, αι οποίαι κλώθουν,
την δε ζωήν των ανθρώπων ώς νήμα, το οποίον κόπτεται είς
πάσαν πράξιν της ζωής.
Τόσον η ενυπάρχουσα είς την ανθρωπίνην ζωήν δύναμις
είναι μικρά και εύθραυστος.
Το νήμα παριστάνει ή ότι έχει ήδη γίνει, ή ότι γίνεται τώρα.
Μία απο τας Μοίρας αντιπροσωπεύει το παρελθόν, είναι
η Άτροπος και ονομάζεται έτσι, διότι όσα έγιναν
δεν υπάρχει τρόπος να αλλάξουν.
Το μέλλον το αντιπροσωπεύει η Λάχεσις, διότι το τέλος,
σύμφωνα με την φύσιν, εκδηλώνεται είς όλα τα πράγματα.
Το παρόν, τέλος, το αντιπροσωπεύει η Κλωθώ, εκείνη που
κλώθει δια κάθε πράγμα ότι αναφέρεται είς αυτό.

Η Θεογονία στα Αρχαία Ελληνικά σε αρχείο pdf

• Ησίοδος Θεογονία

Featured image collected from :

http://www.tovima.gr/science/medicine-biology/article/?aid=484759
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Joseph Stromberg (2013).
Can Your Genes Predict When You Will Die?
Smithsonian.com

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