Friday, June 15, 2012

Dan Eisenberg Discusses Telomere Length and Age

The responses to the interview questions may not represent the views of The Echo Boom Bomb's author. These interviews are provided to inform readers of information from experts and provide these experts with a medium where they can answer questions without any content changes. You can also read other interviews at this link. All media in articles, unless otherwise stated, was added by Tim Smith.

Does a birth from a late father potentially affect the longevity of the offspring? Does it have any impact on telomere length? Dan Eisenberg has studied this and discussed this in a recent finding. I recently interviewed him on his study so that he could explain it. You can find the study here. Dan Eisenberg is a Ph.D. candidate at Northwestern University and has been published with many other authors in peer-reviewed journals (which you can read at the link above this). Along with being a Ph.D. candidate, he's received numerous awards and honors, as well as helped with several humanitarian efforts.

1. What were the findings on your recent study related to older fathers and their children in terms of telomere length?

Telomeres are pieces of DNA found at the ends of our chromosomes that cap and protect the chromosome (like the plastic tips at the end of shoelaces). Each time one of our cells replicates telomeres tend to get a little shorter. So as we get older telomeres get shorter (in tissues in our body which replicate). When telomeres get too short, the cell can no longer replicate and sometimes dies off. Thus, shorter telomeres seem to contribute to deteriorating health with age.

However, previous studies have shown that children of older fathers have longer telomeres (probably because as a man ages, telomeres in his sperm get longer). Our study shows for the first time that this happens across at least two generations: older fathers not only have offspring with longer telomeres, but their sons also have offspring with longer telomeres. That is, having an older grandfather on your dad’s side at the birth of your father predicts that you will have longer telomeres.

This implies that having a father and/or grandfather who reproduced at later ages might cause you to live longer because you were born with longer telomeres. This might be an evolutionary mechanism which allows the offspring to receive a signal of what the environment was like in recent generations. If your father and grandfather were able to live to reproduce at a later age it might be more beneficial for you to invest in having a healthier longer life.

You can read the original study here.

2. How do telomeres relate to health and longevity?

Telomere length is shortened by cell division and replication and shortened telomeres limit the ability of cells to replicate. As such, in general telomeres probably influence cells and parts of our bodies in which cells divide and replicate more. Such cells include our immune system, skin and gut lining. Consistent with this, shorter telomere lengths are associated with increased mortality from infectious diseases and cardiovascular diseases.

However, I also want to note that, as in most science, we need to be careful not to assume correlation is causation. Shorter telomeres in blood are also associated with (and probably caused by) increased stress, infection, poor diet and lack of exercise. Because of this, it can be difficult to definitively discern whether and how much associations between shorter telomeres and poorer later health imply that telomeres are causing this or whether telomeres are more of a marker of past damages. Still there are some good reasons to think that shorter telomeres do actually cause poorer health.

3. I know many people are already asking this question at this point, so I'll go ahead and ask it: outside of aging (for men here), any other ways for people to lengthen their telomeres?

The best bet remains the usual suspects: don't eat too much, eat healthy food and exercise. Meat consumption, particularly processed meat has been associated with shorter telomeres (see here and here also). I'd recommend avoiding any supplement/medication which claims to extend your telomeres.

If you are asking about how men might extend the telomere lengths of their sperm, this is an intriguing question. The only thing I know of that influences sperm telomere length is age. However, my evolutionary theory about father's and grandfather's age influencing telomere length of children as a sort of adaptive signaling mechanism, raises the question of whether other things in men's environments also influence the telomere length of his sperm.

4. Up to this point in your research, what's been your most suprising finding?

To some extent, I was not very surprised by the results. I predicted that the paternal age effect on telomere length would persist across multiple generations in a publication last year in the American Journal of Human Biology (see here). I predicted this because factors like being a first born child or a last born child of a man in the same environment would result in different telomere lengths. But if the effect of paternal age averages across generations than a baby receives not just the signal of what the environment was like for dad, but dad's dad and dad's dad's dad. This could mean that the telomere length a baby inherits conveys a more accurate message about what the recent past environment was like--and what it is likely to be like for that baby growing up.

On the other hand, we only show this association from paternal grandfather's (father's father's age) not maternal grandfathers (mother's father's age at mother's birth). This is peculiar, was unexpected and calls for more research about why there is such a difference in how telomeres are passed on from mothers than from fathers.