Telomere Length and Life Expectancy in Warblers

Researchers are making better progress of late in finding ways to use changes in telomere length that occur with aging as a marker for biological age and life expectancy - though it remains an open question as to whether telomere shortening is a cause of aging versus a secondary consequence of causes of aging. You might look at work in mice published earlier this month, for example. Or moving to birds, a few years back researchers noted that pace of telomere shortening over time correlated with lifespan differences between species. Here researchers consider telomere length in a species of warbler:

[Researchers] studied the length of chromosome caps - known as telomeres - in a 320-strong wild population of Seychelles Warblers on a small isolated island. ... Over time these telomeres get broken down and become shorter. When they reach a critical short length they cause the cells they are in to stop functioning. This mechanism has evolved to prevent cells replicating out of control - becoming cancerous. However the flip side is that as these zombie cells build up in our organs it leads to their degeneration - aging - and consequently to health issues and eventually death. Telomeres help safeguard us from cancer but result in our aging.

We wanted to understand what happens over an entire lifetime, so the Seychelles Warbler is an ideal research subject. They are naturally confined to an isolated tropical island, without any predators, so we can follow individuals throughout their lives, right through to old age. We investigated whether, at any given age, their telomere lengths could predict imminent death. We found that short and rapidly shortening telomeres were a good indication that the bird would die within a year.

We also found that individuals with longer telomeres had longer life spans overall. It used to be thought that telomere shortening occurred at a constant rate in individuals, and that telomere length could act as an internal clock to measure the chronological age of organisms in the wild. However while telomeres do shorten with chronological age, the rate at which this happens differs between individuals of the same age. This is because individuals experience different amounts of biological stress due to the challenges and exertions they face in life. Telomere length can be used as a measure of the amount of damage an individual has accumulated over its life. We saw that telomere length is a better indicator of life expectancy than chronological age - so by measuring telomere length we have a way of estimating the biological age of an individual - how much of its life it has used up.



Isn't this a bit self evident? I know there's no garauntees in Science but this study took over 20 years to vaguely confirm what? DNA integrity is important to the longevity of an organism? Isn't this typical of curiosity driven science? I mean telomerase was discovered in 1984. Wouldn't the next natural thing to do be test if effects on organisms? Apparently it isn't. The next natural thing to do is look at the telomere length of birds for 20 years.

Posted by: Glen at November 22nd, 2012 3:45 AM


While I can understand your frustration, I think you vastly overestimate what we know and vastly underestimate both the difficulty and value of performing the tests you mention. The people who did this study weren't idiots and didn't want to waste their time; if it were as easy or natural as you mention, they would have done something different.

Hindsight is always 20/20, but that doesn't mean the initial search should have been easy.

Posted by: Dennis Towne at November 22nd, 2012 1:44 PM

I don't think hindsight is 20/20 in this case. I think this is just another example of curiosity driven science as well as add to redundancy. Similar experiments were conducted in a human population and they likewise don't illustrate a lot. Even if it did this kind of science is more about observations rather than interventions, i.e. it does not have any premise for a proposed intervention.

Posted by: Glen at November 23rd, 2012 1:36 AM

I think a lot articles we read are already outdated. I wonder sometimes if it is because anyone who is onto something must do a great deal of tests and then obtain patents before disclosing anything. And even then they are somewhat secretive about it and rightfully so in the world of world patent infringement. Still, I think science could move more rapidly especially when it comes to such important things as life extension and quality.

Posted by: Merrill at November 27th, 2012 5:20 PM

This study does seem redundant. However, part of the empirical method is to confirm findings thru replication by other groups of scientists. Still, I would like to see more experiments where some risk is taken, especially when animal models are used. What would happen if you took a group of old chimps and juiced them full of telomerase? Perhaps you could start with nematodes or protozoa. If my skin was becoming thin and had reduced elasticity, and I applied a topical cream with telomerase, what would happen?

Posted by: Steve at November 28th, 2012 8:46 AM

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