You know me; I love to engage in high octane speculation, and when Mr. M.B. shared this article with me, I knew I had to talk about it, because the implications, if the results are replicated, could be quite significant to the current talk about extended human presence in space. NASA, it seems, has been interested in how prolonged presence in space affects the human genome, if at all. So it turned to two twins, Mark and Scott Kelly, to study such effects, particularly on Scott Kelly, who spent a year in space at the international space station.
This, as they say, is where it gets "very interesting." Here's the article:
So what caught my eye? As you might have guessed from the title of today's blog, it's telomeres:
As identical twins, the brothers are genetically very similar. However, researchers found that while he was in orbit, Scott's telomeres — the caps on the ends of chromosomes — grew longer than his twin brother's. Though Scott's telomeres returned to their pre-flight lengths shortly after he returned to Earth, these results were totally unexpected, since telomeres naturally shrink over the course of one's life, and the stresses of spaceflight are supposed to accelerate this. At least that was the idea.
"That is exactly the opposite of what we thought," Susan Bailey, a radiation biologist at Colorado State University, toldNature. (Emphases added)
What's interesting here, and what fuels my high octane speculation of the day, is that there is a school of thought that connects the shrinkage of human telomeres to human aging, i.e., that shrinking telomeres are contributory causes (among others) of human aging. Needless to say, it's a debatable proposition; shrinking telomeres could equally be an effect of aging rather than one of its contributory causes, but in any case, the discussion is there. And before I venture further out on to the twig of high octane speculation where the weight of speculation clearly exceeds the evidence adduced for it, it is also worth mentioning another profound caveat: a study of one man is hardly proof of a general phenomenon. If the phenomenon is repeated in others under the same or similar conditions, then it's not an accident.
But assuming, for the moment, that (1) it is a phenomenon and not an accident, and (2) that the shortening of telomeres is a causative factor in human aging, then the high octane speculative implications are clear: extended stay in space in low or zero gravity might actually contribute to a strengthening and lengthening of the telomeres and hence to human longevity. To be sure, the article points out that telomere lengthening can contribute to the development of pathologies, but under the theory that shortening is a causitive factor to aging and human health issues - as the article also implies with these statements, "John Charles, chief scientist at NASA's Human Research Program, said scientists are interested in telomere length during space travel because their erosion could cause health defects during long-term missions. It is critical to understand these potential health risks before sending astronauts on long voyages, such as one to Mars," (Emphases added) - then their lengthening in space could actually imply that human life extension is enhanced... in space.
Now, in case you think we've crawled out to the end of the twig, we haven't. We're still on the thin branch part, but not quite out on the end of the twig. But now we're going to go there. Under conventional evolutionary theory, beneficial mutations and adaptations are partly in response to environment. Now, while I have all sorts of philosophical problems with standard evolutionary theory, this little telomere story has me wondering: is this an indicator that mankind actually is evolutionarily suited to space? And if so, then why and how did he develop this genome response to the environment of space, if, as the theory holds, he evolved over the ages here on Earth?
See? I told you we were going to go out to the very end of the twig.
See you on the flip side...