Good morning everyone,
As we enter the last quarter of out term, we soon will be considering the remaining chapters in our text, on topics including digestion, immunity, metabolism, and reproduction. These are relatively 'integrated' phenomena - complex and intertwined with other of our physiological systems and processes.
In the science news this week is a report that is similarly integrated, on simultaneously both a larger scale (the entire body) and a smaller one (examination of just one person, relative to one other).
Nearly all quality research in physiology (like that of other fields) relies on large sample sizes - studies of hundreds, thousands, or even millions of individuals. The larger the sample, often the greater the statistical power of the comparisons, the ability to detect tiny effects. Does this drug lower blood pressure? How does a vegan diet influence sleep habits? What are the genetic components of immunity? Studies like these would never evaluate one or two subjects, because the ability to generalize the results would be very low. And, studies employing few subjects would be very unlikely to be funded or pursued, for exactly that reason.
But, NASA's study of astronaut Scott Kelly (and comparison to his Earth-bound twin Mark) is quite unique, in many ways: how many of us will ever spend (nearly) a year in space? So, far, perhaps just a handful of people. How many of these individuals have an identical twin? Just one.
Scott and Mark were subjected to a battery of tests before, during, and after Scott's 340 day long space aboard the International Space Station. How does a life in space influence the body? Well, in many ways, as it turns out. Why do we care? Because, as a society, we continue to push the boundaries of space travel, and long journeys in space (to Mars, or other places) are surely on the horizon. What will happen during those trips? Scott and Mark Kelly offer a useful, and unique window into this problem. Because they are genetically identical, in theory, any differences between them should be due to their environments. If they were carefully evaluated before, and then after, Scott's year in space, it should allow us to see what space travel does to the body, by comparing Scott and Mark.
If Scott Kelly is a useful model, life in space will be very challenging, physiologically. Among the largest changes noted upon his return to Earth were cognitive deficits, colonization of his body by different kinds and numbers of bacteria, indicators of high stress levels (no surprise), many genetic mutations, and, surprisingly, longer telomeres on his chromosomes. This last finding was unexpected - telomere length is a sign of cell age, and long telomeres are normally interpreted as a sign of youth. Does space travel reverse aging? Probably not! It's more likely that the rigors of space life (especially the radiation exposure) triggered lots of repair and replacement of damaged cells, and newly created cells may have higher levels of telomere maintenance.
In many ways, Mr. Kelly has offered himself as a 'guinea pig' for these studies - even now, back on Earth for years, many of his symptoms and genetic mutations remain. Was it worth it? His answer is an unequivocal 'yes'. Like other astronauts before and after him, his experiences were literally other-worldly. Our technological advances toward space may be outpacing our physiological ones, however. If Mr. Kelly's response is typical of what will happen to the human body in space, we have much to learn, and much work to do, before long-term stays in space will become feasible.
Not to say that all of the news is negative: he took some amazing photos while he was there:
Have a great weekend -