This month's issue of Nature magazine includes a paper by Dr. Ronald DePinho of the Dana-Farber Cancer Institute of Harvard University, describing how he and his team were able to reverse aging in mice.
Now, first, it must be stated that these mice were genetically engineered to have a faulty gene for telomerase, so they aged much faster than normal. Telomerase is an enzyme that protects the end caps on the chromosomes during cell division; the shortening of these end caps (telomeres) is thought to be behind a lot of the less-popular symptoms of aging, including graying of hair, wrinkling of skin, dementia, organ degeneration, and the wearing of knee-high socks with plaid shorts and black leather shoes. The mice, whose telomerase gene didn't work in the first place, were given injections which activated the gene, and the expected result -- that any further aging would slow or stop -- didn't happen. What happened, surprising DePinho's team, was that the aging symptoms actually reversed -- the mice began to repair damaged organs, increase in fertility, and manufacture new brain cells. Some of them even stopped insisting that total strangers look at photographs of their grandbabies.
The conventional wisdom had always been that once the damage was done to the telomeres, reactivating the gene for telomerase was unlikely to rebuild them -- potentially, it could stop further damage, but wouldn't repair the damage already done. Now, it appears that DePinho's team has shown that this is incorrect. And this, of course, immediately raises hopes for the development of an anti-aging therapy in humans.
I find this interesting from two standpoints. First, I'm fascinated with genetics, and anything that further elucidates how genes work is bound to be cool. Second, I'm 50, and am beginning to experience a few of those aging symptoms myself, and I don't like it. I'm not wearing knee socks with shorts yet, I'm glad to say; and I still remember where my reading glasses are most of the time. On the other hand, the laugh lines, stiff joints, and graying hair are a little troublesome. I remember the first time I noticed the gray -- my wife and I were in Iceland, and I decided to forgo shaving for the duration of the trip, and my facial hair grew in gray. Carol's comment was, "You look like Kenny Rogers." The facial hair was gone within ten minutes of our arrival back home. Kenny Rogers, indeed.
In any case, the idea of being able to maintain the vigor and appearance of youth is certainly appealing. However, consider the implications. Suppose they really could drastically slow the aging process, without any untoward results (and it must be said, in the interest of honesty, that one concern about telomerase reactivation is that it might increase the likelihood of cancer). Suppose human life span were drastically lengthened -- you might live to 500 or 600 years, barring an accident. Since growth in size, sexual maturity, emotional/intellectual maturity, and aging are all controlled by different genetic constructs, and only the last-mentioned is being altered, there's no reason to believe that the others would be affected. Therefore, you would reach your adult height at 17 or so, go through puberty at 13 or 14, reach emotional and intellectual maturity in your early 20s -- and then, you'd simply go into stasis. For five hundred years. You'd stand a good chance of meeting your great-great-great-great grandchildren, and when you did, you'd look pretty much like you did when you were raising their great-great-great grandparents. Women would probably still hit menopause in their 50s -- the whole genetic control of sex would, once again, likely be unaffected -- but men would remain fertile indefinitely. (Think of the effect on the population, which is already huge enough as it is.) Then, there are the cultural effects -- people would not just have one career, or two, but twelve or thirteen -- imagine doing the same job not for thirty years, but for four hundred. (The phrase "shoot me now" comes to mind.) Still, would you want to retire at 65 if you still felt like a twenty-year-old? And even if you did, could the current retirement system handle paying out retirement checks to you for 450 years? You think the Social Security System has problems now...
While all of this has the sound of science fiction, Dr. DePinho's team has taken the first steps toward making it possible. And every time I've tried to predict the timing of breakthroughs, I've always been wrong, and the error has usually been an overestimation. (I'm the one who told my AP Biology class "adult-tissue cloning won't be possible for another ten years or more" -- one week before the news of Dolly the Cloned Sheep hit the newspapers.) I'll be watching for further developments, but I'd say that we're not far away from being able to address the whole issue of human life span. I just hope that when it becomes possible, we are careful to consider the implications -- but given our track record of thinking things through, that may be a forlorn hope.