Aubrey de Grey is a well-known futurist, with a twist. A few months ago, Technology Review had a profile of de Grey, that starts like this:
Aubrey David Nicholas Jasper de Grey is convinced that he has formulated the theoretical means by which human beings might live thousands of years -- indefinitely, in fact.
Perhaps theoretical is too small a word. De Grey has mapped out his proposed course in such detail that he believes it may be possible for his objective to be achieved within as short a period as 25 years, in time for many readers of Technology Review to avail themselves of its formulations -- and, not incidentally, in time for his 41-year-old self as well. Like Bacon, de Grey has never stationed himself at a laboratory bench to attempt a single hands-on experiment, at least not in human biology. He is without qualifications for that, and makes no pretensions to being anything other than what he is, a computer scientist who has taught himself natural science. Aubrey de Grey is a man of ideas, and he has set himself toward the goal of transforming the basis of what it means to be human.
De Grey has set himself up as just the gadfly to prod biologists to make it happen. Consider this essay, where he describes researchers on aging as "catatonic" for standing mute before his agenda.
And an agenda is what SENS is. The central idea is that the causes of aging are finite. De Grey lists seven basic causes, and argues that there likely aren't any more to be found, since no new ones have emerged in over twenty years. The seven range from an accumulation of mitochondrial mutations to programmed cell death and the breakdown of extracellular support structures. SENS seeks to find ways to nullify these seven causes of aging.
Not bad for a start. De Grey and others have identified in principle some ways that each of the seven causes could be stopped. It's when you read into these details that you begin to comprehend the breathtaking ambition behind the agenda. How to solve the problem of mtDNA mutations? No problem --- just replace the body's stem cells with others that have the 13 mtDNA genes present in the nucleus. And find ways to make them active in the right amounts. And work out a way to get them across the mitochondrial membrane. The thing is, they have ideas about how all these things might be done. The only barrier is, of course, is finding out whether all these steps will work.
The main focus is cellular aging, but to the extent that stem cells might be able to replace tissues with younger, more functional versions, the focus is probably what is needed. But there are plenty of stumbling blocks. Cells are Rube Goldberg devices, with complex sequences of protein interactions necessary to make them work. Aging happens because these sequences have only been tuned by evolution over a short lifespan. It just doesn't matter that much to most organisms' reproduction if their cells break down and stop working after a certain period of time. It can even be a good thing to have them die on purpose -- when cells just refuse to follow their molecular controls, we call it cancer.
Many of de Grey's proposed solutions would have us sweep aside these complex mechanisms, starting from scratch with new genetically customized replacement stem cells. That idea would limit to some extent what you would need to know about gene interactions -- it's like those custom kits that let you make a Ford Pinto look like a '26 Packard.
Perhaps the way to go, but is there some critical flaw? There are lots of interesting evolutionary reasons why aging should be an intractable problem, but it looks to me like many problems are swept away by the assumption that stem cells can be engineered to possess or lack any feature de Grey would require. The challenge may flush out somebody with a better idea of why it wouldn't work.
It will be interesting to see if anyone takes up the challenge. Personally, I wish somebody would offer a prize to show some anthropological research project is not worth serious consideration. Of course, with my luck it would be one of mine....