First, watch this video from Juan Enriquez's latest TED talk. It should give you a good idea of where we are in understanding life as a set of mechanical systems. Such understanding has eluded us for ages because as Douglas Adams put it years ago 'We have always preceded from the idea that to learn how something works, we take it apart. However as soon as you take apart a cat, the first thing you have on your hands is a non-working cat. Life is an order of complexity so far above our understanding that we have classically assigned a mystical explination to account for its existence.'
This holds true to the idea that religion is just a standing explanation for things we don't fully understand yet. It's a placeholder, like the incomplete special effects on the leaked version of the new 'X-men Origins: Wolverine' movie ... or so I'm told. However our science has now progressed enough that while we don't understand conscious thought and all this sentience crap just yet, we do understand how cells and DNA interact and function like the hardware and software of a computer (respectively). We can, and indeed have manufactured life at the cellular level, as well as what amounts to 'replacement parts' for our own bodies. Such advancements have only been possible because of our understanding of how life functions at the most basic level.
This understanding began with Darwin and On the Origin of Species, and really got going with Watson and Crick's (slightly stolen) discovery of DNA. But our approach was still governed by the idea of an intelligent and deliberate creator. A 'top-down' system of complexity.
[there is a famous explanation of the universe that has turtles 'all the way down' but logically, a universe created by a god of some kind raises the question of the god's creation, and leads one to the conclusion that in such a system there are 'gods all the way up']
But with the advent of modern computing and the way in which software works, we began to see that all the marvelous complexity and beauty around us could be explained from a perspective of 'bottom up' design. No matter how complex the computer program, it all begins with adding 1 and 1 and testing the result. And then doing it again. 'Ones and zeros' as my father says whenever I try to explain a complex technological concept. With an observable model like software, we can see that very very simple actions, iterated many times over, can lead to very very complex results.
This ideological bombshell has not quite created the stir that it rightfully should, but it has changed the way that I look at the world, as well as the way any fervent fans of Douglas Adams surely have. (if this whole things smacks of his speech to the Cambridge Scientific Society it's because its completely riped off from it) So the 'miracle' of life has lost its mystic explination. As its put in the above video, 'life happens.' Software and Hardware, just following a set of rules and acting as they always have.
We are just beginning to be able to understand and modify life at not only its most basic level (cells) but also at the tissue, and almost organ levels. Just how we decide to modify or even replace these particular aspects of ourselves and other living organisms, I'll cover in another post. For now just let this information stew in your mind for a little while.
We no longer need to rebuild him. We have the technology. We can regrow him. Make him better, if he wants, faster, if he so chooses, stronger, if he sees the need. Or we can bring him back to just how he was before.