If it takes another 40 years to defeat aging through advances in biotechnology, the construction of therapies designed to prevent and repair the biological damage that causes aging, more than two billion people will die between now and then. Most of those fatalities will be caused by aging and the panoply of fatal conditions it creates, the end result of the fact that evolution largely favors faster adaptation for a species over greater length of reproductive life for individuals. Evolutionary pressures don't care about the endless suffering, pain, and destruction that they produce - but we, the product of those pressures, can care. Moreover, we can choose to do something about it.
Hence medical science, which is at its root the fight to defeat death and suffering. That said, much of our present society seems slow to come around to the realization that of course - of course! - the goals of medicine include the defeat of aging. Aging is just another of the many complex medical conditions that we should oppose and eliminate precisely because it causes pain and suffering. It should be up near the forefront of all research, as it and its consequences claim more than 100,000 lives each and every day.
But even under the most optimistic of scenarios, such as those in which the SENS program for rejuvenation biotechnology is fully funded starting tomorrow, billions will age to death before the research community can develop the first therapies capable of meaningful rejuvenation. There is something that can be done to address this issue, for all that almost as little effort is made here as for ways to cure aging: long-term preservation of the dead, accomplished in ways that prevent destruction of the fine structures in the brain that store the mind.
At present, the only way to preserve your mind on death is through cryonics, or low-temperature storage with vitrification of tissue. Legal obstacles make it harder than it needs to be to obtain a good preservation, and as noted above the long-standing cryonics industry is a thin thread rather than the mighty river of effort it would be in a more just and sane world. Billions have died since cryonics became a viable commercial product, of which only a few hundred have been successfully preserved.
They can wait out the coming decades, wait out the development of medical nanotechnologies that can reverse the processes of cryopreservation. Time is on their side in this age of rapid progress, assuming that the living community of enthusiasts and professionals can continue to ensure a long-term continuity of service.
A possible future alternative to cryopreservation is plastination, a different methodology for fixing a cell's structure all the way down to the finest details. No organizations analogous to the cryonics industry yet exists to offer plastination services, but that may only be a matter of time. Competition is healthy in any field of human endeavor.
Below is quoted a long article by a plastination advocate, published a few weeks back. It delves into some of the details regarding what exactly has to be preserved in the brain in order to preserve the mind, regardless of the method chosen, and where the uncertainties still remain. If you're interested in the scientific nuts and bolts of preserving the mind for the future, then you should find this quite interesting.
I should note in passing that this fellow sees the end goal of preservation as a record, not an individual in stasis: the preserved mind is a collection of data that can later be recreated as an active individual when the technology exists to run a human mind in software emulation. This is not a desirable goal from my point of view: a copy of you is not you, and restoring the preserved original tissue via suitably advanced medical nanomachinery is the desired end result. There are people who strongly favor one side or another or have no great care, but both end goals require the same quality of preservation. The data has to be there for a good restoration, regardless of how that restoration comes about, so (fortunately) philosophical debate over what constitutes personal identity has little impact on this stage of research and development, which can focus entirely on tangible, measurable issues:
To preserve the self for later emulation in a computer simulation, what brain features do we need? We can distinguish three distinct information processing layers in the brain:
1. Electrical Activity ("Sensation, Thought, and Consciousness")
These brain features are stored from milliseconds to seconds, in electrical circuits.
2. Short-term Chemical Activity (Short- and Intermediate-term Learning - "Synapse I")
These brain features are stored from seconds to a few days in our neural synapses (synaptome), by temporary molecular changes made to preexisting neural signaling proteins and synapses.
3. Long-term Molecular Changes (Long-term Learning - "Nucleus and Synapse II")
These are stored from years to a lifetime in our neuron's connectome, nucleus (epigenome) and synaptome, by permanent molecular changes to neural DNA, the synthesis of new neural proteins and receptors in existing synapses, and the creation of new synapses.
At present, it is a reasonable assumption that only the third layer, where long-term durable molecular changes occur, must be preserved for later memory and identity reanimation. The following overview of each of these layers should help explain this assumption.
The detailed sections of the article that follow that introduction defy easy piecemeal quoting, but it's very readable - dive in and see what you think.