In general, human beings would like to live longer. I’m sure as a matter of practicality there are plenty of exceptions; but let’s put it another way: Most human beings don’t want to die.
 
Some people will argue about this all day…and into the next, as if they would live forever. However, if you’ve been paying attention to the gerontology news, heh, you’d know that there are many reputable scientists – not all of them old – who believe we will be living longer. This will be more than the ongoing general improvement in medicine and life conditions; it will also be the result of deliberate treatments and activities.

Research over the past couple of decades has begun to reveal information about how we age at the biochemical level. Quit smoking, eat less, exercise more – all good things to do if you want to live longer; but until recently we weren’t sure how this played out in the molecular chemistry of our body cells.
 
One of the more interesting findings of the past decade was that diet reduction – eating like 30-40% less than ‘normal’ – lengthened the lifespan of many organisms (mice and fruit flies in most studies).  
 
Fruit flies get old too, of course. Many of their biochemical processes, including those involved with aging are similar to those of humans. That makes fruit flies interesting for laboratory study of aging. (Other advantages: fruit flies multiply quickly…many generations in a short time, they’re inexpensive and relative easy to maintain, and except for U.S. Senator John McCain, they’re not controversial.) While results with fruit flies should be viewed on their own merits – without overeager extrapolation to humans – it’s not unreasonable to think in terms ‘suggestive’ of possible human processes.
 
One thing researchers have been able to tease out of fruit fly longevity studies, is that while giving them less to eat (close to starvation, actually) makes them live longer, it also makes them breed less. This trade-off does make evolutionary sense. Lean times are probably not the best for raising big families, so live longer to breed another day. Something like that.
 
The next question was whether a restrictive diet was what did the trick. In short, it wasn’t. The findings of one study (Max Planck Institute for Biology of Ageing) showed that it was really the lack or abundance of amino acids that were critical. In fact, it was one amino acid – methionine. Bring up the levels of methionine and breeding goes up (to a point). It was also shown that there wasn’t necessarily a trade-off between living longer and breeding. Manipulating methionine along with balancing other amino acids could improve both – at least in fruit flies.
 
Another study, at the Massachusetts Institute of Technology (USA), indicates that certain proteins are instrumental in coordinating the effect of diet on longevity. In particular, a class of protein called sirtuins, brings about the effects of calorie restriction on a brain system that controls growth and influences lifespan. Further research is underway to determine how, at the biochemical level, sirtuins affect what is known as the somatotropic axis – those parts of the brain and endocrine system, which send reproductive oriented messages to the other cells of the body.  
 
The hope in these researches, of course, is to find specific substances such as proteins or amino acids that can be used to directly manipulate the aging process. That may or may not happen, if only because the studies are mostly with animals other than humans. The translation to human biology might not work. At the least, however, research into the biochemistry of aging is revealing that while complex, there are discrete elements that play important roles and these elements may be something that we can, eventually, influence.