It's possible that we could change a human gene and double our life span. I don't know if that's true, but we can't rule that out.
It is unlikely that changes in telomeres are influencing the lifespan of the worm. That is because telomeres only shorten when cells divide. Most of the cells of the worm stop dividing when the worm becomes an adult.
There are lots of different strategies that an animal can use to survive. What a worm does is try to convert food into worms as soon as possible. In three days a single worm produces 300 progeny. So why put your resources into developing if you can make a brand-new worm in no time at all?
The hope is that if we can increase youthfulness, we can postpone age-related diseases.
Age is the single largest risk factor for an enormous number of diseases. So if you can essentially postpone aging, then you can have beneficial effects on a whole wide range of disease.
With worms you can just change genes at random and see if you can find a mutant that does what you want it to do.
