Death

The genome is immortal, apart from it's liking for recombination with similar genomes and a very low rate of mutations. The cell-line is immortal. It's brains and bodies that die.

Look up senescence- biological aging/deterioration. This is an active area of research as to why life deteriorates and eventually dies. It may not be a complete answer, but in short the basic idea is deterioration/aging is caused by genes we all carry and the reason natural selection doesn't select against these genes is because they generally don't express/become active until after reproductive age when the genes have already been passed on to the next generation.

Also related to this, look up mutation accumulation theory of aging....Numerous other genetic and environmental factors can be involved making the subject an interesting but complicated field...and the possibility that if these deleterious genes could somehow be removed from the human genome lifespans could increase dramatically- then you just have to make sure you don't get hit by a bus

I like the bus part, it's good to know that we always have an exit plan : ))

again, thank you for the insight and direction!

i was reading this 2 weeks late..everyone gone home now..but the immortality thing reminded me of the guy who boasted he had used the same broom for 30 yrs, but he'd changed the handle dozens of times. Thats an analogy, or something.

How many "dozens of times" did he change it?  I'm sure that would make a difference on the anal ahh geee. 

That actually reminds me of the time I pick pocketed this same person "dozens" of times.  When I say dozens, I mean exactly 29 times. So, it was at least 2 dozen times.