Think the 'practically immortal' thing is just fantasy? Each of the approximately 100 trillion cells of the average human body replicates itself a set number of times before the increasing amount of errors inherent in copying prevent it from successfully doing so. That number is about 50 and it's called the Hayflick Limit. This is the actual process of aging. Scientists are currently studying this limit in an effort to revise and extend that limit. Success might mean you could literally stay physically younger longer.
As it stands now, with the increased knowledge we have of medical techniques and overall health practices, the average human lifespan has increased dramatically over the years. Back during the caveman days, you were considered old if you reached 20. As recently as the late 1800s, the average lifespan was 37 years. Back in the 1970s, the average lifespan was 70.1 years. Today, the average is 84 years for a man and 89 years for a woman. I keep telling my parents I'm going to live until I'm 150.
I will too.