In practical terms, global population would go berserk unless this sudden spurt in longevity was accompanied by a massive die off and much slower reproduction.
If the length of childhood and puberty remained the same, then you have to wonder what the average 500-year-old would remember about his or her childhood.
Furthermore, think about the amazing changes people who lived for a hundred years experienced even a century ago. A person who lives for 500 years would witness unbelievable changes. I would think that would in fact be somewhat traumatizing.
Would people still work forty years before retiring for the next 700 years? Or would they work for 700 years? Would they switch careers every century?
While the chance to live for more than 500 years sounds exciting, I suspect it could actually be a little scary. If people still succumbed to disease and injuries, think of all the friends and acquaintances you would lose over a period of 700 years. Think about all the people whose lives are impacted by poverty or drugs. Would they be mentally disabled or homeless for 700 years?
And what kind of health would people over 100 years old have? If they were healthy enough to play soccer for 500 years, then their joints would wear out long before that. Fortunately, medical science can replace knee joints.
It's hard to say how such a revolutionary change in aging would change our perceptions on mortality. People would obviously still be mortal, and they would obviously know they're going to eventually die - and they could possibly die from disease or an accident the next day.
On the other hand, a 500-year lifespan would give a person more than enough time to at least pretend to gain immortality by writing 500 books, building elaborate tombs or whatever.
It's interesting to speculate on how intelligent a person might be after 500 years. An active learner might become so smart he or she could no longer relate to people less than a hundred years old, and vice versa.
On the other hand, this could ironically result in sort of a throwback to the past when people respected their elders as reservoirs of knowledge. Today, little kids often seem to pick up on computer skills and social networking conventions faster than adults.