It could become a problem with memory.

Information theory has done calculations on how much information storage capacity is in the humn brain, and the base their estimates on things like humber of connections between neurons, etc.

All the way back to the time of the ancient Greek philosophers, it used to be asked if the human mind was like a blackboard, which could be written on up to a point, after which it was full, or if it could absorb information indefinitly, and it's starting to look like the answer is... sort of both, depending upon life-span.

Current estimates are that, depending on the size of the human brain and the number of neurons in it (human brains vary in size from as litte as 950 cc's up to 1450 cc's, with an average of about 1200 cc's) it's theoretically possible for a human to learn all-out, like at the rate they were when they were a child, for 600 to 2000 years, after which point, in order for new information to come in, old information has to be dropped.

It means that within the context of our current life-span, our minds are basically limitless. You will never run out of capacity.

But... if life were extended to 5000 years... well... things from the earlier parts of their life could start getting fuzzy once they've passed the 600-2000 year mark.

It means that we'd probably have to start supplementing our brains with some auxiliary hardware... memory chips that can interface with the brain so we can keep a longer recall.

I was thinking about this very thing the other day, because I was reading Lord of the Rings. In that book, some of the races are immortal, and there are a few characters that are thousands of years old.

Assuming we'd live all those thousands of years in good physical condition and with full memory of all our years. then maybe in the best case we'd end up like Elrond:

-- Quote

The face of Elrond was ageless, neither old nor young, though in it was written the memory of many things both glad and sorrowful. His hair was dark as the shadows of twilight, and upon it was set a circlet of silver; his eyes were grey as a clear evening, and in them was a light like the light of stars. Venerable he seemed as a king crowned with many winters, and yet hale as a tried warrior in the fullness of his strength. He was the Lord of Rivendell and mighty among both Elves and Men.

-- /Quote

(The Fellowship of the Ring, Book II, Chapter 1)

Perhaps we'd live long enough to grow wise, and yet stay strong enough to actually put all that wisdom to good use.

Wow, this is a great question. Life insurance companies would do well in theory, but I think in practice they'd lose the majority of their customers and die. I think people would take MUCH better care of themselves and perhaps even become paranoid about it. Also, the birth rate would have to fall to almost zero pretty quickly or we'd have a whole plethora of resource and space-based problems. Talk about a conundrum!

If we remained fertile the whole 5000 years, then people who don't believe in birth control would over-populate our planet long before any of the people currently alive lived to be 5000.

Ever read what happens to baby rats when a rat cage is over-populated? It isn't pretty.