The answer to immortalty.

[Ibrahim90]

that does raise questions in my mind (I'm throwing these out there precisely so that they can be argued against--I lack sufficient imagination for this):

1-what about kids? if a person is immortal (even assuming such a person can be killed), that means there's little need to replace such persons. that means that even having one child a pair would lead to massive growth in population, even taking into account that many would not marry or have kids. we could in theory sterilize such people, but people are still going to die, and then require replacing. what then? do we unleash the Genophage? 

2-and of those kids, how can they have a future, if the older people won't just die? we see people who are in their 20's in the field of Geology who can't get a job because baby boomers won't retire and won't drop dead already. do we kick the youth down the curb?

[MrBogosity]

It just means we need to get off-planet. Although being immortal, there are a LOT of resources freed up from the medicine and other things that we won't need anymore.

[Dallas Wildman]

It just means we need to get off-planet. Although being immortal, there are a LOT of resources freed up from the medicine and other things that we won't need anymore.

Actually I think the opposite would be the reason why we're immortal.  We'd still have to make value judgments regarding whether or not we want to live longer.  Even if say our consciousnesses were transplant into entirely mechanical bodies (see Ghost in The Shell) they'd still require comparable maintenance.

In regards to children I myself not entirely sure about the incentives TO have them.  Closest thing I can think of is that they're merely a status symbol :p