The way the social dynamics would work is that everyone would have to get "immortality" and the total number of children at any time would have to be much smaller than today. Real immortality would literally require having zero fertility (or else a galaxy colonization program) for obvious reasons.
> The way the social dynamics would work is that everyone would have to get "immortality" and the total number of children at any time would have to be much smaller than today. Real immortality would literally require having zero fertility (or else a galaxy colonization program) for obvious reasons.
It depends. If by immortality you mean "each individual actually lives forever", then what you say is true. If it means "each individual could live forever," then you could have immortality and fertility... as long as you replaced death with literally murderous competition between the immortals for survival of themselves and their offspring. IIRC, that's part of the plot of The Mote in God's Eye (which has an alien society oscillating between relative peace and population-annihilating war).
I would define "immortality" (i.e., with the quotes, so not immortality) as the ratio of average or mean life expectancy to years-to-maturity. Today our "immortality" is ~4.4. If we lived to ~200 years with adulthood still starting at 18 we'd have an "immortality" of ~11. If we lived to 1,000 with adulthood starting at 18 then we'd have an "immortality" of 55.56.
We could fix these problems by lengthening childhood by the same factor as life expectancy, but then the new thing wouldn't be very interesting.
You'll probably also want cures and vaccines... for everything.
If you live forever, your chances of getting every un-fun STD out there, to say nothing of every flu-causing virus, are pretty good, and while Herpes won't kill you (hopefully), it might ruin your fun for the lion's share of your life.
