Do you really want to live forever?

Thought Experiment. 

Medical science finally gets telomere-repairing gene therapy right, and we all can now live till age 500+, in perfectly healthy bodies. What happens to the world?

Step One: Population Bomb. Natural death rate will fall to zero, and given that everyone's fit and healthy, and likely to remain so for a long time, children being born will go through the roof. And their children. And their children. For over 20 generations, and let's not forget the original parents are still breeding. Exponentially explosive growth doesn't remotely cover it, this shit is nuclear. 

"They won't be that stupid", you say? Maybe the countries and populations with easy, affordable access to birth control won't, but that's only the upper layers of first-world countries and the very narrow upper layers of the rest, or in other words, around 1-5% of the population. For the rest, it's literally bang, and boom. 

Step Two: Resources Vanish. In less than a generation, we'll be hellishly overcrowded. It's not just a case of people having 1-2 kids in their prime; their prime is now nearly infinite. They can keep earning for decades, they think, so it;s a new generation every few years. Jobs, education, space, food, and water become scarcer and scarcer. 

Step Three: Economies of Scale. With family sizes exploding, and each generation competing with forefathers and ancestors for the same place in the sun, the individual family unit will be too inefficient; there'll be a movement into joint families, then commune-style setups. 

Step Four: Total War. With the economies of scale in place, each community or extended family unit is an effective, organized force, with its own supply chains and specialist systems. What used to be bad blood and feuds, will have the potential to become all-out battles, especially if the prize is twice the living space and resources up for grabs. And with that many people around, human life will look cheap. 

Step Five. The Recession. As life becomes more and more brutal - and we're still talking about a time maybe a hundred years ahead - people will start realizing that a controlled approach is the only way this will work. And since children are no longer the means for you to control your resources and wealth over time - you can do it yourself - they'll lose all meaning and just take on nuisance value. Infanticide, indoctrination, slavery. 

Meanwhile, on the other side of the world...

The more developed countries will see the spectre of a population bomb sweeping out from Africa, Asia and consuming everything in its path. If they can hold themselves together for even a generation, the enemy will have starved himself into a non-threat, and in two generations, will be a collapsed, shattered economy - ripe for the plucking. Then will begin the real horror of systematic invasions, genocides, exterminations. They might be holding themselves together, but they're still bursting at the seams, and the need the oil, water, farmland. 

A first thought that comes to mind is that ecology will be devastated, but that may not happen. Societies crumbling under the weight of their populations will have access barely to an industrial-age technology, while the more developed will be forced into long-term, ecologically sustainable green tech - after all, they're still going to be around, so anything that turns bad in 50, 100 years will not be wanted. And nations that are sparsely populated but technologically developed will have a huge headstart in this. As long as they can repel the raiders. 

Don;t confuse this with eco-friendliness, though. If there's something that can be harvested with no long-term impact - thought it might wipe out entire species - it will happen. 

So there's likely to be a massive expansion into oceans, space, and underground, to open up new areas for expansion and maintain a technological edge, at least in the first world... and then a few centuries of fighting to keep those from falling into the hands of the starving millions. 

And this is something straight from Larry Niven - with a longer life, will people be more careful? Take fewer risks? Or will the ravaged world they now live in, allow the luxury of a low-risk life? 

Preservation through Overtaxation

Given the catastrophic fallout, the drug is not likely to be available easily. Very restricted, very high-priced. So obtained only by the very few - who then continue to hang tightly to their positions of wealth and power. 

Very strong urge to build long-lasting structures to maintain the status quo. Strong opposition to any kind of systemic change. 

Extend this to political power positions, and you see not just Dictator-for-life, but for several of his subject's lifetimes. Within a lifetime, revolutions will become impossible, and he will become a living god within his indestructible castle. 

So will begin the era of assassinations, political games, and power plays between the long-lived players. 

Who else will have access? The ones who took it illegally. It's going to be a very, very expensive drug. And the criminal syndicates and families will become unshakeable. 

End result - 

Warlords, tyrants, politicos, and kingpins - and merchant princes - living in a unchanging, stagnant world, full of ignorant serfs, assassins, starving slaves, destroyed biodiversity...