China did, and does. China feeds itself and is on the edge of sustainability, and they know it. 
India does not. India cannot feed or sustain herself and must receive external help. 

As global warming drives climate change, and that affects agriculture, human population will change. 
We can do that voluntarily, or not. If nature dictates terms, they will be cruel. 

This is the lesson of metaphor in the Genesis story of Jacob, aka Israel. 
Israel in Egypt. 
Genesis Chapter 39
Aesop told it in the fable of The Ant and the Grasshopper. 
It was part of the argument between the conservative and liberal,
before the "modern conservatives" became so ignorant. 
Irony is there's almost nothing "conservative" about them. 
They're among the most wasteful, hedonistic people who ever lived,
and their "right to life" thinking is ... is ... I'm at a loss of words for it! 
Beyond ignorant, what ever that is. 

One certainty from increased human population and decrease of global ability to sustain the human population is political instability.
Wars to expand territory are one thing.
But war for survival is not only another thing,
it may be a natural population control that reduces population to a sustainable level within the boundaries we establish as a country. 

Thing is, we can control it up front with establishment of guide lines- laws, where we are sustainable
in the management of life,
Or we can breed and let nature take her course, where we have no control over it. 

BornToFarm wrote:

Why not attack the problem from the other end.  Use the Logan's Run approach and exterminate people after they have reached a certain age.   If the state raised all the children, then adults wouldn't be needed.  Extermination could occur at a fairly early age, perhaps 35.   No more retirement plans and expensive health care for old folks (those over 36).  Of course a certain number of elite folks would be needed to make sure things ran okay.  Those would be exempt from extermination.   Looks like most of us would be long gone.

/sarcasm off

==================================

**chuckle**  Well, that's an interesting take on it, but I doubt that those in power would EVER agree to it, so it looks like we'd more likely be facing restrictions on reproduction rights and crazy intense efforts in increasing the food supply.  I'm guessing that before the end of the 21st century, that humans will have figured out how to turn ocean water into drinking water effectively enough to eliminate that problem and that renewable power sources would predominate over our current fossil fuel thirst.

Thing is, what about radiation/nuclear pollution and climate change ??  Would those things have already eliminated millions of humans from existence ??

I'm thinking that it's the third world countries who are driving the population increases and so there is where humanity will need to FIX the issues causing the population explosion and then slow death of so many of them.

The earth, itself, seems to be able to function reasonably well at its current population, so if we solve the third world hunger & potable water situation, plus introduce effective birth control methods & health care, that they will resolve their own overpopulation just as the first world countries have managed. 

Then, there would be no reason to legally restrict family size since most families have two children, which only replicates themselves and doesn't increase the population.