On population (and Neruda)

So now it's Jeffrey Sachs who has joined those who claim for a reduction in birth rates... In fact, as reported by the New York Times, he argues in favour of a 2.1 ratio per family (and then he thanks his 3 kids).
I just have two words on that:
1) "Don't put the cart in front of the horse" (a free translation from Spanish). There's not one single country that has achieved development by restricting birth rates. It has always worked the other way around, so you don't need to worry: just help these growing countries to achieve development, then birth rates will take care of themselves.
2) Population is an endogenous variable... it's not that we are facing an "explosion" the planet can't sustain... Actually, we have reached this level of population because for the first time in human history we've been able to sustain it!: less wars, better medicine, more food. Now, I don't know if the world is able to sustain this level of population consuming at the same level that the US citizens do... but I know it can sustain the population to the level of consumption that allows them to live, and I dare saying, in much better conditions that most of their ancestors. The thing is that those conditions have bad press today, they are called poverty, and though it might be true that everybody would rather live in a better situation, I would not dare telling anybody that they would be more happy consuming more and having less children. I'd like to tell "developed countries" along with Neruda:

Ah you don't want to,
you're scared
of poverty, you don't want
to go to the market with worn-out shoes
and come back with the same old dress.

My love, we are not fond
as the rich would like us to be,
of misery. We
shall extract it like an evil tooth
that up to now has bitten the heart of man.

But I don't want
you to fear it.
If through my fault it comes to your dwelling,
if poverty drives away
your golden shoes,
let it not drive away your laughter which is my life's bread.
If you can't pay the rent
go off to work with a proud step,
and remember, my love, that I am watching you
and together we are the greatest wealth
that was ever gathered upon the earth.