Prehistoric migrations into South Asia

A new paper here, its abstract, and commentary from Rudradev on BRF:

A diffusion based study of population dynamics: Prehistoric migrations into South Asia
Mayank N. Vahia, Nisha Yadav, Uma Ladiwala, Deepak Mathur
Published: May 11, 2017
https://doi.org/10.1371/journal.pone.0176985

India: Total Fertility Rate

A United Nations document "World Population Prospects - The 2006 Revision" (PDF file) has India's total fertility rate (TFR, number of children per woman, projected, "medium variant")

2005-2010: 2.81
2010-2015: 2.54
2015-2020: 2.32

The "World Population Prospects, 2015 revision"  has revised these to:

2005-2010: 2.80
2010-2015: 2.48
2015-2020: 2.34

The Indian National Family Health Survey (NFHS) has these total fertility rate figures.

NFHS-3 (2005-2006): 2.7
NFHS-4 (2015-2016): 2.2

As you can see, NFHS-3 is right in the middle of the UN figures; but NFHS-4 shows TFR has fallen faster than the medium-variant projection.

Per the 2005 UN document, India's 2050 population ("medium variant") was projected to be 1.658 billion,  per the 2015 document 1.705 billion.

In the "low variant" of UN's 2015 population projection, India's TFR 2015-2020 is 2.09, and  its population in 2050 is projected to be 1.509 billion.

Thus the "low variant" population projection is still a viable lower bound for India's population;  the "medium variant" is an upper bound that can be tightened substantially, I think.

But we also see that projections just ten years out can be wrong, so perhaps more useful is what India's 2021 census will show.  The low variant is 1.387 billion; the medium variant is 1.404 billion.  The difference is about a Netherlands' worth of population.

UN World Population Projections

This is from 2015: (PDF file)

Rogoff: "....global population in long-term decline..."????

Kenneth Rogoff here:

Some say that governments did not do enough to stoke demand. Although that is true, it is not the whole story. The biggest problem burdening the world today is most countries’ abject failure to implement structural reforms. With productivity growth at least temporarily stuck in low gear, and global population in long-term decline, the supply side, not lack of demand, is the real constraint in advanced economies.

Perhaps he means the "global population of the advanced economies" (whatever that means)?
Even restricted to what the UN calls "more developed regions", a population decline begins in 25 years from now, if it ever does.  It is hard to imagine that quarterly-results-obsessed US industry is thinking that far ahead.  But I'm not an economist, let alone a very sharp and respected one.

From a United Nations website: