If we could limit children to two per couple. What would the population stabilise at?

Question

and how long would it take, given that the present population is about 6.0Bn. Is there a formula in demographics to calculate this?

Answer 1

It's correct that a limit of two children per family would cause the population to very slowly decline for the reasons mentioned. But that avoids the question.

What you want is not a LIMIT of two, but an AVERAGE of two. (Actually, what you want is a "total fertility rate" that matches the "replacement level fertility" of about 2.1 or 2.2)

Nitpicking aside, some adults will have no kid or one kid, most adults will have two kids and some will have more than two to make up for the people who choose to have fewer. At that point, the population will stabilize.

In the real world of 2007 the average number of kids in practical terms is still greater than 2.2 and there are very large numbers of young women who have not yet had their babies (that is, there are far more young women who will bear babies in the next ten years, than there are old women who will die - so the population will increase). The world population is still aiming upwards.

It is pretty hard to predict exactly how the population will grow, because we do not know how rapidly the average family size in the less developed countries will decline. And we do not know how many kids women in the next generation will actually bear.

It seems pretty likely to me that we will have over 9 billion people on the earth in about 50 years from now.

Answer 2

You haven't included sufficient data in your question to calculate the answer. Firstly, the birth rate (fertility rate) in 2005 was only 1.79 children per female. Consequently, if you managed to achieve exactly 2.00 per female, then the population would rise.

However, you have to factor in immigration. If immigrants were limited to 2.00 children, then the rate would stay the same, but the number of children would rise. This assumes that immigration always exceeds emigration.

Then, there is the wild card of an epidemic such as bird flu which could kill weaker people such as children. However, given the facts, I would say that the answer to your question is probably that the number of live births would increase.

Answer 3

If couples were limited to two children, the population would theoretically remain constant at its present value, because people would have exactly enough children to replace themselves. In actuality, though, the population would creep steadily upwards as life expectancies rose. Also, it would be necessary to create an allowance that a couple could have more children if any of their original children died before reproducing. Otherwise, the population would actually fall as mentioned, due to deaths throughout the early life of children.

Answer 4

There are lots of formula in demographics!
Population won't stabilize, really!
Calculating it's a thing (statistics, actually), and true life, another....
Statistically, the population would remain at actual number, or decreasing a little bit...

Answer 5

This has a term this is extensive-unfold as "0 inhabitants administration". i think of without making it a harsh regulation it would desire to easily study to teach people. some individuals are in basic terms no longer likely to care and could the two by no potential have toddlers or bypass directly to have 12. a lot of folk do no longer have faith in delivery administration, abortion, or adoption this is may be puzzling to enforce this "coverage". the only ingredient we are able to do is teach ourselves and attempt to make stable judgements with reference to the way forward for the two this planet and our toddlers.

Answer 6

It wouldn't stabilise. It would keep falling until the human race was extinct. 2 isn't enough to keep the population stable, as many children die during childhood before they have themselves produced children. Also, not everybody forms couples and has children.

Answer 7

Well, Gnomon beat me to the right answer. Dang!

Answer 8

yes, google it