Demographic transition models

[laczlacylaci]

I might just be burnt out from studying today, but I cannot interpret this graph.
So the question asks at which point would we see the lowest population.
Kaplan's key made is seem like within these models, populations will always increase, which is obviously not always the case.
1) Why does A have a lower population than D?
Is it because that within B and C, the birth rates increased the population more than A (the baseline), so D>A, population wise.

2) Can we assume that when birth rate is higher than death rate, the population will always be increasing, not declining?

3) What if the graph continued, and pt D ended looping to the same level as A. (Overall, looks like a U), would it still be the same answer, A=lower population, because birth rate is still higher than death rate?

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[wizzed101]

You have to read about population growth and economic theories.

A is the case of developing nation: poor healthcare and low standard of living/technology which leads to making babies the more entertaining activity which also satisfies the needs for labor.
D is the case of post-modern societies: good healthcare keeps people living longer and higher standard of living makes ... fewer babies (there are various explanations for this; personally, I think that having a tradition family is not crucial of mental well-being anymore).

Edit: And population only drops when death rate exceeds birth rate. According to the graph, that never happened.

 

[theonlytycrane]

1. Between A-B, births and deaths are kind of even-ing each other out. Between B-C, death rates drop below birth rates -> population increases even though the relative numbers drop. They kind of even each other out again from C-D, but the period B-C when more births occurred than deaths increased the population.

2. Yes.

3. Regardless of where pt D. is set to, if the birth / death rates even out again the answer wouldn't change. The B-C part is the key to why the population increased. The answer *might* change if they put death rates above birth rates at pt D., but then it would be hard to tell what the answer is without markings on the Y-axis.

Other than the graph, know the term 'demographic transition model'. In a crappy economy / country, people are poor and get it on a lot but die quick. As an economy develops, people probably still get it on but maybe use protection and live longer.

 

[laczlacylaci]

'get it on a lot' lmao.
thanks!