Today, we delve into the AAMC Content Category 9B. Let’s take an aerial look at demographic shifts: Malthusian theory vs demographic transition theory, population growth and decline, gentrification, and more!
These are not new terms for you for the most part. The tail end of this gets a little bit easier which is where we are right now. So we’re going to focus on the hardest of the hard. The rest of the stuff should be fairly straightforward, but you do want to still make sure that you’re going through it.
As always, I am joined by Phil from Blueprint MCAT (formerly Next Step Test Prep), the premiere place to get your full length exams. Save 10% by using the promo code MCATPOD.
Listen to this podcast episode with the player above, or keep reading for the highlights and takeaway points.
[02:41] Malthusian Theory
First, we have some big population stuff. Zooming out, we look at the populations in general. One of the first things here is Malthusian theory.“Malthusian theory is the idea that populations are going to keep going up and up and up. And we're going to overpopulate the world and then everyone's going to die.”Click To Tweet
It’s the idea that everyone is living a lot longer and everyone’s having more kids, the population is going to spike and we’re not going to have enough room. And this was a pretty common theory. It’s one that we’ve kind of accepted. But it’s probably not true at this point because as a society ages and gets bigger, you have smaller families.
Your parents probably had less kids than your grandparents did and their grandparents. In the past, the population seemed like it was going to be growing. But now they don’t. They tend to taper off.
You see very stable populations in very industrialized cities and countries that have stabilized over time.
And so the Malthusian theory is just this idea of this like sharp, exponential increase in population. And you still see population growth in some of the less industrial places. But that tends to taper off as you go through this.
This is actually leading to another theory, which is the demographic transition model.
[04:37] Demographic Transition Theory: Stage 1
The demographic transition model is kind of explaining why the Malthusian theory was incorrect.
The idea is that there’s a high fertility and high mortality rate. It’s like the advent of America and founding fathers.
For example, somebody needs help running the farm, so they’re going to have 15 kids and 12 of them are probably going to die just because that’s how it works. But the other three that are surviving will help them run the farm.
So this is like stage one of a society, it’s like pre industrialized.“You have very high fertility and very high mortality rates.”Click To Tweet
[05:26] Stage 2
But as society advances, all of a sudden, people die less because you have better medicine and better resources. People aren’t starving.“The mortality rate starts to drop off and the fertility rate still stays high for a while.” Click To Tweet
There’s this sharp increase in population when a society gets to this stage where the mortality rate starts to drop off a little bit, but the fertility rate doesn’t necessarily follow. And so everyone’s still having tons of kids. But there’s less death, which in general is good.
We start to see this spike in population where it starts to really exponentially increase as mortality rate is dropping.
[07:10] Stage 3
The fertility rate drops and so you start to have less children being born. The mortality rate is still low at this point. But the fertility rate is dropping. And even if it’s dropping, it’s still going to be higher than the mortality rate. There is an increase in population as the fertility rate is dropping.“This is very low fertility and low mortality rate.” Click To Tweet
[08:15] Stage 4
When you travel around Ireland, you would notice these farms that have been there forever and and the populations were still kind of growing. People are building new houses and things like that. The towns are expanding but the county is not overflowing with people and it’s just because the fertility rate drops.
So there’s a stable population over time. We still have some populations that are having very high birth rates. But we have very stable stuff now.
[09:02] The Theoretic Stage 5
But what happens if the fertility rate continues to drop? What’s happening in Japan when the population is actually shrinking year over year?
It’s something that the government is very interested in and concerned with. They would even pay for you to go on a date because people just weren’t dating and having kids.“Japan is like the theoretic stage five stage. It was not part of the original demographic transition model that was brought up.”Click To Tweet
Stage five is when the fertility rate continues to drop. This is the only stage out of the five stages where the population overall is decreasing.
[10:23] Summing Up the Demographic Transition Model
Stage one is pretty stable because fertility and mortality rates are both sky high. Tons of kids, everyone’s dying.
Stage two, less death. So the population starts to go up.
Stage three, the fertility rate starts to drop. But the population is still going up.
Stage four, it’s starting to stabilize because you have low fertility and mortality rates.
Stage five is this question mark of the fertility rate continuing to drop. So now, the population for the first time is starting to decrease.
[13:45] Gentrification vs Urban Renewal
Gentrification tends to be in a place where there’s like a stable population that is living there. They’re not super rich, but they’re making ends meet. And it’s an okay place to live.
Whereas in urban renewal you tend to have like, graffiti and crumbling buildings and everything falling apart. It’s not stable. It’s declining and it’s this declining population. You come in and then you make it nice.
If it’s declining and becoming worse than awful and dangerous, then you fix it up. That’s urban renewal.
If it’s just a stable population that you’re just swooping in here and making it too expensive, then that’s going to be more gentrification.
The connotation is kind of important but also just kind of like figuring out like what, when is it one and when is it the other.
[14:45] Population Pyramid
This is looking at how populations change over time. The bottom of the pyramid will show how many boys and girls are on this like zero to one age group and then up. And then one to two and then two to three and then three to four and it keeps continuing up this way. Now generally, these should look like pyramids because there’s not a lot more 60 year olds born every year and people die off.“In general, the top should be narrower than the bottom, which is wider. But we don't always see that.”Click To Tweet
America’s got a very interesting population pyramid because of the boomers. We have this stable or even maybe declining kind of looking like a pyramid and then it will jet out.
There’s also some special terms. Like if you go down about 20 years from the boomers, it kind of bounces out again. And so it’s like a second thing, it’s not quite as pronounced as the boomers, but it’s still there.
So this is after the boom, like 20-30 years younger. This giant population in this certain age group tends to have kids all at the same age. We call this an echo. So it’s the boom and then the echo.
It’s an echo generation where you see this go out and then narrow in and then come back out again. This is where you see a lot of millennials overall. Their parents are all boomers.
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