Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Misunderstanding Malthus’ mistake

andrewbatson.com

Post reply on HN
Print view View original

21–30 of 32 posts

Re: Misunderstanding Malthus’ mistake

#21

Post by Kim_Bruning »

wombatmobile wrote: post #5
Kim_Bruning wrote: post #3

Here I was hoping that this would be about Verhulst's improvements to Malthus' work. Verhulst's logistic equation still gets used today.

If you were to state what Verhulst’s insights were, you might start a conversation about this.

The original conversation happened almost 2 centuries ago I think (1830's). But sure!

I think we throw away the baby with the bathwater when we say "Malthus was wrong". I think it's better to say "Malthus inspired the beginning of an awesome idea".

Malthus' original idea was where he plotted population growth and food production in the same graph. When the 2 lines crossed, that's bad.

That's obviously not very realistic, but actually he had the gist of it; it just needed a bit of refinement.

Not much later, another Belgian by the name of Verhulst did indeed improve on Malthus' model. He came up with a formula where at first the population grows exponentially; and then later it slows down before it reaches the limit (carrying-capacity). In Verhulst's model, you don't have a catastrophic line-crossing.

At that point, you basically have an actual Minimal Viable Product that you can use to predict and think about real-world population dynamics, and a whole lot more besides.

Over the last two centuries people have built a lot of discoveries on top of that.

This Veritasium video is about one small (but awesome) bit of that: https://www.youtube.com/watch?v=ovJcsL7vyrk

It's a good thing not everyone thought Malthus was (completely) wrong!

Re: Misunderstanding Malthus’ mistake

#22

Post by Keysh »

tuatoru wrote: post #17
littlestymaar wrote: post #2

> Something clearly operated to keep human population in check before its explosion over the last couple of centuries. But it was generally not starvation. The real problem is that population growth begets population density, and population density, in the absence of sanitation, antiobiotics, and other checks on infection, begets disease and death That's an interesting opinion, but how does that model explains why ea…

When people are chronically malnourished and undernourished, they succumb to one of the many diseases swirling around. Infectious diseases or deficiency diseases or parasites. Periods labelled "famines" were not all that common, but much of the population was living in a sub-acute famine much the time, primarily for political reasons (power imbalances, unelightened decision-makers). > how does that model explains why…

> until the 20th century, with Beijing* as the primary exception, big cities were in Western Asia, North Africa, and Europe > Why did rice-growing areas have villages while wheat areas developed cities?

I'm sorry but that's simply untrue. There were lots of cities in premodern China. Urbanization probably got started earlier in the Near East, which is why you get early large cities there, but even in the list you link to, from ca. 1000 BC on there are basically always one or more Chinese cities in the list: Haojing, Luoyan, Xiadu, Chang'an/Xian, Nanjing, Kaifeng, Hangzou, .... (And this is ignoring other large cities that were never the largest like Guangzhou.)

(Beijing doesn't become really significant until the Mongol Yuan dynasty makes it their capital in the 13th Century.)

Re: Misunderstanding Malthus’ mistake

#23

Post by wombatmobile »

Kim_Bruning wrote: post #21
wombatmobile wrote: post #5

Earlier quoted context omitted.

If you were to state what Verhulst’s insights were, you might start a conversation about this.

The original conversation happened almost 2 centuries ago I think (1830's). But sure! I think we throw away the baby with the bathwater when we say "Malthus was wrong". I think it's better to say "Malthus inspired the beginning of an awesome idea". Malthus' original idea was where he plotted population growth and food production in the same graph. When the 2 lines crossed, that's bad. That's obviously not very realis…

Hmmmmmmm! I didn't know about Feigenbaum's constant.

That is interesting and mysterious...

Re: Misunderstanding Malthus’ mistake

#24

Post by Keysh »

duxup wrote: post #7
littlestymaar wrote: post #2

> Something clearly operated to keep human population in check before its explosion over the last couple of centuries. But it was generally not starvation. The real problem is that population growth begets population density, and population density, in the absence of sanitation, antiobiotics, and other checks on infection, begets disease and death That's an interesting opinion, but how does that model explains why ea…

The article does say that Rome required some level of constant migration into the city to maintain it's population. I can't speak to how true that is but it might explain the population numbers.

I think that's perhaps rather generically true for premodern times. I've seen estimates of mortality rates for medieval England that have cities consistently higher than rural areas, so you'd have to have migration to the cities.

Re: Misunderstanding Malthus’ mistake

#26

Post by pwinnski »

bernardv wrote: post #25

That very first sentence is very misleading. Malthus was not wrong - he was right given the set of assumptions made at the time. There is a difference.

The article goes on in some detail to make the case that even by your belabored definition of wrong, Malthus was wrong. It was never—or rarely—food that limited human population, but disease.

Re: Misunderstanding Malthus’ mistake

#27

Post by gumby »

littlestymaar wrote: post #2

> Something clearly operated to keep human population in check before its explosion over the last couple of centuries. But it was generally not starvation. The real problem is that population growth begets population density, and population density, in the absence of sanitation, antiobiotics, and other checks on infection, begets disease and death That's an interesting opinion, but how does that model explains why ea…

Sanitation practices may have been more developed in the denser regions of Asia than they were in post-Roman Europe.

Anecdotally it feels that way (bathing, certain food handling and disease rituals) from reading historical accounts. I have a parent from each and when they talked about their childhoods (1930s and 1940s), even through war, the differences are stark. But I’m hardly a scholar so this is anecdotal.

Re: Misunderstanding Malthus’ mistake

#28

Post by 1123581321 »

wombatmobile wrote: post #23
Kim_Bruning wrote: post #21

Earlier quoted context omitted.

The original conversation happened almost 2 centuries ago I think (1830's). But sure! I think we throw away the baby with the bathwater when we say "Malthus was wrong". I think it's better to say "Malthus inspired the beginning of an awesome idea". Malthus' original idea was where he plotted population growth and food production in the same graph. When the 2 lines crossed, that's bad. That's obviously not very realis…

Hmmmmmmm! I didn't know about Feigenbaum's constant. That is interesting and mysterious...

That’s all you have to say? ;)

Re: Misunderstanding Malthus’ mistake

#29

Post by esarbe »

Considering that our predatory rampage of resource extraction has brought our ecosystem to the edge of collapse, I'm not convinced that Malthus was wrong.

Let's revisit this again in 50 years when we've stabilized our population and don't push earth day forward with every year.

Post reply on HN