
The Great Hanoi Rat Massacre of 1902 Did Not Go as Planned (2017) - pepys
https://www.atlasobscura.com/articles/hanoi-rat-massacre-1902
======
IanCal
I use this as an example of why we need to be careful to think about what
we're optimising for in ML. They wanted to reduce the number of rats, but
incentivised increasing the number of rat tails.

Do your performance measures correspond directly to things you care about? Are
there ways of optimising the number while hurting something that matters to
you? A good example to me is Google marking a picture of a black couple as
"gorillas" \- to a training algorithm that can easily be counted as a single
wrong answer equivalent to any other when it is actually very significant.

Edit - this is the same for optimising any KPI, but ML is a case where your
optimiser has no wider context and so there's more surprising cases. Worth
thinking about overall though, what are you rewarding?

~~~
mikeash
See also:
[https://wiki.lesswrong.com/wiki/Paperclip_maximizer](https://wiki.lesswrong.com/wiki/Paperclip_maximizer)

------
diego_moita
Something similar happened in Rio de Janeiro under the supervision of the
epidemiologist Osvaldo Cruz during the very same year.

Rio was infested with bubonic plague and yellow fever. Oswald started a
campaign to get the city rid of mosquitoes and rats including the same idea of
buying rats from the population. The result were the same, people began
importing rats from neighboring towns and breeding them at home. He later
switched the focus into hygiene and sanitation.

Cruz is also famous for making vaccination mandatory in Brazil, a decision
that led to the infamous Vaccine Rebelion in Brazil:
[https://en.wikipedia.org/wiki/Vaccine_Revolt](https://en.wikipedia.org/wiki/Vaccine_Revolt)

------
Smaug123
The general name for this phenomenon is the Cobra effect:
[https://en.wikipedia.org/wiki/Cobra_effect](https://en.wikipedia.org/wiki/Cobra_effect)

~~~
alehul
From the article:

> These days, the Great Hanoi Rat Massacre is mostly cited as an example of
> the “Cobra Effect,” an economic theory about how incentives, in a complex
> system, can lead to perverse, unintended consequences. Sometimes, it’s
> trotted out as argument against government intervention of any kind—but Vann
> says that that kind of misses the point.

------
borroka
Michael Vann wrote this recent book on the Hanoi Rat Hunt

[https://global.oup.com/ushe/product/the-great-hanoi-rat-
hunt...](https://global.oup.com/ushe/product/the-great-hanoi-rat-
hunt-9780190602697?cc=us&lang=en)

------
sonnyblarney
The moral of the story is wrong.

If people are going to go ahead and cheat the system en masse, no system of
incentives will ever work properly and they will languish.

Civil society requires us to generally do the right thing, most of the time,
because there's ample opportunity to be shortsighted and cheat.

FYI Here's how Alberta git rid of rats [1], though I don't see any mention of
rewards either, more of a publicly managed awareness program with hired pets
killers.

[1] [https://www.alberta.ca/history-of-rat-control-in-
alberta.asp...](https://www.alberta.ca/history-of-rat-control-in-alberta.aspx)

~~~
yborg

      "Buildings are occasionally moved or torn down, and in some cases, rats are dug out with a backhoe or bulldozer."
    

Alberta really hates rats.

------
chinhodado
I am interested in knowing what happened after. Did they just give up on the
rats? What do cities around the world do to control the rat population?

~~~
protomyth
You end up hiring "professionals" that will actually keep the spirit of the
agreement not just the letter (contracts do wonderful things in the modern
world).

Although, I do know of one case where the locals gave up on a building
(exterminator said no, the cats ran for it, and hantavirus was a concern).
They cut a trench around the building, filled it with gas, lit the trench up,
then set the building on fire. It was a bit horrific. They built another
building on the same plot but not the exact same place.

~~~
pixl97
Reminds me of that hoarders house in the US, that was so infested with
cockroaches the fire department built a fire pit around it and burned it to
the ground.

~~~
protomyth
Its a valid strategy, especially when you are dealing with disease or some
insects. It provides a bit of a training opportunity and sometimes there just
isn't any hope.

If for some odd reason, you are doing thing yourself (why?!), do remember the
order: dig trench -> fill trench -> ignite trench -> ignite structure. Do the
order of the last two step wrong can result in a very scary video on YouTube.
Do not have squeamish people there with you. Keep plenty of firefighting gear
near.

------
mimixco
Interesting! Whatever you optimize for in human (or machine) behavior is what
you get.

------
carapace
“To watch out for programs being created in situations where where the
arrogance is so strong and the power differential is so intense that evidence
can be ignored.”

~historian Michael Vann

------
simonebrunozzi
TL;DR: rat hunters were cutting rat's tails to obtain the reward, leaving rats
alive to let them multiply.

