[thaumasiotes]

> and Ireland's population hasn't recovered since.

This is a somewhat amazing claim. It's bizarre for a population bottleneck in 1852 to have lasting effects (on the size of the population) over 150 years after the cause of the bottleneck ended, much as I don't expect the number of mosquitoes in 2014 to go down no matter how many I manage to kill in 2013.

Census records [1] tell a very interesting story:

Ireland's population apparently peaked in the 1840s at 8.2 million people. By 1851, that had crashed to 6.6 million, and by 1861, 5.8 million. By then it seems safe to assume that the famine was over (for one thing, it's supposed to have ended in 1852), but Ireland's population kept declining into the 1920s and then stayed flat for another 30-40 years (population in 1961: 4.2 million), whereafter it started growing at a fairly quick (indeed, accelerating) pace. The 2011 census shows 6.4 million people.

I can't think of a reason for a famine in the 1840s to cause the population to fall from 4.7 million in 1891 to 4.2 million in 1926. I have to wonder if what drove the numbers wasn't the famine but the demographic transition. Any idea when that took hold in Ireland?

My other guess would be that the mass emigration of the 1840s-50s created a long-lasting easy pathway for Irish to emigrate to the US, and that this proved so attractive that the population stayed low even in the face of high birthrates. But I wouldn't call that a misfortune for the people of Ireland.

[1] http://www.nisra.gov.uk/Census/Historic_Population_Trends_%2...

EDIT:

It's probably worth noting here that 30 million people recorded their ethnicity as "Irish" in the 2000 US census.

[simias]

This is a very interesting comment but I feel the need to point out that your comparing the Irish population to mosquitoes could be perceived as a bit harsh!

Not to mention that if you actually manage to reduce the mosquito population by 20 to 25% (as the Great Famine did in ireland) I'm sure you'll see an impact on the following years.

[thaumasiotes]

Harshness is definitely not intended. I was hoping to evoke people's direct lived experience of (1) killing lots and lots of mosquitoes, and then (2) failing to notice any impact at all on the prevalence of mosquitoes. Unfortunately, choosing something with a reproductive cycle that humans can have gut-feeling level experience with restricted my analogical options to, um, "undesirables". The point I'm trying to make is that they're both living systems, and living systems of all types grow incredibly quickly.

Look at this another way: over the last 50 years, the population of Ireland grew by 50%. Over the 50 years before that, it grew by negative three percent. And the famine happened 50 years before that. It seems very difficult to explain the 1911-1961 performance in terms of the famine.

> Not to mention that if you actually manage to reduce the mosquito population by 20 to 25% (as the Great Famine did in ireland) I'm sure you'll see an impact on the following years.

I honestly wouldn't expect that impact to last more than two years, if that. But that's a guess. (Consider again: in 50 years (roughly 2 human generations), Ireland's population grew 50%. If the mosquito generation length is one year, then at the same rate they could recover fully from losing 33% of their population in... two years. But insects generally follow a strategy of laying many, many more eggs than the environment can ever support as adults, so I'd kind of expect the effects to wash out in a single generation.)

[simias]

Maybe because mosquitoes don't have a culture? The trauma of the famine spreads across generations, it can have changed the mentality of the Irish people durably, made them have fewer children on average.

[thaumasiotes]

Well, I referred to that idea: http://en.wikipedia.org/wiki/Demographic_transition

But as something that happened everywhere[1], it's also hard to attribute to the famine. Then again, the only source I found (I didn't look hard) for Irish fertility data went back to 1975, so it might be hard to evaluate the theory.

[1] Demographic transition has not happened everywhere

[PeterisP]

It could have, but AFAIK we aren't seeing similar effects for other nations after having great famines with large mortality, so I'd assume that it's not the case.

[barrkel]

The effects of the Famine are still felt in Ireland today. It changed the way survivors thought, and altered the culture IMO. Though it's hard to say what Ireland would be like today without it having happened.

[smoyer]

African mosquitoes or European mosquitoes?

[coldtea]

>It's bizarre for a population bottleneck in 1852 to have lasting effects (on the size of the population) over 150 years after the cause of the bottleneck ended, much as I don't expect the number of mosquitoes in 2014 to go down no matter how many I manage to kill in 2013.

A bizarre claim. Unless you factor in your inability to kill that many mosquitoes.

Else, if you kill enough of them (or all), their 2014 number WILL go down.

After all, there are species made extinct, as well as lots of species that had their populations shrink significantly as a result of human action (sometimes temporary).

[thaumasiotes]

If you kill all the mosquitoes (at any stage of life) in 2013, their 2014 population will remain zero, yes.

If you kill less than that, then the 2014 population will be determined by the environment of 2014, mostly without reference to 2013. I pointed out below your comment that if mosquitoes could reproduce merely as fast as the Irish between 1961 and 2011 (and in reality they do it much faster; a female human can't have more than about 15 children, whereas a female mosquito can easily lay several hundred eggs), and their generation length were one year, then they would recover fully from a blow much larger than the potato famine two years after such a blow occurred.

Having looked into it, I see that the actual generation length of mosquitoes ranges from several days (!) to one month. So with very high confidence, I can say that the effects of a raging mosquito genocide will not be felt by one year after it has concluded, unless ALL the mosquitoes in the area were successfully killed.

You might find http://www.straightdope.com/columns/read/21/if-i-hadnt-kille... to be of interest.