Please let me know if I should be asking a different subreddit.
If the answer is that places where people are starving are poor, don't have access to birth control, have many kids as a social insurance policy - how is that different from the rest of human history?
Thanks!
You might want to cross-post this in AskSocialScience for another perspective.
First off, is your premise true?
Here's data comparing malnutrition rates with population growth rates. Without doing proper analysis there does appear to be a positive correlation between the two, but the effect size is not massive. It's hard to say if this is anything more than a correlation between poverty and growth rates.
Anyway, it's generally the case that there's an S curve in the relationship between population growth and incomes. What happens first is that mortality is reduced. This reduction comes primarily from better healthcare, disease control, sanitation, more secure food supplies. Note that many of these can be provided at a very low cost, or even virtually zero cost.
This leads to rapid population growth.
As an interlude, one feature of modern agriculture is that it may increase productivity while reducing food security. This can come through dependence on cash crops, monoculture or fertiliser. As Vandana Shiva has argued, the Green Revolution massively increased production, but turned agriculture from a relatively closed loop to one requiring constant inputs. If those inputs are disrupted - soil fertility falls, fertiliser becomes unaffordable, prices for cash crops crash... - the system can fail.
If development continues, once incomes reach a certain level, birth rates start to fall. This is due to things like lower infant mortality, a higher opportunity cost for having children (ie. the work you give up to look after them), more opportunities for skilled workers (making it worth investing more in fewer children), better social security and saving, better family planning capabilities.
So this is one reason why population growth may appear higher in countries with greater food security problems. They have entered the demographic growth phase, but incomes haven't risen enough to reduce birth rates. Other countries have increased incomes, providing better food supplies, and reduced birth rates. There may even be an equilibrium trap where the population rises too high for agriculture to develop the surpluses to fund growth. (It's plausible, but I don't recall seeing this argument.) Of course, these are all general trends, and there are countries that are outliers (eg. gender equality is a major factor influencing birth rates).
Another factor may be that famine is not necessarily related to insufficient food supplies. This has been famously argued by the economist Amartya Sen. So, for example, in the Ethiopian famine, the problem was not so much a lack of food in the region, it was problems of distribution and the areas suffering having money to buy food. Likewise, in the Irish potato famine, the United Kingdom still had high tariffs to keep out the increasing supplies of grain from the international market. So there was no shortage of food in the United Kingdom, but with their crops destroyed, Irish farmers didn't have money to buy food.
Because an improved food supply does not cause population booms. Actually, it is an important factor, but food supply on its own won't drive population growth and as you have observed, populations can grow when there isn't ample food available. The equation is more complex.
This is an oversimplification, but if you had to name a direct cause of population growth it would be fewer people dying (especially fewer infants and children). Having food is an important part of staying alive but there are other factors too, such as...
http://www.nber.org/papers/w20448
This is a recent paper on population booms after natural disasters. They postulate that families who lost members as a result of natural disasters responded by reproducing more than families who dI'd not lose members in the disaster. Their hypothesis is families produced more in order to ensure the survival of some members. The families who did not lose members in the disaster reduced their reproduction levels. The idea here is if I am going to lose family , I will make more in order to ensure the survival of my genes. However if I didn't lose any my response is be conservative and ensure the survival of the members I already have. This was covered in a freakinomics episode. While I dont neccasarily see this as historical , I do believe it can contribute to the discussion.