Quite rarely actually, politics remain the main cause of famine. Overpopulation can cause famine, but on rather localised areas (and even then, it's often politics which prevents food to reach these areas).
If there weren't too many people for that section of land, there would be food for them to eat. If the food needs to be brought in from other areas... it's ultimately overpopulation (of that area) that drives the famine.
Overpopulation creates unbalance in the environment, with lots of different consequences, like landslides such has happened in over populated Mount Elgon, Uganda, few weeks ago. A lush & fertile enough area to feed everyone living there, but so many people cleared the volcano slopes for growing, that nothing holds the soil anymore, and when rain comes it get disastrous.
If it were lush and fertile enough to feed everyone living there then there would be no reason for people to have cleared the volcano slopes for cultivation... which caused the soil to erode and rain to cause disaster.
Overpopulation of that area necessitated (in the minds of those doing it) the cultivation of those slopes.
Why in Kenya, in some places lions enter villages & houses at night to catch someone for diner. Overpopulation has caused encroachment on the lions territories, with disastrous results, but no famine.
I didn't say that overpopulation always instantly leads to famine.
There's famine in some North-Western Nepal valleys (a very very well hidden famine), but not because of overpopulation, it's because rain doesn't fall enough anymore overthere, and crops don't grow.
Because they were already overpopulated enough to need to cultivate crops (in order to feed this population), when the rain failed, the crops failed and there was not enough food to support the people in the region. Therefore famine caused by.... ?
Nepal Gov; could shuffle food there, with some copters, but seems it doesn't happen. Is there a political reason or will, not to do so ? probably. As a matter of fact, only a French NGO is bringing food to these people, not with copters, but with porters.
This is an example of the transportation system breaking down, leaving the indigenous population without the natural resources to hunt and gather their own food. There are too many people living there, so they have to depend on crops. When crops fail, they have to depend on transportation of crops. When transportation fails they are faced with famine based on overpopulation of a given area.
If in the past, overpopulation might have created famine, it is something totally impossible in today's world. There are enough stocks & money on the planet to kill any famine in the egg. BUT, is there the political will to do so ? certainly not.
A grain of truth in there. But still, overpopulation of a given area (beyond what that area can naturally support) is the root cause of these famines.
few years ago, Malawi experienced some famine (not enough rain, bad crops). The UN World Food Program called for help from wolrd governments, nearly no one gave.
Too many people for the area to support, so they turned to agriculture.... when agriculture failed (not enough rain, bad crops) there was a famine caused by too many people living in a region which could not support their food needs. (Then there was a transportation break down and they couldn't get supplies from elsewhere.)
Same happen regularly for Afghanistan during winter time. WFP calls for help, nearly no one gives. Governements don't give a shit about famine, this is a fact. In today's world, the only cause of famine is politics, period.
The main cause of famine is the overpopulation of the earth which is CAUSED IN THE FIRST PLACE by dependence on totalitarian agriculture!
A small tribe living in the middle of nowhere in the Australian outback does not need to grow copious amounts of food in order to feed their population. They find it growing on the side of the river, crawling across the dirt path, swimming through the streams, flying through the trees.
Once that tribe begins to practice agriculture as their primary means of sustenance, any excess food produced will be used to create new people, which will put a strain on the food supply, which will in turn require more land to be put under cultivation, which will in turn lead to new people, which leads to more land under cultivation....which leads to expansionism, which leads to poverty, classes, war, etc.