The Guardian runs , well, it’s more than an extract, more like an abstract, of Jared Diamond’s Collapse. I was thinking of doing a full on fisking but that is just so 2004. This one small quote
should be enough to eviscerate his entire thesis:

"The world’s food problems will be solved by more equitable distribution and genetically modified (GM) crops"

The
obvious flaw is that first world citizens show no interest in eating
less so that third world citizens could eat more. While first world
countries are willing occasionally to export food to mitigate
starvation occasioned by some crisis (such as a drought or war), their
citizens have shown no interest in paying on a regular basis to feed
billions of third world citizens.

If
that did happen but without effective overseas family planning
programs, which the US government currently opposes on principle, the
result would just mean an increase in population proportional to an
increase in available food.

Both Malthus and Garret Hardin were wrong. No, not in their analysis, either of them. In the thing they didn’t know. Both assumed, as was observably true, that an increase in food supply would lead to an increase in population. Both also assumed that there was no natural (other than disease or war) natural feedback which prevented this from always being true. We now know, a couple of centuries after the first and a few decades after the second’s seminal work (Tragedy of the Commons) that this formula does not hold true for humans. Wealth is that very feedback. As people get richer they have fewer children. There are a number of economic reasons for this, which I call Worstall’s postulates on population. (Partly because I am an egomaniac, partly because I actually thought one of them up myself and mostly because I haven’t gone deeply enough into the literature to find out if anyone else has laid them out in this manner.)

1) Increased wealth raises the opportunity costs of having children. Wealth brings choices, so having a child for a wealthy person is a denial of more of those choices. Pretty much a "No, duh?"sort of statement.

2) Urbanisation reduces the opportunity costs of not having children and raises the opportunity costs of having them. Four year olds are an asset in a peasant agricultural society, not so in an urban one, they are a cost. Urbanisation is associated with wealth…we are just getting to the point where 50% of humanity is, for the first time in history, urban.

3) Wealth reduces the opportunity costs of having fewer children. (Doesn’t matter whether your worldview is biblical, go forth and multiply, or Darwinian, the name of the game is to have grandchildren.) Wealth means higher survival rates of children, whose children themselves have higher survival rates. One therefore needs to have fewer children in order to ensure grandchildren. We can actually see this in the demographic records….the generation after most children survive, numbers of births fall dramatically. In western countries, many decades and generations before cheap and effective contraception.

4) Wealth, and its associated (we can argue another time whether wealth is caused by women’s empowerment or contributes to it) change in the balance of power between the sexes means that women are both more economically valuable and have more decision making power themselves. That’s the standard line anyway, that women have in some way been oppressed into having many children , something that only their empowerment by means of family planning services can liberate them from. Oddly, all the surveys done on desired family size appear not to show this. There is no huge gap, and never has been, between actual family size and desired ( the former is always smaller than the latter as there are always those infertile or less than perfectly so). The change has come from changes in the desired family size, not from the mechanical ability to limit pregnancy rates to that desired size. The answer, therefore, must lie in one of the above economic arguments.

Anyway, all of this shows that Diamond is talking through his hat on this most basic of issues and that we can therefore safely reject the rest of his thesis.