War and Obesity: the human condition

In many places in the world, food is not abundant, and many people starve. But in the US, most people can afford to buy more food than they could ever possibly eat. Some of us can just eat and eat like slobs and never gain a pound (don't cry for me America), while others become overweight. However, bacteria don't get obese, they just make tons of children. In the long term even humans will follow suit, multiplying in the presence of excess food. As Darwin explains, a given population of organisms will grow exponentially until they use all available food. There is no doubt that the human population is growing at least exponentially (and maybe even superexponentially). Even if our current rate of food production were sustainable (which, because it's supported by fertilizers made from fossil fuels, some argue that it's not), we would eventually multiply to fill that vacuum. Until then, we will be overweight.

And once the number of people roughly equals the sustainable food supply, we will start to compete for those resources. We will go to war! Unless we can either a) transcend the laws of biology or b) find an infinite supply of resources, it seems that the human condition is to be at war. Let's examine two possible strategies to resist our fate:

1) The universe is infinite, right? Can't we just colonize every planet? This doesn't work for two reasons. First, while the amount of space is infinite, the amount of energy and mass (i. e. resources) is not. It's a huge amount, but given enough time we could expand to consume it all. Second, that still won't help the problem of local fluctuations in food, resulting in local warfare. Once we colonize the whole solar system, there might be a surplus of food on Jupiter, but we can't bring it to Venus, where people are starving. We have the same problem right now, on Earth, where one country gets fat while another starves and fights.

2) Our brains separate us from the animals, right? Can't we just all agree to have exactly two children per couple, plus a few extra in case of accidental deaths? Well wouldn't it be wonderful if we could all agree, but we won't. Those of us who do agree will pass on our agree-to-limit-procreation genes to a smaller and smaller fraction of the population than those with procreate-as-much-as-you-can-and-don't-listen-to-ecologists-or-bloggers genes. It's exactly the sort of trait that natural selection keeps a collection of on the walls of its hunting lodge.