Overpopulation or lack thereof: Your thoughts please?

Overpopulation was mentioned in another blog here - and this is something that I'm always interested in discussing, so I wanted to see what other mamas opinions here were.

I did my undergraduate degree in physics, with a focus on environmental physics. My teachers taught there there is definitely a population crisis happening - but this was physics, and not sociology, so I was taught this through equations that dealt with land and water resources, caloric requirements for human beings, etc... and we did not talk about solutions to this problem, nor the sociological impacts of this problem.

Last week in another thread here, I saw it mentioned by a couple of mamas that they've heard that the population crisis is unwarranted...and I'd like to read and talk about the arguments for that, because I hadn't heard them before. Rather, I've heard arguments about whether or not we have reached the Earth's maximum carrying capacity YET.

Garrett Hardin wrote "The Tragedy of the Commons," in 1968. Since then, there have been various spin off articles that try and clarify, and put in simpler terms, what he had written.
(For an explanation of what the Tragedy of the Commons is, see Hanson's Tragedy of the Commons Re-stated.

His basic ideas were:
The human population grows exponentially.
This world and it's resources are finite.
Organisms require energy to live, and the more organisms, the more energy required.

Therefore...if the human population is not controlled in some manner, it will outgrow the resource potential of the earth. (This says nothing for the loss of other species life, but only for our own).

He also stated that the ideal human population is not equal to the maximum human population. (Meaning: just because the world CAN fit a certain number of people doesn't mean that we should aim for that, because an ideal human existence, in which we do not have to be rationed a daily caloric intake, etc... would mean that there are for more resources available than humans (or other animals) that need them.)

The big questions then become:
What is the maximum human population?
What is the ideal/optimal human population?
How do we keep population growth = to zero once we reach the ideal/optimal population?

Harding said, "We can make little progress in working toward optimum population size until we explicitly exorcise the spirit of Adam Smith in the field of practical demography. In economic affairs, The Wealth of Nations (1776) popularized the "invisible hand," the idea that an individual who "intends only his own gain," is, as it were, "led by an invisible hand to promote…the public interest." [5] Adam Smith did not assert that this was invariably true, and perhaps neither did any of his followers. But he contributed to a dominant tendency of thought that has ever since interfered with positive action based on rational analysis, namely, the tendency to assume that decisions reached individually will, in fact, be the best decisions for an entire society. If this assumption is correct it justifies the continuance of our present policy of laissez faire in reproduction. If it is correct we can assume that men will control their individual fecundity so as to produce the optimum population. If the assumption is not correct, we need to reexamine our individual freedoms to see which ones are defensible."

Which all comes down to the idea that, regardless of whether the population maximum has been met, it WILL be met, based on the previously stated ideas about population growth being exponential and resources being limited. This is where it gets really sticky, because as I saw in the previous blog, lots of us are saying that the government needs to keep their hands off our reproductive organs.

So, in terms of the Tragedy of the Commons and the individual putting their own needs and interests before those of the group, how does this play out? When Harding says that we can't be expected to control the population with our own consciences (because then those with no conscience will destroy the commons while those with conscience will die off), what do you think about that?

The other thing that I find interesting in the overpopulation discussion is that of the "carrying capacity" and "overshooting the carrying capacity."

The carrying capacity is defined as the amount of human beings that the earth can sustain. This is not the ideal population, but rather the maximum population -- meaning the amount of human beings that the Earth can feed, though what we are going to have to eat isn't going to be very tasty, and we will all be on a rationed caloric intake.
We may have already met the carrying capacity of the Earth (this is where part of the argument comes in), because Americans and other Westerners are consuming so many of the earth's resources while those in other countries are dying of starvation that if we were to mathematically subtract the excess from those countries and feed it to the starving nations, we may come up even.

The overshoot is defined as, ""Overshoot is the inevitable and irreversible consequence of continued drawdown, when the use of resources in an ecosystem exceeds its carrying capacity and there is no way to recover or replace what was lost. It takes many forms, depending on the system, but perhaps the clearest and in some ways the most touching is exemplified by Easter Island. When it was first settled a thousand years ago, the island was a rich and forested land covered with palms and a small native tree called the sophora, and on its sixty-four square miles a prosperous and literate culture developed organizational and engineering skills that enabled it to erect the famous massive stone statues all along the coastline. For reasons lost in time, the population of the island over the years increased to something like 4,000 people, apparently necessitating a steady drawdown of vegetation that eventually deforested the entire island and exhausted its fertile soils. Somewhere along the line came overshoot, unstoppable and final, and then presumably conflict over scarce food acreage, and ultimately warfare and chaos. By the time of Captain Cook's voyage to the island in the 1775 there were barely 630 people left, eking out a marginal existence; a hundred years later, only 155 islanders remained."

and overshoot results in a crash, which is a significant loss of life in the overshooting population. Many scientists believe that we are in an overshoot right now, which can feel like a time of prosperity, where everyone has enough food, but is then followed by a great loss of life through starvation and inadequate access to necessary resources.

So -- this is pretty incredible stuff for me to think about, especially as a parent. What are your thoughts?

I guess that part of me also thinks about why human beings are here (I believe in the whole Earth-as-an-organism theory), if there can be a "why." I have heard the idea that human beings are guardians of the Earth, acting as a sort of liason between the heavens and the earth...the ancient Chinese believed that we are made of earth and filled with heaven, and that puts us in a role of guardianship.
That gives me a lot to think about... in the terms that we do have a role to play here on the planet, and that part of that role is the governance of our use of the planet.

There are many other theories about why we are here. I think that the cultural myths that Daniel Quinn talks about in his book Ishmael (that modern day humans believe that they are the destroyers of the earth) really cause us to feel like nothing can be done about this, and it is our destiny to cause destruction, but I don't think I can buy into that.