Egos aside, these are the three key factors that were populating the Earth like rabbits on aphrodisiacs:

1) Food, basically no food/water then your dead simple as that. The more food the higher the population will grow, but once there isn't enough food it'll drop. When you KEEP ADDING more food then the population will continually go up and up. Thats what were doing.

2) Disease, big daddy Nurgle loves us all but so far we ain't returnin' the lovin'. Our increase in advanced medicine has quelled disease and sickness which would otherwise wipe out highly dense and populated areas, leaving food for the remainders not to mention that the life spans of our species has exponentionally increased from 20's-40's to 50's-90's. Disease and sickness kept our life spans relatively low thus we'd be dead by the next generation after our children but now were living through like 3-4 generations before we kick the bucket. Coupled with increased populations and food your asking for mother nature to bite you in the ass.

3) Our egos, and inability to pull our heads out of our assess and see that we are not so great has pretty much stopped any nature approved atempt at handling this situation, and almost completely ignoring that more people equals more problems. Especially since we live so long compared to back then.

This is assuming that the world doesn't become completely overpopulated in the next 100 years. I've read that they will be sending the first team of people to Mars in about 2030, but it's likely to be years and years before they are sending families to live there

Oh man, what?

Even if somehow NASA (or any space agency) built MASSIVE arcologies on Mars the likes we had never seen before they'd still only be able to house a few thousand people at most. It takes hundreds of years to (theoretically) terraform a planet and would take more fuel than the Earth has by several hundred times to move the countless tonnes of material required to build anything and the people to build it/operate the giant robots I assume we'd have building it.

Mars offers no answers for the "population crisis" on this planet.

The problem with all these people running around on Earth isn't necessarily that there is literally no room for us (because there is lots and lots left), it is that with every billion extra people the world produces we come that much closer to seeing nuclear powers involved in a war against each other. It also becomes harder and harder for the world to absorb our massive ecological impact, which it is already failing to do completely. Sure, we can almost always produce more food and design new living arrangements to house the people, but if people are worried about global warming with 3 billion cars (or whatever) tooting around, imagine what it's going to be like with 10 billion cars in a few decades. Even if we in North America and our friendly global neighbours in Europe start using alternative fuel sources like WATER or AIR or SORCERY or whatever wild plans are in motion, I seriously doubt the 1.1 billion people in India and the 1.7 billion in China are going to have any say in whether or not their use fossil fuels as their primary source (at least for a couple of years before we run out!). Now, of course, the strategic oil reserve pretty much guarantees that the USA is going to remain the primary economic powerhouse once that happens, but that doesn't mean it's good for the environment (does it ever?!).

So pretty much the problem isn't the population, it's what it's doing (eating the planet and pooping straight into the air we breath). More people just makes the problem worse, but even if we capped the population RIGHT NOW we'd still have lots of things to deal with.

Also 2 parents+3 babies=population growth. And lots and lots of people are having three babies pretty much everywhere it doesn't snow 5 months of the year.

We have the technology to stabalize our population, all we have to do is stop making more food and then our population will no longer increase and then will stabilize itself around that constant food source and also make having more then two babies illegal and punishable by the law. Thats all it takes.

Who knows maybe some day some idiot will find a way to utilize those bacterium in Termite stomachs into ours so that we can then eat wood. That would still increase the population because now theres tons of food and also have unforseen side effects.

It's not even worth worrying about. Even if we did overpopulate ourselves, the catastrophe that would ensue would bring us back to tolerable levels. Besides, nothing like that is gonna happen in my lifetime.

So the moral of this story is -- literally and figuratively:

"Fuckem."