I am sure that is it.
The earth became overpopulated when mankind was forced either to war or to farm.
Unfortunately, our own natures haven't completely adapted to an agricultural economy--leave alone to the industrial revolution.
People pay to vacation camping, hunting, fishing--people pay for the pleasure of experiencing hunting and gathering.
How many would pay to push a plow around a field all day?
Beer/Meed was the foundation of civilization.
Man was a hunter / gatherer of seeds.
One day he ate some seed that had gotten wet and had fermented.
He LIKED the buzzz / way he felt.
It took awhile for him to connect the dots from the buzzz to the fermentation process.
Then he said to himself, instead of chasing the crops, if I stay in ONE PLACE and plant this stuff I can have all the wet grain I need to get drunk on.
Hummm... D'oh!!!
Instant farmer / civilization.
How many would pay to push a plow around a field all day?
You've just created the latest Reality TV show!