In our ecology sometimes things get out of balance. Subtle things that you wouldn't notice might make a huge difference.

The populations of various types of species, most noticeably insects, can suddenly spike to many times its annual average.

Things as subtle as a five degree variation in temperature, an inch or two of rain one way or another or even a early or late frost can cause huge variations in different types of species.

These events are called population outbreaks and can happen in certain types of species with regularity. Not just with insects but micro-organisms and even higher marine and terrestrial animals.

The key question is why but often the answer is quite elusive. Outbreaks can occur in diverse populations: algae, gypsy moths, forest tent moths, Japanese beetles or starfish. Sometimes they tick along regularly like 7 year locusts or exceptionally haphazardly like red tides.

One of the theories behind why this happens is called catastrophe theory. It has nothing to do with disaster or apocalypse. Catastrophe means the loss of stability in a dynamic system. The major method of this theory is sorting dynamic variables into slow and fast. Then stability features of fast variables may change slowly due to dynamics of slow variables. Now we enter the realm of differential equations and things get murky so lets look at a simple example.

Every few years in the American South we experience a very mild winter. Typically, southern winters have 5-6 frost events with temperatures in the twenties or below. Every few years we have little or no frost.

This changes the dynamics of the ecological system significantly. Plants that grow as annuals don't die. Insects that are typically killed off en mass when temperatures go into the twenties survive and even thrive. So what happens when the mosquito population isn't wiped away by winter?

What happens is that they do actually die but their reproductive cycle is doubled and the following summer the population spikes at three to six times normal numbers. This causes a great deal of misery. The hungry little bastards do their best to make life miserable and worse- spread mosquito born disease. While Yellow fever is a bad memory in the American South, West Nile has arrived with a vengeance and Dengue may not be far behind.

The ecology is a massive and complex system that we are only beginning to understand. There are so many dependent and independent variables that what we call science is really a matter of a string of educated guesses. The more that we learn, we simply comprehend the true depth of the complexity. Small changes can yield exceptionally large results.

We like to think of ourselves as above the natural world but we are an inextricable part of it. We are bound to it by our very DNA. We have a great deal to learn and as we see minute changes that may be the beginnings of climate change, the stakes of understanding our ecology are raised to exceptional levels.

There is a second and inevitable part to population outbreaks. Once that population is outside its stable dynamic, there will always be a population crash. The system will return to equilibrium.

This is something that a population that recently passed 7 billion should consider carefully.

It took from the depths of antiquity to some time in the 1800s to reach a population of 1 billion. Then it took another 100 years to double it. Since that time, human population has surged 350% with no end in sight. One might argue that humanity is in a state of population outbreak. As with all population outbreaks, something is going to have to give for our population to reach a stable and sustainable level. The system will return to equilibrium.