The Coming Wave Page #50
Q: You said only two outcomes, what are they?
MA: Well in the “R-selected” species their populations explode, filling all the ecological niches they can endure and then they suddenly collapse with the glide ratio of a rock.
The “K-selected species” also explodes while food and habitat are abundant, and then they slow down as regulatory factors such as lower birth rate and reduced food availability come into play. The rate of population growth slows down to zero, and the population reaches a fairly stable level.
Q: Are we leveling off?
MA: Yes and no. No - we are still increasing the human population on earth but yes we are now slowing that rate of increase.
Q: When did it start slowing down?
MA: Somewhere in the early 60’s we reached our peak of a 2.2% increase and then we began to moderate that rate of growth. We now have about a 1.14% rate of growth which translates to doubling in 61 years.
Q: Has it been continually slowing?
MA: Yes, for the last 40 years.
Q: So if I understand correctly, we are modulating our population as we reach the limits of the environment.
That sounds like good news, is it?
MA: Well, let’s take a look at a very simple equation that will help us decide the answer to that question.
r = n - m
This simple equation means that the realized intrinsic rate of growth is measured by the difference between natality (birth rate) and mortality (death rate).
And obviously zero population growth is reached when r = 0, natality equals mortality, and the population size remains constant, even though individuals are being born and are dying.
It seems simple. To follow the perfect example of a perfect “k-selected” species - we would simply expand to the limits of our environment or as we often say –“the habitat's carrying capacity” - we would then modulate our birth rate to equal our death rate and live in the land of milk and honey.
But it is, as are many things in complicated systems, not that easy. We now understand that there are both “k-selected” and “r-selected” traits in many populations. Our species is riddled with such contradictions.
Let's start with a simple concept like rate of population growth. While it is true that the overall human rate of increase is modulating - that is not true for all components of that set. Most European countries have low growth rates. In the United Kingdom, the rate is 0.2%, in Germany it is 0.0%, and in France, 0.4%. Germany's zero rate of growth includes a natural increase of -0.2%, without immigration, Germany would be shrinking, like the Czech Republic