J: That makes very good sense to me MA.
J: So when you speak of being worried about challenges to our continued population growth (as a species) you are using that predictability?
MA: Very much so James. While we may be the overwhelmingly dominate species on this rock, it would be sheer vanity to believe that we exist out of the normal natural processes of life. It just is not true.
Our species is subject to all the forces that influence, regulate and contain population growth - we are not Gods. However it is our ability to understand and react to those forces that is our strong suit.
J: What kind of forces are you talking about?
MA: Well the most basic dynamic is simply this:
Is the birth rate larger than the death rate? If the answer is yes then you are in an era where the species is expanding.
J: Haven't we always expanded as a species?
MA: No, not at all. We have had a number of events that we call bottlenecks. A population bottleneck is where a significant percentage of any species is either killed or prevented from reproducing.
There have been a number of these events in our history, but the time-line, severity and number of bottlenecks is a very hotly debated subject. It depends a lot on which gene you backtrack.
But there is a general consensus that we might have been reduced to perhaps only 5,000 reproducing females around 70,000 years ago.
That is a very large event and the genetic implications of such a bottleneck are equally significant.
...
MA: Of course James, we are not above the biological forces that regulate all life.
J: MA I have a bit of a faux pas to admit to you.
MA: And what would that be?
J; In my first article, where I was trying to summarize your views on this subject, I used the term “the thinning of the herd” - and was severely castigated on several of the sites that were posting my thread. It almost crashed my project.
MA: It is a very loaded expression James. Many very ugly ideologies are associated with this phrase. It implies human intervention and some sort of selection process - like in animal husbandry. Bottlenecks in species are not like that at all. Often it is just a function of geography or climate.
There are, of course, dominate trends in these occurrences. I had a brilliant colleague who put it this way: "Among the classical markers of a species in crisis are sexual dysfunction and disease." Now there are occasions where this is not the case but it is true in the large part.