Page #44
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.
Q: So there is a history of dramatic reductions in the size of the population of our species?
MA: Of course, we are not above the biological forces that regulate all life.
Q: MA I have a bit of a faux pas to admit to you.
MA: And what would that be?
Q: 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. 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."
Q: Sexual Dysfunction?
MA: Well to put a finer edge on it - reproductive dysfunction.
We mammals have evolved a behavioral and physiological response to any population crisis. When a mammalian population becomes dangerously dense, there is a reversal of behavior. Co-operation is replaced by competition, dominance and aggression. If this sound familiar to you - it should. Also in these times of population stress you will find infanticide and gross neglect.
The resulting stress and violence also impairs both the immune and the reproductive systems. That is why epidemics often complete the crash of the population.
In some mammal species, crisis and crisis response recur regularly, leading to cycles of population growth and relapse, oscillating about a fixed mean. Here you can think almost any wildlife species - deer and coyotes are very much in the news now because of exactly these factors.
Q: Is it true for humans as well??
MA: Well, in man successive advances in food production have made possible geometrically growing populations, and unlike animals, we can choose to check population growth by reducing the birth-rate, instead of raising the death-rate, as in other mammals. However, even with a flood of abortions, China's single child policy, Europe's low birth rate and other measures we are still on a very sharp curve.
No we are very much in the same stew as our more furry friends.
