The Coming Wave Page #53
MA: Yes of course, it is once again the collision between two different evolutionary currents. Immigration from other countries is sparking a baby boom in some areas while the resident population is declining as a whole. It is an uneven picture. One wave is reproducing and spreading while the other current is falling further and further behind even meeting the fertility rate necessary to maintain their population.
That is what we mean when we speak of differentiation between members of a species. Differentiation in reproductive strategies to the same environment is a pretty telling marker of evolutionary conflict.
Q: I believe that I have a good handle on this subject now; can I summarize what I have heard?
MA: Of course, go ahead.
Q: This discussion originated when we speculated on the future of our species in a changing environment. You have since tried to teach me some of the dynamics involved in making such a prediction.
What I now understand is that from the beginning our species has been subject to at least two different evolutionary strategies involving reproduction, fertility rate and species expansion. Good so far?
MA: Excellent, and especially the part where you say “at least two”, because there are many factors involved - but these two paradigms are easiest to understand. Please go on.
Q: Our current large population numbers are the results of countless surges, crashes and plateaus of population growth. During this long evolutionary development, some varieties of humans have risen to prominence then completely disappeared due to competition from a better adapted group.
MA: There is nothing wrong with the word variety but you might be better served to use the term groups.
Q: Point taken. These surges in population growth by one or more groups are described, by you, as waves.
Q: There have been large waves like the one out of Africa, the one across the Bering Strait and the expansion of the Old World into the new. But there have been lots of smaller waves within those events - like Clovis Man and others. The current wave started after the Black Death and the migration to the New World. That wave (which you and I have been calling the First Wave) rolled across the planet and finally peaked in the early 60’s.
From that time on the rate of increase in the total number of humans has been slowing. However, there are cross currents within that decrease in rate - as there are with many other species. I also understand that there are very distinguishable traits associated with what is called an “r-selected” species, such as early maturity, a large number of offspring, limited or no parental long term investment in these offspring, and that this behavior normally leads to a rapid expansion of that species and a sudden collapse in their numbers.
There are also distinguishable traits associated with what is called a “k-selected” species, such as late maturation, few offspring and a large investiture in those offspring, and that this behavior typically leads this group to fully occupy the habitat, at that point their numbers level off and arrive at some type of balance with their environment.
MA: That is pretty close.
There is one caveat that I should add. In old school Biology we would normally think of any single species as either K or R selected. The understanding that there are multiple expressions of both these traits within any given species, while not controversial, is new. Not a large point but one that could be questioned.
Q: I understand that, although it is difficult to see how you could not see the different strategies in our species.