Hey everyone, this is my first post here, and its some thoughts I had on this subject, and a hypothesis, I just wanted to post it to see what others might have to contribute to the discussion....
I posted a longer version on another science discussion website, but it was quite long, so I trimmed it a bit. - its still long!
Hypothesis
The health, robustness, adaptability, ability, and vitality of the population (macrobiological scale) of living organisms on the planet is in a decreasing trend.
Now, I know that the historical evidence of the fossil record contradicts this, but please get to the bottom of the post before you dismiss it
Definitions: I had wrote the definitions of health, robustness, adaptability, ability, and vitality, but I guess you can just look them up and figure out how to apply them
I dont know a the best way one would go about quantifying these things, but as I was looking into it, the concept of genetic diversity seems very important. It probably doesnt encompass every factor, but its importance for robustness and vitality of individual species is well documented.
http://en.wikipedia.org/wiki/Genetic_diversity
I looked at the different mechanisms of evolution, and classified many of them according to their impact on genetic diversity. These classifications are my assumptions according to how well I understand them, and those assumptions may well be wrong, and if so I would appreciate someone enlightening me. Also, I'm sure its an incomplete list, but these seem to be the major drivers as far as they are known so far. Additions to any group are welcome. The classifications are based on whether the mechanism BY ITSELF adds to genetic diversity of the original + new population, is neutral, or contributes to a loss of genetic diversity. I understand that these mechanisms are all working together at the same time, which is generally understood to lead to increased genetic diversity across the biological population.
Processes that increase genetic diversity:
mutation (there must be more, what else?)
Neutral processes:
genetic transfer between populations
genetic recombination
gene swapping (bacteria)
Processes that decrease genetic diversity :
genetic drift
natural selection
disruptive selection
stabilizing selection
directional selection
adaptive radiation
population bottlenecks
the founder effect
Perhaps the thoughts can be boiled down to this, it looks to me like the mechanisms that decrease diversity are greater in strength than those that increase diversity. It seems like, and I'm bet it could be calculated some how, that the rates of removal of diversity can be demonstrated to occur faster than the rate of increasing diversity. As for increasing diversity, The fossil record is only acceptable as circumstantial evidence in this case, as it seems to be showing a trend of increase in diversity, but its just a history book - and if we are reading it accurately, we should be able to observe and document the rates at which natural mechanisms are able to increase genetic diversity.
Why the hypothesis is needed: Its possible that mechanisms that tend to increase genetic diversity within a population are not sufficient to stabilize or overcome the known mechanisms that tend to decrease genetic diversity with in population. In order for the overall process of evolution to have brought us from simple organisms to the complexity represented today, the natural methods of increasing and sustaining genetic diversity must have been successful to this point, or to some point of peak macrobiological genetic diversity in the past. The historical evidence suggests this to be true. To validate that the processes identified to be at work today are sufficient to generate increased genetic diversity would validate the historical evidence. If it cant be demonstrated, its possible that 1) there are natural mechanisms that contribute to genetic diversity that have not yet been identified. 2) there were in the past processes that contributed to genetic diversity in the past that are not occurring now. (I cant think of any accepted historical evidence to support this) 3) The processes collectively known as evolution is insufficient to account for the macrobiological genetic diversity that currently exists (historical evidence contradicts this)