Saturday, December 12, 2009

Medea Hypothesis Part 7: Ward's Summation


This is the final post summarizing the Medea Hypothesis. Rather than doing my own summation of Ward’s Summation. I will quote the important points. It’s about a page and a half, so it will be quick. The previous posts are here, here, here, here, here, and here. The completed Medea Hypothesis Review Table of Contents is here.

Ward’s Own Summation
Let us sum up – in the shortest chapter of all. Three hypotheses have been presented. The first, the Gaia hypothesis (Optomizing), promotes the idea that life makes conditions better for itself. The second Gaia hypothesis (Self-regulating or Homeostatic) posits that life maintains conditions that, if not optimal, certainly stay within habitable bounds. Third, the Medea hypothesis suggests quite the opposite – that life, and future life, limits itself in any number of ways and does so in no small way by causing positive feedbacks in various ways necessary for life. A number of specific tests were supposed early on. They included the following.

1. Does the history of life support the Gaia hypothesis? It should show ever-increasing diversity through time. It does not Diversity of animals and higher plants seems to have been in a steady state for more than 300 million years since the evolutionary conquests of land, with this long-term value depleted on occasion by mass extinctions. Second, we do not know what the diversity of microbial life was prior to animals, but it was likely higher. The almost complete loss of stromatolites with the Cambrian Explosion indicates that microbial biomass was certainly higher prior to animals, and it may be that biodiversity was as well.

2. Does the history of biomass through time support the Gaia hypothesis? It does not. Model results indicate that biomass on Earth peaked some 1 billion to perhaps 300 million years ago and has been diminishing ever since. Since two main factors biomass values – temperature and atmospheric carbon values – we should look to these two. Temperature has remained faily constant, byt carbon values have plummeted as CO2 has been removed from the atmosphere by increasing carbonate silicate weathering by plants, as well as the increased efficiency of carbonate skeleton production by animals and plants, microbial to macro in size. Both of these factors causing reduction of CO2 where caused by life. This is not in accordance with predictions from either Gaia Hypothesis

3. Will the future of biomass show a steady decline through time up until the loss of the oceans? The Gaia hypotheses predict that life will extend the life of biosphere. But model results suggest quite the opposite – that, through the removal of CO2, life itself will cause a shortening of the timeframe within which the Earth can sustain surface life. While microbial life might still survive folliwng the loss of plants, an oxygen atmosphere, and finally the oceans, where is no consensus that the Deep Microbial Biosphere can withstand the loss of all surface life.

4. Do individual events during the life of the biosphere show evidence of Gaian influences? Since the main life-related events on the planet after life’s first appearance include the oxygen rise, the Snowball Earth events, the Cambrian Explosion (appearance of animals), and the various Phanerozoic mass extinctions, this question can be proposed in the light of these events. Each, however, produced a reduction of biomass at the time.

In summary, the four points above seem to me, at least, sufficient to falsify the Gaia hypotheses. Does this mean that the Medea hypothesis is correct? Not necessarily – the hoary “more research is needed” is all too true. But the evidence at hand certainly points to it being a better descriptor of how life works than the Gaia hypotheses.

Pages 126-7, Chapter 9: Summation, The Medea Hypothesis, by Dr Peter Ward.

A Postal Conclusion

Ward writes further in the book, but it deviates away from the scientific into the political and cultural. It goes on about the misconception that if we stop interfering in nature that life will heal everything. He goes on to say that it won't. I happen to sorta agree with him, but I am not here to examine the political aspects or modern ecological recovery. I'm here to examine his Medea Hypothesis.

The next post will be a critique, but it might be a while before I can write all of it. This is going to be long. Wow. Just getting to this point was long!

1 comment:

Anonymous said...

See Life's Principles at the AskNature website. Very similar. Cheers!