What is Medean Life?

I am going to post the points testable points that Ward puts out there as what makes life, by definition, Medean instead of Gaian. I will quote what Ward says as the actual hypothesis and then summarize what follows in his explanation. First, however, let's examine what Ward is arguing against: Gaian life. According to Ward there are 4 main variants on the Gaia Hypothesis:

1. Optimizing Gaia: This is where life is constantly improving the conditions which it finds itself. "It implies that there is actual control of environmental conditions, such as temperature, oceanic pH, and even atmospheric gas composition...Another way of interpreting this hypothesis is that the biomass alters conditions on Earth to increase the 'hospitality' of the planet." Life is the optimizer in this variant.

2. Self-regulating Gaia: This where feedback loops in the environment that life is involved in are negative feedbacks, allowing life to not necessarily control conditions, but adjust them. Ward states that the self-regulating variant of the theory "supposes that the feedback systems allow the continuation of life on Earth by keeping life-constraining factors such as temperature, and even recently even atmospheric oxygen and carbon levels ... within ranges that allow life." Life is the stabilizer in this variant.

3. Coevolutionary Gaia: "[I]t simply advocates that the biota and environment have evolved in a coupled way." This is the 'weakest' Gaia hypothesis Ward states and that is essentially considered true at this point. Life effects the environment and the environment effects life.

4. Progressive, Deterministic Gaia: "Once life evolved, there came into existence a few possible pathways for how life and its systems would evolve further...simply a small number of nutrient and element cycles that affected later life." Pretty much self explanatory.

Now, in contrast what does Ward predict for his Medea Hypothesis. What makes life Medean?

1. "All species increase in population not only to the carrying capacity as defined by some or a number of limiting factors, but to levels beyond that capacity, thus causing a death rate higher than would otherwise have been dictated by limiting resources."
2. "Life is self-poisoning in closed systems."
3. "In ecosystems with more than a single species there will be competition for resources, ultimately leading to extinction or emigration of some of the original species."
4. "Life produces a variety of feedbacks in Earth systems. The majority are positive, however."
5. "Diversity and biomass can be independent and decoupled."
6. "The history of biomass (not diversity!) should show a series of steps - from the first formation of life harnessing ever more energy through better metabolisms. After some period of time, however, each group of organisms that utilizes the new kind of [metabolism] will show a slow decay, to biomass levels lower than those following the initial diversification of organisms."
7. "In all but regions of low environmental disturbance, ecosystems will eventually move toward lower species diversity as the competitive forms drive others species in extinction and as some species move into dominance."

pgs 29-37. The Medea Hypothesis. Dr Peter Ward.

In a quick summary, Ward holds that "life as an aggregate is negative to itself:" in essence, life, as a whole is suicidal and will shorten its existence faster than if it was not. It will use all of its resources up before any other influence - barring a freak occurance like a near by supernova - can do so.

Here's the start point of discussing Ward's extrapolations. First comments? Shots?

[btw, Carlos, he references Diamond. A lot.]

The Medea Hypothesis Review TOC is here.