A paradigm applicable to “H. Sapiens”.

On the other hand, the great mass extinctions of species were in the main triggered by external forcing, including endogenic volcanic eruptions and extraterrestrial asteroid/comet impacts.

The latter resulted in some instances in the release of CO2 and methane from target rocks such as carbonates and carbonaceous shale , where they accumulated as a result of biogenic activity.

Otherwise the great mass extinction events were essentially due to external forcing unrelated to notions of self-destruction, which renders terms such as “Medea” or “Cronus” less than consistent with the origin of these events.

TerjeP #15, you are right that Dawkins focuses on the selfish gene rather than individual choices. The species in the Cronus model is, in many ways, more akin to a gene than an individual, because species don’t make ‘decisions’ (this would imply group selection, which is pretty well discredited).

The notion of a community of species as a population of selfish individuals retains the Darwinian view of contestation

In “The Selfish Gene” Richard Dawkins very convincingly makes the case that the pure Darwinian selfishness is an attribute of genes not individuals. And he puts it together with some very neat game theory and mathematics. In doing so he explains why individuals are frequently not selfish and the circumstances where altruism is most likely. I don’t think anybody should venture into this field without Richards book very high on their reading list.

I’ve heard it said that it takes about 2 million years for species diversity to fully recover after a major extinction event, presumably this is based on fossil evidence.

I’ve got no problem with Gaia theory in its strictly non-teleological form (it’s not the planet that does the optimising, the stable conditions are an emergent property of the system as a whole). Though like many, I really don’t like the name. You could argue that anybody who talks about an Earth ‘system’ is tacitly accepting the important idea in Lovelock’s thinking.

I don’t know much about Medea, but it seems to assume that all the major extinctions in Earth’s past were caused by life. I’d heard of the oxygen catastrophe (and the follow-on first snowball Earth event) being caused by the first photosynthesising microorganisms, but I’d understood that many (if not all) of the later extinctions had abiotic causes such as flood basalt eruptions/asteroid impacts etc. Is there any substantial evidence to suggest otherwise? If not, the Medea hypothesis rests on shaky foundations…

Of course there may be periods when unstable positive feedbacks develop, and Cronus is nice because it’s an overarching idea which links them to the stable periods, but in the case of the Earth these episodes clearly haven’t been overwhelming destructive and de-stabilising, or we wouldn’t be having this discussion now. Maybe these are the early coarse fluctuations which occur as a planetary biogeochemical system becomes established?

Perhaps we need to look at more planets to settle this. Roll on ESA’s Darwin mission!

We hope so, but the idea needs to be developed further to generate some useful hypotheses for testing. We wrote this when speculating about that:

“Analogous to Lovelock’s parable of Daisyworld for applying a mathematical framework to the Gaia hypothesis (Lenton & Lovelock 2000; Watson & Lovelock 1983), a Cronus view of evolutionary and extinction dynamics could be modelled by modifying existing metapopulation tools (Hanski 1998, 1999). For example, species as individuals with particular “mortality” (extinction) rates, and lineages with particular “birth”; (speciation) rates, could interact and disperse among “habitats’ (biogeographical realms). “Density” feedback could represent anything from competitive exclusion to parasitic, mutualistic or commensal symbiosis.

As a “population” (species) declines, perverse feedbacks such as inbreeding depression can induce Allee effects (Courchamp et al. 2008) that further exacerbate extinction risk – this is one Medean-like phase of the population analogy represented by Cronus. In contrast, stochastic fluctuation around a “carrying capacity‟ (niche saturation; energy limitation) achieved through compensatory population dynamics arising when environmental conditions are relatively stable becomes the Gaia-like equilibrium embedded with Cronus. The Cronus model also has the advantage of being scale-invariant – it could be applied to the turnover of microbial diversity inhabiting a single macro-organism through to inter-planetary exchange of life. When combined with more theoretical development (and, ideally, experimental or numerical testing) of the thermodynamic model of biological entropy, Cronus mathematics can be used by evolutionary ecologists, palaeontologists and exobiologists to pose and test novel hypotheses regarding the ever-changing patterns of life on Earth.”

The metapopulation model development of Cronus would be the next step — something Corey and I have been talking about how to do.

Victoria cannot unilaterally limit global emissions, the coal products could help developing countries overcome poverty, and emissions may be even higher if countries are denied Victorian coal and use dirtier fuels

Well that’s OK then not sure if they could find a dirtier fuel, old tyres maybe. T. rex never claimed to be helping its fellow dinosaurs. Humans are different to anything before in biological history; they can recognise signs that the commons are being overused but talk themselves out of evasive action.

As we speak the Lake Eyre pelicans could be providing an example of what’s in store http://www.efarming.com.au/News/agricultural/14/09/2009/70339/life-and-death-in-the-desert.html

I am sick of these self-loathing nothings who haven’t made a life for themselves waxing on about how Man should vanish and how perfect the world would be without us.

The meaningless of your existance is not a lien on the rest of us, like the old song says, we have a right to be here.

I think it’s time you got off the plok and went to bed. Things will look better in the morning. ;)

Our days are counted, let AGW be the Devil, no problem.

Unlike most species our intellect allows us to adapt to change much more rapidly and much more successfully than any of the other higher organisms. Furthermore, as the hair-shirt Greens are always telling us, there are populations that manage to thrive using very little energy or materials. Consequently while standards of living could plunge if we keep pretending that we can do without nuclear energy, it is unlikely that we will be threatened with extinction over lack of energy.

Histrionics and hyperbole aside, what the energy debate is about is what standard of living we wish to attain, not about the survival of the human race.

Linking this to the perennial topic of pumped hydro there is long cut in late Permian-early Triassic rocks where the high voltage cable extends from Gordon Dam to Hobart. That dam is 40% full despite 3 metres of rain and has vacant slots for 300 MW turbines. As you walk along this cutting you can see how marine life went though short lived revivals then became totally barren for tens of millions of years. Layers with fish put in an appearance, then later rocks elsewhere show reptiles, early mammals and so on. The point being that the dominant taxa in the revival were not descended from the dominant taxa before the extinction event. Perhaps Earth II will belong to the insects. Since there won’t be enough time to form more oil they won’t make the mistake of burning it.

http://www.abc.net.au/news/stories/2009/10/13/2712317.htm

The hearts, minds and pockets of the community need to be engaged in the debate.

It may come from left field but one thing that I have recently seen mentioned by other commentators is the “Homer Simpson” effect on much of the mind set of societies view of the Nuclear Industry.

I have watched with my children the Simpsons throughout their formative years where they and I dare say many adults were subtly programmed to focus through humour on a less favourable view of the nuclear industry. (I suspect it may well have had a greater influence than many anti nuke demonstrations on societies position in the late eighties and nineties and now).