Complex Ecological Asemblages Are More Productive Than Monocultures

Experimental evidence that evolutionarily diverse assemblages result in higher productivity

Author:

1. Marc W. Cadotte (a)

Affiliation:

a. Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada M1C 1A4; and Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3B2

Abstract:

There now is ample experimental evidence that speciose assemblages are more productive and provide a greater amount of ecosystem services than depauperate ones. However, these experiments often conclude that there is a higher probability of including complementary species combinations in assemblages with more species and lack a priori prediction about which species combinations maximize function. Here, I report the results of an experiment manipulating the evolutionary relatedness of constituent plant species across a richness gradient. I show that assemblages with distantly related species contributed most to the higher biomass production in multispecies assemblages, through species complementarity. Species produced more biomass than predicted from their monocultures when they were in plots with distantly related species and produced the amount of biomass predicted from monoculture when sown with close relatives. This finding suggests that in the absence of any other information, combining distantly related species in restored or managed landscapes may serve to maximize biomass production and carbon sequestration, thus merging calls to conserve evolutionary history and maximize ecosystem function.

And the Medea Hypothesis takes another hit and starting smoking on another front.  

Medea Hypothesis Review Conclusion

I am wrapping up my commentary on Ward’s Medea Hypothesis. This has been an extra long and ridiculous process. When I first started out writing about the Ward’s book, I never imagined that my commentary would still be unfinished nine months later. Here and now, I wrap this up though. While this final chapter is not going to be very long, unfortunately, this is not going to be a happy ending for any Ward supporters: this will be a bit harsh.

Ward can write. His prose is entertaining and he keeps his reader engaged. He can also write convincingly. So long as you do not look too closely. If you happen to have more than a cursory knowledge on a subject you get a lot of moments that are “huh?” and cause some head scratching. I can only imagine for the specialist in the areas that he is writing about that it would cause frothing at the mouth.

Sloppy, sloppy, sloppy

Ward’s work in the Medea Hypothesis is horribly sloppy. This may or may not be true for his other works, but it is painfully apparent in this book. Fact checking is almost nonexistent here. Conjectures are passed as fact. Criticisms were obviously taken, but only sloppily added in. The editing in general is atrocious. Works that were mentioned and cited are missing from the bibliography. A number of graphs and other bits are not provide a source. Those are just problems with the book on publisher/writer level. There are deeper levels of sloppiness here.

The basic thought process behind the hypothesis is horribly as well. This is something that I would have expected from a bright but not terribly well schooled undergrad. That is someone I would be expecting would be looking at the general works and not intimate with the details at all. It’s an old Friday Night Fight argument from my Las Cruces days. The equivalent of a beer and pretzels argument between friends, not something that ought to have presented by a respected paleontologist in the public arena.

Through the examples that I mentioned in the past posts on the Medea Hypothesis, you can see where the leap from A to B to get C just didn’t happen. A was often contradictory to B and C wasn’t even in the same parsec, nevermind with the proverbial intellectual wormhole between when you look at the accurate data. Ward makes leaps and unfounded bounds between inaccuracy and misrepresentation to back his idea. This is criminally sloppy.

Is there an explanation?

Ward’s rigorous work in the past is rightly acknowledged. He has done some things that have been immensely useful in establishing the KT Extinction as being catastrophic. He has made useful contributions to the work on the PT Extinction. If his published works are so useful, why is this popular work so awful? There is a reason, but its even more awful.

I think Ward’s words speak for themselves:

This could be the end of the book. But it was never my goal just to lay siege to the Gaia, replacing the benevolent mother figure with a silent murderess. Let us move to two final chapters: the first dealing with environmental implications, and the second, a brief essay on what we might do to save our species from extinction.

The Medea Hypothesis, Pg 127.

If you view the Medea Hypothesis through the lens that the Medea Hypothesis was purely an agenda driven piece of “science,” then everything falls into place. Ward assumed his conclusion and forced, shoehorned and bent evidence so that he could show he was right. This isn’t science. This is something else.

Ward didn’t come to his idea because the evidence compelled him. There was no intuitive leap. It was that Ward wanted to knock the “Deep Greens” on the head for their silly beliefs. Don’t get me wrong: the Deep Greens frequently make me see red. However, pursuing truth by perpetuating falsehood is not the way to do it.

Summation (Duck Roast Time!)

Ward presents an interesting idea: that the Gaia Hypothesis is wrong and that there is an alternate one we ought to consider. Unfortunately, in his writing and presentation, Ward commits numerous egregious sins. Perhaps there is something to the Medea Hypothesis. Perhaps there is a kernel of truth to his idea. However, given that it seems to say that life systems are subject to entropy, too, it feels like we have been put over. What did he really prove? That the Gaia Hypothesis was wrong? Not really. In his effort to present an alternative, the book largely fails.

Ward did highlight some things that are more than worthy of our attention and have not been brought into the public eye much. The first is that there are numerous positive feedback cycles in the biosphere that need to be watched. They need to be brought out into the open as things we need to be concerned about and they are far more nuanced than comments on the tipping points in global climate change. The second is that, yes, biogenic climate change does, in fact, happen. Life changes the atmosphere enough that it will cause the climate to change. That, too, is something that needed to be exposed to the public light since by and large it has not right now. It’s a real pity that he decided to stitch these into an agenda driven ‘grand narrative’ he did rather than write about the feedbacks and biogenic climate change. He would have had a riveting book there and then on largely unknown subjects.

Instead, he overreached, warping the presentation around his agenda, and has muddied the waters. The discussions will no longer be on the merits of the science, but rather the back and forth that takes place over him and his flawed, inadequate and very agenda driven interpretation of the science. The idea of the Medea Hypothesis may, in fact, be worth considering. However, because the book needed a few more iterations through rewrites and fact checking, his idea falls flat and probably will not be considered in a rigorous manner.

Perhaps he doesn’t care. Perhaps he’s merely trolling the environmentalists, the Deep Greens, that he seems to despise while winking at the rest of us; however, perhaps I’ve lost my sense of humor, but I detect no wink. I do think he ought to have taken a little more effort, a little more care in his work rather than extruding book after book. Maybe I am wrong and simply am nitpicking. However, I don’t believe so. I have to say that I think Ward let his agenda hijack his work and because of it, now all his popular work, at least, must be subject to a very, very careful scrutiny for bias…and factuality.

I doubt that this review will have much impact on people’s purchase or view of Ward’s works. There have been numerous sources of strong commentary on Jared Diamond and his extraordinarily dodgy works. However, Diamond’s still venerated even by scientists, sadly enough. Ward isn’t Diamond. However, this latest work suggests a future of Diamondism. I sincerely hope I am wrong about that though.

That's it. I'm done. Thank the maker. This could use an edit or two, but I've had enough of Ward's idea. For all the posts, go to the Medea Hypothesis TOC.

James, there ya go. Link away.

Faint Sun Paradox Solved?

Researcher unravels one of science's great mysteries

Climate scientists from all over the globe are now able to test their climate models under extreme conditions thanks to Professor Minik Rosing, University of Copenhagen

In 1972, the late, world famous astronomer Carl Sagan and his colleague George Mullen formulated "The faint early sun paradox. " The paradox consisted in that the earth's climate has been fairly constant during almost four of the four and a half billion years that the planet has been in existence, and this despite the fact that radiation from the sun has increased by 25-30 percent.

The paradoxical question that arose for scientists in this connection was why the earth's surface at its fragile beginning was not covered by ice, seeing that the sun's rays were much fainter than they are today. Science found one probable answer in 1993, which was proffered by the American atmospheric scientist, Jim Kasting. He performed theoretical calculations that showed that 30% of the earth's atmosphere four billion years ago consisted of CO2. This in turn entailed that the large amount of greenhouse gases layered themselves as a protective greenhouse around the planet, thereby preventing the oceans from freezing over.

Mystery solved

Now, however, Professor Minik Rosing, from the Natural History Museum of Denmark, and Christian Bjerrum, from the Department of Geography and Geology at University of Copenhagen, together with American colleagues from Stanford University in California have discovered the reason for "the missing ice age" back then, thereby solving the sun paradox, which has haunted scientific circles for more than forty years.

Professor Minik Rosing explains, "What prevented an ice age back then was not high CO2 concentration in the atmosphere, but the fact that the cloud layer was much thinner than it is today. In addition to this, the earth's surface was covered by water. This meant that the sun's rays could warm the oceans unobstructed, which in turn could layer the heat, thereby preventing the earth's watery surface from freezing into ice. The reason for the lack of clouds back in earth's childhood can be explained by the process by which clouds form. This process requires chemical substances that are produced by algae and plants, which did not exist at the time. These chemical processes would have been able to form a dense layer of clouds, which in turn would have reflected the sun's rays, throwing them back into the cosmos and thereby preventing the warming of earth's oceans. Scientists have formerly used the relationship between the radiation from the sun and earth's surface temperature to calculate that earth ought to have been in a deep freeze during three billion of its four and a half billion years of existence. Sagan and Mullen brought attention to the paradox between these theoretical calculations and geological reality by the fact that the oceans had not frozen. This paradox of having a faint sun and ice-free oceans has now been solved."

CO2 history iluminated

Minik Rosing and his team have by analyzing samples of 3.8-billion-year-old mountain rock from the world's oldest bedrock, Isua, in western Greenland, solved the "paradox".

But more importantly, the analyses also provided a finding for a highly important issue in today's climate research - and climate debate, not least: whether the atmosphere's CO2 concentration throughout earth's history has fluctuated strongly or been fairly stable over the course of billions of years.

"The analyses of the CO2-content in the atmosphere, which can be deduced from the age-old Isua rock, show that the atmosphere at the time contained a maximum of one part per thousand of this greenhouse gas. This was three to four times more than the atmosphere's CO2-content today. However, not anywhere in the range of the of the 30 percent share in early earth history, which has hitherto been the theoretical calculation. Hence we may conclude that the atmosphere's CO2-content has not changed substantially through the billions of years of earth's geological history.

Ok. A hypothesis for the faint sun paradox with backing evidence. Excellent.

However, AWESOME thing that comes out of this is that the CO2 content deduced from the Isua bedrock absolutely blasts a hole in the biomass estimates that were used by Ward for the Medea Hypothesis.

Medea Hypothesis Review Table of Contents

This is the table of contents for my review of the Medea Hypothesis as advanced by Dr Peter Ward in a book of the same name. This is divided in two parts. The first section is a summary of Ward's Medea Hypothesis. The second is my response and critique.


Medea Hypothesis Summary:

1. What is Medean Life?

2. What is Medea Life? (Continued)

3. Medean Paleo Events

4. Biological Diversity Through Deep Time.

5. Biomass Through Deep Time

6. Future Trends in Biomass

7. Ward's Summation

Critique:

8. Misuse of Models

9. Self Contradictions in the Data Presented

10. Misleading Statements

11. Erroneous "Facts"

12. Final Criticism

Medea Hypothesis Review (Part 11): Erroneous "Facts"

This is the second to last posting for the general critique of the Medea Hypothesis. I’m very weary of writing it to be honest and I am delighted that I am nearly done. Here I am going to highlight the last portion I think that needs to be said. That is to say that there chunks of Ward’s data to support his conjecture that are absolutely, flat out wrong. At best, this is sloppy research. At worst, well, let’s skip that thought.

The list of previous posts has gotten to be ridiculous in length. There are ten previous posts and can find them here. The table of contents will be here. The completed Medea Hypothesis Review Table of Contents is here.

In critiquing the Medea Hypothesis, I have commented on where Ward has misused models. I have also highlighted areas where he misleads with his statements, taking facts and spinning them significantly so that he can gets them to point where he wants. Now I am going to point out statements that are, frankly, wrong.

Dawning of the Doubts

Through the methods that strata are laid down, there is an inherent bias towards the present. This is often called the ‘pull of the recent’ because there are simply more data for the recent past than further in Deep Time. This can and does lead to misinterpretations of life’s history. However, on the flip side, it does give us some rather sampling points for the current geological era. The Eocene has a large number of sites that have been documented around the world. Ward’s picture he paints contrasts greatly with more recent work and even contradicts his Medea Hypothesis.

The Eocene mass extinction was significantly smaller than the Big Six (Ordovician, Devonian, Permian, Triassic, Cretaceous, and Modern), but still registered as a big hit for life in the fossil record. During the Eocene mass extinction, the world shifted from a tropical world of palm trees at the poles to a drier, cooler, and more seasonal one. Wyoming lost its crocodiles. The apparent driver of the mass extinction was that transition from hot house to a cooler, drier climate (still warmer than today). Tropical species were forced into far smaller ranges and with smaller ranges come less potential for organisms that are adapted for that climate: think island biogeography writ large. The mechanism for the transition is in dispute, but one that ought to have fit Ward’s thesis, the hypothesized Azolla Event, he completely ignores. The other possible mechanism is that the methane that had been released and drove the hot house world climate was finally absorbed back into the biosphere.

It is far from certain what caused the Paleocene-Eocene Thermal Maximum (PETM) in the first place. It may well have been the methane calthrates that were sequestered in the Greenland Sea. If so, then that methane, produced by life and sequestered there by the unique and interesting deep water conditions, was the biogenic driver of the PETM.

Furthermore, there is a mass of evidence that the PETM ocean was not the stratified anoxic beast Ward paints it to be. Rather that there being no global circulation and upwelling, the nature and location of that upwelling was rather different, in some ways the opposite of now. The upwelling took place in the north and south and the sinking of the waters took place at the tropics with much heavier, higher salinity waters. The bottom waters were hypoxic (low oxygen), but they were empathetically not anoxic enough or unmixed enough for the hydrogen sulfide producing bacteria to have become the vicious killer that Ward hints. Merely having a hot house climate is not enough to trigger a mass extinction.

Modeling deep time through supercomputing assets has matured in the past decade. There are a number of leading personalities in the effort. One of them is Dr Matthew Huber of Purdue. He has been modeling a number of different climates from different snapshots of Deep Time. One of them that he specializes in happens to be the Eocene. One of the interesting implications of his simulations – one that is more than a bit distressing, if true – is that during the PETM, plant life at the equator could not have conducted photosynthesis. It was simply too hot. RuBisCO, the enzyme that photosynthesis is dependent on, stops functioning at 45 C (113 F). It permanently breaks down at 60 C (140 F). If the modeled temperatures are correct, or even close, then it would not have been possible for life to have been what we see at the Amazon today. At best it would have been a desert. A very barren one.

This does need to be verified through the fossil record though and we ought to treat this very cautiously for all the excellent work done by Dr Huber. Modeling is hard and sometimes the results are not what reality really is. However, there is one bit of evolutionary evidence that suggests that Dr Huber is not completely off. What is it? The succulents (and their “ilk” as Ward calls them) originated in the tropical latitudes. These plants include the cacti and other plants that we often associate with the desert. They have their own, interesting variant of photosynthesis called the CAM cycle. The fascinating aspect of this photosynthetic pathway is that it saves up the energy of the sun gathered during the day and then, at night, conducts the temperature sensitive reactions…when the temperatures are lower than the damaging day time highs. This would suggest that the temperature regime that the CAM plants developed in was generally above 45 C during the day time and would fit with Dr Huber’s work. It’s a data point, but an interesting data point. More would be needed to state that Huber’s modeling work was strongly supported.

Timing the Cut of the First Blade

Ward paints a very specific picture of how and why grasses evolved. He states it was because of fall of atmospheric carbon dioxide content that drove the C4 pathway into existence. He even goes as far as stating that the evolution of grass took place 8 or so million years ago during the Miocene. This is wrong.

Molecular data suggests that the C4 pathway originated during the Eocene as the climate cooled and dried out. This was 30 million years ago rather than eight. Furthermore, it appears that rather than being carbon dioxide driven for its evolution, it appears that it was drop in water availability that spurred the evolution of the pathway.

There has been some question cast over the accuracy of the molecular clock as of recent. There is some question as to whether or not the clock is as regular as has been originally hypothesized. If there is a predicted time for X to have arisen based on the clock, then it ought to be possible, if that time period is long enough, to have some fossil evidence to discover. Hence, there is a way to ‘calibrate’ the clock. So where do the grasses first arise? As it turns out, it was not the Cenozoic. Coprolites of the Maastrichtian have come forward with phytoliths. However, whether or not these were C4 grasses or not remains to be seen.

A Medean Mismatch with Paleo Reality?

Timing is key to Ward’s hypothesis. Certain things, biological changes especially, absolutely must happen at certain times for his explanations to happen. As noted, some of those are definitely questionable now. It’s not just the timing that is really important to Ward’s model. It’s also the environmental conditions. Should those conditions turn out to not be as he supposes, then this too calls into question his description of life as Medean.

There is a single problem that keeps coming up time and again with Deep Time environmental work. That is that often the current atmospheric values are used when examining and explaining data from some far flung era. This in some ways comes from the geological premise that the present is the key to the past. This is true and oh so wrong at the same time. The past earth has been a veritable alien planet. There have been significant differences between the now and the then. In some cases this is ecological: the ecology of the carboniferous really was radically different. Sometimes this is environmental in nature: at the time of the Permian Extinction 250 million years ago, there was a 70 C – 126 deg F – gradient in temperatures with a near universal 100% humidity. Almost always it was also the content of the Deep Time atmosphere.

In the past, one of the criticisms laid down at the paleoclimate modeling group that I liveblogged was that you could not get an accurate climate model if you cut and paste current gas mixes into the different continental configurations. The circulation patterns and heat distributions wouldn’t work out properly giving very wrong results.

There has been a flurry of paleoatmospheric work as of late as we further our understanding of how the geochemistry of rock laid down in Deep Time can give us clues as to the content of the atmosphere. One of the basic questions is whether or not the accepted time line of carbon dioxide and oxygen levels that Berner et al have been describing (and Ward has been using as a central point in the medea hypothesis) is entirely accurate. One of the key assumptions has been that there was a massive oxygen crash during the Mesozoic with prolonged periods where the O2 content of the atmosphere dropped down to 11% and was sustained there. Recent rigorous research has shown this to be problematic. A very rigorous experiment to measure the minimum atmospheric oxygen content necessary to support fire was conducted. Using sealed boxes, different levels of oxygen were tested to see if moss would ignite. In the end, it was found that a minimum of 15% was required. This has enormous implications. If there is evidence of wild fire in the fossil record for a given time frame, it is impossible for the oxygen level to have been lower than that 15%. In numerous periods during the Triassic and Jurassic, when the atmospheric oxygen levels were supposed to be 11%, evidence of wildfires was found. This experimental and field data combined call into question the atmospheric models that Ward is relying on to support his Medea Hypothesis.

If the paleoatmospheric data is incorrect, then the paleotemperature data will be as well. It turns out, according to a recent study, that most of the past temperature data for the Archean and Proterozoic were not nearly the broiling hellaceous places that have been described. In fact, the Archean may have been warmer than the Phanerozoic but not nearly as much as Ward paints. Recent research strongly suggests that was the case. Archean rocks that were examined using the analysis of hydrogen ratios indicates that the world, at least at the moments where the rocks were laid down that were sampled were not anywhere near the temperatures that were assumed: they were no more than 40 C rather than 60 C for Ward’s presentation or 85 C for the more traditional view in the deep past.

A Pause Before the Scathing

These are a few examples of where Ward’s work is outright contradicted. This isn’t merely cases of misleading, but true statements. These are errors in fact and ones that could have been easily addressed had he been so inclined. There are more erroneous statements contained in The Medea Hypothesis. However, time and better things to do are pressing on me, so I will leave these three examples as ones as highlights.

My next post will be the conclusion and final commentary. The conclusion and commentary will not be a long post by any means. I will post the table of contents or the whole review before the conclusion, but the conclusion ought to be done this weekend in any case. I am tired of this book and I will be glad of this review’s end. I will consider my next review and write up with more care.

Medea Hypothesis Review (Part 10): Misleading Statements

This is my 10th post on the Medea Hypothesis. (o.O) I am now in the review section of the posts and, unfortunately, this is taking as long or longer than the summarization and reading. Alas. The table of contents is going to be going up shortly. For right now, the previous nine posts are first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth. The completed Medea Hypothesis Review table of contents is here.

Right now though, I am going to touch on how Ward misleads with his presentation of “supporting” data in some cases with respect to the MH. Dr Ward in the Medea Hypothesis misleads in multiple cases. I am going to touch on a few.

The Permian Extinction: The Great Dying

The Permian Extinction was the greatest and most horrifying of the mass extinctions. In the marine realm, potentially as much as 95% of everything died. On land, at least two thirds of all life died and it could be as high as 75%. It has been researched in detail and the mechanisms and causes are fairly well understood. I wrote about what was state of the art in 2006. There have been some embellishments, but, generally, the post holds up fairly well. Please read about it here.

However, Ward recasts the Great Dying to fit his Medea Hypothesis. He squarely lays the blame on life as the cause and driver of the extinction. His description puts the main kill mechanism to be the excretions of anaerobic bacteria. The byproduct is hydrogen sulfide (H2S). It is highly toxic to most aerobic life. He states this is the reason that most life nearly got wiped out: the bacteria ran amok and then poisoned everything else.

Oy.

This neglects the fact that there was a lot going on at the same time. The Siberian Traps were erupting. This is the single biggest eruption in the whole of the past 650 million years and possibly as much as the past billion years. The world radically warmed: well over 10 C in very short time periods. The oceans turned very anoxic. The methane calthrates erupted from the oceans. The ozone layer was destroyed: unblocked UV scorched the land and even the surface of the sea. The vast majority of land desertified. Hypersaline lakes released lethal halogen gases. The atmospheric oxygen levels crashed. Precipitation was probably extremely seasonal and possibly even a megamonsoon model. And, yes, the anaerobic bacteria that Ward cites did play a part and released hydrogen sulfide.

Ward’s bacterial menace was but one of several killing mechanisms. While possibly an important one, the root driver, instigator and maintainer of the nasty situation was not life. It was the vast eruptions that took place in Siberia. Ward states and way overemphasized life’s participation. He ignores and just short of pooh-poohs the others. By doing so, he badly misleads his readers.


The Snowball Earths

The Snowball Earth episodes are time periods in Deep Time where the world is suspected to have virtually iced over. There are detailed discussions elsewhere of what they are. However, they are not necessarily as well understood as Ward paints the picture. Ward outright says that life caused them. His scenario is that life, bacteria and more advanced photosynthetic life drew down the carbon dioxide so much that it caused the earth to lose its greenhouse effect and ice over. Truthfully, this has not been demonstrated. It has been proposed, but the data to back it up has not yet been generated. The rise of photosynthesis, first through bacteria and later through more advanced plants, and the Snowball Earth periods are not well correlated. Chronology is critical to Ward’s narrative and evidence in support of this is definitely lacking. While generally accepted as having taken place on some level, the Snowball Earth scenarios are generally poorly understood. The amount of data available is extremely small since the number of available deposits from these time periods are very few in number. Ward misleads his readers here too as far as what we really know from this time period, never mind whether or not we have a good grip on what was happening.


The Pleistocene Glaciations

Related in his conjectures about life causing ice ages are his speculation on the Pleistocene glaciations. The Ice Age as it exists in the popular mind. Ward again asserts that life caused the carbon dioxide to drop sufficiently for glaciations to take place. Like with the Snowball earth episodes, he makes no case for it, presents no evidence in support. He handwaves and just states it to be the case. We know for a fact though that there is a more complicated story than this going on. Ask Milkanovitch and Croll. Furthermore, Ward ignores some pretty contradicting data: the trend for CO2 does not match his constant downward trending plots. It’s far, far more spiky than his model allows for. Indeed, there have been recent episodes where CO2 was higher than now during those glaciations.

And there's more...I just don't have the energy to go into them for now. The above are good examples. There are probably going to be two more posts in this series besides the TOC. Then , seriously, stick a fork in me, I am so done with dealing with this...faux hypothesis.

Medea Hypothesis (Part 9): Contradictions in the Evidence

Ward draws on many sources to present as evidence for the Medea Hypothesis. Some are papers on the deepest Deep Time of the Earth about the Archean, Protreozoic, and even Hadean eras. Others are models that project backwards and forward both the carbon cycles and the biosphere contents (biodiversity and biomass). He also draws upon the astrobiology realm that he has ventured into several times. Finally, of course, he draws on his rich paleontological background as well. This would seem like an excellent brew for producing a synthesis of ideas about the past, present, and future of the biosphere, which Ward attempted to actually do. However, unfortunately, Ward makes a lot of missteps and pulls together data and models that contradict each other. It can be that scientists often do this, putting a different interpretation on the data, rectifying the contradictions or at least offering proposals how they might be less incongruous by predicted discoveries. Alas, Ward doesn’t offer any such thing.

Some of the contradictions:

1. Franck et al’s carbon cycling model and Ward’s interpretation of the Kasting Methane disaster. The Kasting methane disaster, if it was present, ought to have impacted the global temperature sufficiently to have at least shown up in the model.

2. Ward’s presentation of Archean and Proterozoic Periods as peak biomass periods and the temperature of the world, as he states it, as being higher than the ‘optimum’ for productivity.

3. At what period the peak of biomass was is presented in a contradictory fashion. At different junctures he states that it is the Pre-Cambrian, Cambrian, Devonian through Carboniferous, and Eocene.

4. At what period the peak of biodiversity is presented as is also equally contradictory

5. States that biomass and biodiversity are independent, yet states that the periods with the highest biomass and biodiversity are the same in their respective sections.

There are more, but this is sufficient. For a book of 150 pages, with 103 mostly dedicated to the scientific side of the Medea Hypothesis, there seems to be a nontrivial number of contradictions. He could have addressed the contradictions and ought to have.

For example, Ward could have acknowledged the shortfalls of the Franck model even if this would have opened up more criticism and explained why the model was not addressing the Kasting scenario. Furthermore, he could have given evidence based on the geological record for the Kasting scenario. He doesn’t bother.

This may be sloppiness in his writing. This may be that he hasn’t finished baking the Medea Hypothesis. So far, the mortar seems wet between the bricks. Extremely wet: it's weeping.

More coming, James. Hang on.

For the previous posts on the Medea Hypothesis look here, here, here, here, here, here, here, and here.

The completed Medea Hypothesis Review Table of Contents is here.

The Medea Hypothesis (Part 8): The Misuse of a Model

So, this post is a spin out of my overly long critique post on the Medea Hypothesis. I am trying to condense what I wrote into something more palatable. I realized that my commentary on the misuse of the Franck et al model deserved a post of its own.

First to the scientists and others that are misusing models. For the love of Gawd and all that is good and light (or science, at least), JUST PLAIN STOP!

I am getting exasperated by this. I, personally, dink with models, but it is not my main duty at the day job. I make sure that the computers that the scientists use are up and running. I am privileged to work with people that are developing some really intricate models for simulating a variety of subjects: the world's climate, combustion, qcd, and fusion are a few off the top of my head.

Modeling the biosphere and its interactions with the rest of the Earth system has a moderate tradition Computer models have only become viable for most scientists to use in the past thirty years and the field of earth systematics has only really come into fruition in the past twenty to thirty years. Our understanding of the carbon cycle is ever growing and while the basics have been understood for some time, the devil is in the details.

Modeling for use by scientists up and down the far, far future and into the deepest Deep Time is a relatively young science. There are few researchers working on it. They are even working on it part time and so the ground is largely contested but slowly and the models evolve and countermodels proposed very, very glacially. Getting the various cycles right in their models for the now is very difficult. We still don’t quite have it right even for modern atmospheres and climate change (we're damned close though).

Doing it for Deep Time (and the far future) is definitely a worthwhile venture, but one ought to keep in mind that if we have a hard time working out exactly the details of a world we can sample now then we will have a harder time, with greater inaccuracies, projecting back three and a half to four billion years and forward a couple billion years. The people working on these models realize this. Unfortunately, those outside of the modeling and simulation field often don’t.

Unfortunately, this means a lot of scientists have this problem, since they are not modelers themselves.

In the Medea Hypothesis, Ward relies on Franck et al's model for carbon cycling over multiple billions of years. Franck's model is very simple. It can be run on your desktop or even laptop using Mathematica. The model itself describes how carbon is cycled and sequestered in the earth system. It takes into account continental growth, some biological activity, and even weathering of kerogen. Biomass is represented as a function of carbon dioxide and temperature. It's a nice, simple, useful tool, but its not without its issues.

For example, it cannot take into account the Snowball Earth episodes: nowhere in there can they fit these important planet wide episodes in their model's data (as yet, maybe ever). Furthermore, it cannot account for the temperature fluctuations of the Pharenozoic much at all: the ice ages that have come and gone are not represented almost at all. Likewise, the temperature spikes (Permian, Eocene) cannot be included either. The increase in vulcanism attributed to supercontinental fragmentation is also not included. Mass extinctions that are oh-so important to biodiversity and biomass cannot be included or represented in this data. There are more examples, but this is sufficient for my point.

The nifty thing is that the authors of the model acknowledge this stuff. They made it as a first step, a first brick in the wall to understand how the world works. This is a simple, yet useful tool.

The best analogy for this model is a cube in wind tunnel. Understanding how air flows around the cube is useful. It teaches us a great many things. However, no one working on aerodynamic flows has any pretensions when they are doing anything other than getting simple, basic data from their cube. They certainly are not making proclamations on how airflow will be around a fighter plane based on that cube.

Unfortunately, Ward uses the cube to describe the aircraft and make great pronunciations about the future of life on the planet. This is a mistake. A terrible mistake. The model is far too simple and Ward, being familiar with the observational/paleontological data, ought to know better.

When a model cannot take into account some very fundamental and important events as they pertain to the question of what you are trying to answer, it should not be used.

When a model contradicts key observational data, it should not be used.

It does not mean that the model doesn't have a use. It doesn't mean that this model is junk. This model is an early step in developing realistic models. Everyone jokes about the spherical cow....well...at best, this cow here is a sphere and it is going to be for a long, long time. Even so spherical cows do have their place.

Ward really should know better. Yet he misuses the model anyways. He even builds on it as the foundation of his future projections that the Medea Hypothesis has. This is a mistake and calls into question the Medea Hypothesis as a whole, especially since it contradicts some of his other evidence that he uses for supporting his Medea Hypothesis. There are other problems with the MH, but this is a biggie.

To other researchers. Please. DO NOT DO THIS. Thank you.

For the previous posts on the Medea Hypothesis look here, here, here, here, here, here and here.

The completed Medea Hypothesis Review Table of Contents is here.

Medea Hypothesis Part 7: Ward's Summation

Introduction


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!

The Medea Hypothesis Review: Part Six

A Quick Introduction

This is the sixth post on the Medea Hypothesis. Here I am delving into Chapter 8: Predicted Future Trends of Biomass. The previous posts can be found here, here, here, here, and here. The completed Medea Hypothesis Review Table of Contents is here.This will be the second to last post that summarizes the Medea Hypothesis. The next one will just be Ward’s own Summation (Chapter 9). Then I will do my critique. Afterwards, I will make an index post and then tie all this together on the side bar.

The Medea Hypothesis: Future Biomass Trends.

Based on the previous post and the idea that biomass has already peaked in the past, the obvious conclusion that Ward is going to draw is that the future is going to be a general downward slope for the biomass for the planetary biosphere from here on out. The rason he states is that life is drawing down the carbon dioxide levels over time, sequestering the carbon bit by bit, due to the less than perfect nature of carbon cycle. He bases his future trends and conclusions on the same Franck et al models he did before.

Projected Future CO2 Levels in the Deep Future

However, he gives more background about the history of the future of the biosphere and when life will die out. A long belief up until the 1980s was that life would persist, the whole of the complex life and the biosphere in general until the sun turned into a red giant and consumed the world. It turns out that a number of modelers over time have shown this may not be the case.

The first of these was James Lovelock, the so-called father of the Gaia Theory. He along with coauthors explored the time period that life would go extinct. That pointed out that too much CO2 is bad and that too little is also bad in their 1981 paper in Nature. They predicted that life would, based on the carbon cycle, go extinct approximately 100 million years in the future. They based their projection on when life the atmosphere would drop below 150 ppm of CO2.

Kasting et al followed up on the Lovelock article in 1992. They revised their model which they based on Lovelock’s with the information that had been developed since 1981 in the carbon-silicate cycle. They projected that the so-called critical CO2 point would take place around 550 million years rather than 100 million years. They also pointed out that this critical point would only affect the C3 photosynethic pathway plants. C4 plants and CAM plants would be just fine. However, the total amount of biomass would be decreasing from here on out.

Franck et all started following up in 1999. Their results varied with the error bars placing the critical 150 ppm CO2 550 to 850 million years from now. They also projected the global productivity was already falling and would continue to do so, reducing the complexity of life and the total biomass until its final extinction. The end, when it comes, they projected would come as a whimper rather than a bang.

There have been others that have worked on the same problem. They all, according to Ward, give predictions that the critical CO2 level will come between 500 million years from now to 1.5 billion years from now.

What Would the Deep Future Look Like?

Ward then discusses the differences between the different photosynthetic pathways. I’ll just link to C3 photosynthesis, C4 photosynthesis, and CAM photosynthesis. You can read about them there much better than I can write about them. He also states that the evolution of C4 plants only took place eight to ten million years ago (pg 119). C4 plants need a minimum of 10 ppm CO2.

“The formation of new photosynthetic pathways is a sure sign that long-term reduction in atmospheric CO2 is having a profound affect on the biosphere. The continued long-term reduction in CO2 over next hundreds of millions of years should produce a decisive change in the global floras.”

Pg 119, Chapter 8: Predicted Future Trends of Biomass.

Ward speculates that the world will transition gradually from C3 woody plants to C4 and CAM plants: he refers to CAM plants as “succulents and their ilk.” He posits that it is possible the world will just be grasslands which will be less productive than the forests of now. Then he also points out that there are ‘trees’ that are C4 plants: bamboos and palms. The forests may be still be present, just as bamboo and palms rather than the types of trees we are familiar with.

He accepts that it may be possible plants will develop other photosynthetic pathways to adapt to the ever lowering CO2 levels. He dismisses this as eventually they too will succumb to the ever lowering CO2 levels as well.

Ward paints a picture of what will happen when plants finally go extinct. The soils will cease to exist. Weathering will drop. The nutrients from plants that oceanic life depends on will cease. Life will slowly collapse even in the oceans to much simpler life. He basically posits a reverse Cambrian Explosion – an Antephytozoic Implosion. Complex life will all but end. Life will be reduced to microbial in nature very quickly. Once plant life goes extinct, Ward cites David Catling as stating that within 15 million years that after the extinction of plants that the atmospheric oxygen content will drop to 1%. This dooms animal life.

Wrap Up Of Future Trends

Ward blames life for the supposedly broken carbon cycle. He states that this supports the Medea Hypothesis and Chapter 8 is the predictions of the Medea Hypothesis. The next post will be a summation of the Medea Hypothesis. I will be pretty much just quoting Ward. It’s less than two pages to type in.

What is the Medea Hypothesis: Review Part Five

A Small Introduction

This is my latest post on the Medea Hypothesis as proposed by Dr Peter Ward of the University of Washington. The hypothesis is a counter to the more mainstream, if misused, Gaia Hypothesis. The Gaia Hypothesis states that the world is a self-regulating system with compensatory feedback systems to prevent or at least dampen, runaway effects. The primary instrument of the system in the Gaia Hypothesis is life and its interactions with the environment. The Medea Hypothesis is a rejection of that idea and in its place proposes that life does not, in fact, dampen the effects of runaway processes, but rather amplifies them. The short and perhaps overly dramatic version is that life is suicidal.

I have posted summarizing the Medea Hypothesis in several previous posts. You can find them here (introduction/competing theories of life), here (summary of what Medean Life), here (Paleo Medean Events) and here (biodiversity through time). The complete Medea Hypothesis Review Table of Contents is here.

The main theme of this post is a summary of biomass through time and that the Medea Hypothesis predicts that over time, biomass will fall from past peaks due to the interactions and evolution of life. This is based on Chapter 7 Biomass Through Time as a Test and takes a small amount from Chapter 8 Predicted Future Trends of Biomass in the book of the same title. Again, I am going to minimize the commentary until after. This is where it is actually hardest to do so since Ward relies very, very heavily on computational models. Now that I have had a lot more sleep since we all got sick and the holiday, plus some commentary from Carlos (thank you!), I have developed some pretty strong opinions on the subject. I will attempt to avoid interjecting them and save them for the criticism post…which is coming quite soon.

If the post seems a bit different than the others, it is in part due to the fact that it took a while to pull together everything so that I could write it. I took notes, rather than reading directly from the book, and had more time to ponder the narrative. That may be good or bad.

The Tolkienesque Decline of Biomass Through Deep Time

The Medea Hypothesis conjectures that life works in contrary to its own interests. In this case, biomass, it actually works over time to reduce biomass through its interactions with other life and the environment. Ward predicts that biomass was actually more in the past – two potential times, the Devonian, just after the evolution of forests and the the Cambrian, just after the evolution of animals – and has been in decline ever since. Ward does note that it is very difficult to measure biomass through deep time though. He suggests that there are proxies that work to be able to model life’s biomass.

Biomass is limited by several things, but there are three that Ward specifically identifies and elaborates on. The first is energy. If there is not sufficient energy coming into the system where life resides, there is a very little life possible. The second limiting factor is the amount of nutrients available. The difference between a bare rock environment and the soil of any temperature climate are excellent extremes: one is highly nutrient rich and supports a cast of living characters that is quite extensive and the other is very, shall we say, barren, in comparison. The final example item that Ward narrows in on that limits biomass is temperature. The Arctic has a far more limited biomass than does the tropics. Ward cites temperature as the reason.

Energy has increased over time as far as the sun’s input into the world which would argue that there is an increased biomass as related to the solar input. However, early life was not photosynthetic. A lot of it consumed the primordial chemicals that were left over from the world’s formation. This is supposedly an easier to consume form of energy than photosynthesis. Early life ran through and consumed all this easily available nutrients and caused a crash. Theoretically. A lot of this is based on modern conjecture and the modeling work of S Franck et al. To be discussed below. This caused a biomass crash until photosynthetic based energy systems take over. Because there was a crash, a life induced biomass reduction, this counts as a Medean Effect.

Nutrients tie into this. Life Ward claims that carbon dioxide is actually the most important nutrient and the one that is the biggest clue to biomass over time is actually carbon dioxide. He makes the argument that the higher carbon dioxide levels in the past were indicators of a high biomass. The reason that he argues this is that there was far more carbon dioxide – his key nutrient – therefore there was far more potential for life to exist. During the Pharenozoic, the CO2 levels have dropped significantly. This means that the potential for life – according to Ward – has dropped. The cause, Ward states is because life is slowly sequestering the carbon: carbon cycle is broken from his point of view (strongly implied). Ultimately, this will be what dooms life according to Ward: the CO2 will run out because life will have sequestered it all.

Temperature is the final of the three limiting factors that Ward discusses in some detail. This is the one that he talks about the most. He states that 70 C is the upper limit for life to exist and be productive on a large scale. 0 C is equally bad. The ideal from his point of view for biological productivity is between 20 C and 70 C. The Pharenozoic has had a temperature band of 15 C +/- 10 C on average. Trace evidence, especially isotope ratios and the types of minerals in the sediments are the evidence for the temperatures in the Pharenozoic.

According to Ward, the traditional view of the temperature evolution of the world went something like this. Around 3.8 billion years ago, the world cooled to around 80 C. It then cooled to approximately 40 C around 3 billion years ago. Sometime around 2 billion years ago it cooled to about 20 C: near the Pharenozoic temperature band. After that, never rose above 30 C.

He counters that new research using ‘pristine cherts’ – that not altered by subsequent geological events – indicate that the temperature changes were rather different than what the ‘traditional’ view is. The time steps with temperatures he cites are 70 C at three billion years, 60 C at 2 billion years, and 40 C at 1 billion years.

Ward then relies on Franck et al 2006/2002/2000 papers to back his claims on biomass. The microbial ecology that existed prior to the evolution of complex life is in the models as sustaining biomass at a higher rate than the subsequent ecologies. It was some form of steady state or near to it in their models. Their ideal temperature for productivity is 40 C. The actual peak of biomass according to the Franck et al model was just after the evolution of complex life.

[figure to be added on Sat]

Based on figure 7.3 from the paper, (see above, tomorrow morning), Ward argues that biodiviserity and biomass are divorced from one another. He goes on to use the Franck paper to to argue that life made jumps in biomass with each breakthrough in exploiting a new energy resource and that afterward a slow decline would take place until the next energy source was ‘found’ and exploited. He implies that there are no more energy sources to exploit for another breakthrough.

Part of his argument is wrapped up in the idea that at the time of the Edicarian/Vendian fauna there was a fundamentally different form of ecology present. The world was covered in bacterial mats. This is demonstrated through the Ediacarian fossils themselves. They were lain down in sandstone and that makes it terribly hard, if not impossible so says Ward, to preserve soft tissue like those fossils have. He uses a class of his to demonstrate how they were created. If there was a bacterial mat under the dead organism and then another ground on top when it silted over quickly, then you would be able to get the fossils as seen. Otherwise, they will decay and not produce fossils. Because bacteria were so common, and able to form the mats, the biomass was higher then. This is the proof that biomass was higher then.

Conclusion (for this post):

Ward then states that the biomass peak, in his opinion, was between the evolution of forests until the Eocene. This is a bit confusing because of what he argued just prior. Ward argues that life caused the temperature drop and that this is due to its Medean nature: by absorbing CO2 as it does, causing a breaking of the global greenhouse, life is dooming itself.

Post Epilogue:

That tackles the Ward’s arguments about biomass through time. He goes on to the next chapter describing what the future of biomass is. This is bound up in Franck et al’s model again. I think I will tackle that as a separate post. I have most of the notes already, but it needs a few more bits to make me even close to happy with it.

What is Medean Life Part 4: Biodiversity Through Time

As some of my blog followers have been noting that I have been posting on the Medea Hypothesis as posited by Dr Peter Ward in his book of the same name. I have been working my way through what I think are the relevant parts and posting summaries (and quotes) from them. The first post about what the different hypotheses, Gaian and Medean, are. The second post covered what would make life Medean, rather than Gaian, is here. The third post is about the Medean "Events" of the past. Originally, I had planned to do this fourth post on biodiversity and biomass through deep time and into the future. I realized though that biodiversity through time and biomass through time are independent subjects and ought to be covered separately.

The complete Medea Hypothesis Review Table of Contents is here.

This time we are tackling biodiversity through deep time.

Ward paints three different possible scenarios of how biodiversity could exist through time.

Scenario One: Ever Increasing Complexity & Diversity


The first one is where over time, life has become more and more diverse. Life is growing ever more diverse and ever more complex in its interactions. The ecology through time has been becoming more and more complex in the methods that life extracts energy from its environment. As more complex ways are evolved, more opportunities for further niches arise which in turn life moves on to occupy.

This has been the relatively traditional view that the scientific field has held. In fact, it's held this since the 19th century. Work up through the end of the 20th century appears to have confirmed it. Specifically, it has been supported by the work of the late Dr Sepkoski. His work is based on surveying the scientific literature and picking up the named genera. This work has, iirc, continued by successors.

The biggest critique of this view is what is called the "Pull of the Recent." What is that? The problem cited is just the fact that the more recent the sediments, the more common they are. There are more locations for Pleistocene fossils (what is popularly called the Ice Age) than there are for Eocene (the hot house 35 million years ago). The further back in Deep Time you go, the lower number of locations where fossil bearing sediments are available. Therefore, you will get a bias to the present. Or at least will be biased to whichever eras have the most locations. Or have been the most collected from. or...There are a number of good criticisms. More later.


Scenario Two: Diversity Plateaus

The second view is that at some time in Deep Time, life hits diversity plateaus. That is to say that at different times, life had innovations that allowed it to diversify and then hit some inherent limit within the ecology: it was impossible to diversify more because all the potential niches were occupied.

Where these plateaus are is a very contentious issue. Some work indicates that the Late Paleozoic was as diverse as now. Other research suggests that the peak was actually in the Late Cretaceous as part of the Cretaceous Ecological Revolution with the introduction of flowering plants. Still others argue that life hit a step function at different times. The Paleozoic, Mesozoic, and Cenozoic were each more diverse than the last. The work, in general, is pretty new. Paleontologists are more collectors and analyzers of animals and only a handful - a very argumentative group at that - study the larger issues of diversity and ecology in Deep Time. I find the same names from 30 years ago that are arguing about it now when digging through all of this.


Third Scenario: Peak Diversity is Past

There is another, very heretical (ie not accepted) view that the diversity of life hit its peak in the past. Ward argues that, in fact, that life actually hit its peak during the Eocene as far as its diversity and we are now in the long slide to ecological simplification. Think of the old simple curves they used to do for civilizations (Toynbee's Organic Cycle of Civilizations? I think?): there was a period of youth where they would grow and expand. This was followed by a mature stance or period where expansion stopped, but maintained itself. Then, old age sets in and contraction sets in and ultimate decline, fall, and extinction follow. While not exactly excepted much in history studies these days, Ward presents that the decline stage has already set in. He asserts that life is the cause of its own decline in biodiversity. This makes it Medean.

His arguments for the passing of the peak of biodiversity fold into the next post: that biomass has been declining through time and life is the cause. We'll cover that in the next post.

What is Medean Life (part 3): Medean Paleo Events

This is my third post in my consideration of The Medea Hypothesis. I am trying to go through and summarize what Dr Peter Ward puts forward as the hypothesis and what proof he is basing it on. My previous posts are here and here. The Medea Hypothesis review is complete and the table of contents is here.

The basic premise of the Medea Hypothesis is that life is suicidal and will exterminate itself by resource overuse and that it produces far more, or induces far more, positive feedbacks than correcting negative feedbacks. The negative feedbacks, he feels, are absolutely necessary for the Gaia Hypothesis to work. The Medea Hypothesis is a reaction to the Gaia Hypothesis and proposed as an alternate.

Ward proposes that certain events in the evolution of life, in deep time, that support the Medea Hypothesis. I am going to run through them now. I will quote as much as possible and try to summarize otherwise. This is by and large encapsuled in Chapter 5 of his book.

I am going to make a comment. I cannot help it. Forgive me. I have been trying to save it for the end. However, I think in this chapter, Ward moves his goal posts. Before he talked about biomass being decreased over time and now he's stating, in Chapter Five, that biodiversity is actually the key: "Let us begin this chapter witha first proposal about what will be called Medean events - life-driven episodes that result in a drop in the diversity of abudandance of subsequent (later generation) life." (pgs 72-73)

1. DNA Takeover: 4.0(?) - 3.7(?) Billion Years Ago.

"Unfortunately, unlike the later events, which are based on data from stratal and fossil evidence, this first Medean event is no more than an educated guess. Many of us believe it to be true, although since ther is currently no way to scientifically test this hypothesis, it must remain an educated guess, and no more.

"Over the past several years, biochemists conducting experiments to find possible alternatives to our familiar Earth life have attempted and in some cases have succeeded, in producing DNA with exotic "languages," obtained by changing the number of nucleaotides used to code for a specific amino acid. Thus it is possible - indeed, I believe likely - that early DNA life on Earth might have come in a vaierty of forms, perhaps all slightly different from our now familiar DNA. If so, it is probable separate kinds of DNA competed against each other. [...] [I]t is probable that there would have been intense competition betweene ach of the kinds of DNA, competition that would have been inherently Darwinian. The suppression of other kinds of life would have followed, and if so, this would have been a Medean Event, in fact, the first example of a Medean event: the takeover of a single kind of life. Elsewhere I have followed other evolutionary biologists in supposing that the highest diversity of life, the most basic kinds of life, not species was surely early in Earth's history. "

pgs 72 -73.

In essence, boiled down, that our variant of DNA life outcompeted the other versions of life, whatever they may have been or even if they did exist, makes it Medean. It reduced the potential of life in the future by being competitive such that it wiped out everything other than itself.

2. The Methane Disaster, 3.7 million years ago [sic] (ought to be 2.7 billion years)

"The methane atmosphere hypothesized to have been present on the early Earth may have been a byproduct of the first life, a waste product of its metabolism. Life was present as a series of oil-like slicks and stacked bacterial layers and sediments, called stromatolites. Although individually small in size, these microbes became globally abundant and in so doing began to change the planet. This is the conclusion of the eminent atmospheric scientist and astrobiologist James Kasting of Penn State. His new work describes how the formation of methane-producing life on Earth nearly ended the saga of life on our planet in its earliest epochs by creating a cold buffer on the surface of the planet. The formation of the methane haze took an already cold world (the Sun was more than 30 percent less energetic) and added a layer of clouds for the first time that reflected heat back into space. But for the very high volcanic heat flow on our planet, this type of condition made the planet much worse for life's survival. [...] In any event, this by-product of cooling clouds is not the predicted course of events under the Gaia hypothesis. This is the first test that shows how earliest life nearly ended its own history through its formation."

pgs 74-75, Chapter Five: Medean Events in the History of Life.

The paper which Ward is basing his conclusion on this paper. This is one that I will be commenting on later. I added the link to Dr Kastings' page.

3. The Rise of Atmospheric Oxygen, 2.5 Billion Years Ago - Chemical Weapon of Mass Destruction.

This is simply the oft talked about Great Oxidation Event. Life developed 'modern' photosynthesis. The oxygen poured out to wipe out or marginalize most the rest of life. Ward states:

"Oxygen caused a massive mass extinction on planet Earth: the biovolume of life on the planet plummeted. This is a Medean result. Only the children of the bugs that could tolerate oxygen - and the cyanobacteria that learned to make it, and the bugs that later learned to breath it - would thereafter enoy the sunlight."

Pg 75

4. The First Global Glaciation, 2.3 Billion Years Ago - Life Causes the First Snowball Earth

The idea is that life developed photosynthesis and it sequestered the carbon to such a degree that this 'broke' the early greenhouse that warmed the earth under the fainter sun: the sun let off a nontrivially lower amount of radiation. This is normal for a star's evolution. This caused the near world coating ice age that has been proposed as one of the Snowball Earth events. The Snowball Earth event would have nearly wiped out life. Because it did and had the potential to do so, if it was caused by life, it was a Medean Event. Ward states that it was.

5. The Canfield Oceans, 2 - 1 Billion Years Ago (?)

The so-called Canfield Oceans are particular state that the oceans have developed into a few times through Deep Time. The oceans become stratified: that is that they differentiate into different levels that do not mix. When this happens, the lower depths become hypoxic - low in oxygen - and can often even become anoxic: lacking oxygen almost altogether. When this happens, certain types of anaerobic bacteria settle in to grow. One of these types of bacteria produces a very nasty chemical, hydogen sulfide. Hydrogen sulfide is very, very toxic. It kills most other life. Ward maintains that this dominated and existed for nearly a billion years - and in several mass extinctions - is a Medean Effect.

6. The Second Snowball Earth, 700 million Years Ago

Ward maintains that life, once again, caused the second snowball earth scenario 700 million years ago and that it was made worse by the increased continental area: this had the potential to wipe out life and was "caused" by life. Medean effect again.

7. The Rise of Animals, Reduction of Life, 600 Million Years Ago

Ward maintains here that the rise of animals with their carnivorous and herbivorous ways reduced life by taking nutrients, carbon specifically, out of the nutrient cycle. Animals were so effective at this that they caused a drop in the atmospheric CO2 content and a massive reduction in global temperature.

The rise of animals that so spectacularly ocured during the 540-500 million year-old "Cambrian Explosion" is deemed one of the great evolutionary events ever to have affected the Earth. Clearly the number of species on the planet radically increased. But what of the biomass? Just the opposite seems to have occured. Concomitant with the rise of animals and higher plants, there is a drastic reduction in the number of stromalites and other evidence of layered bacterial slicks. The evolution of herbivores and carnivores among the emergent animals was a major reasons for this. The fecal pellets of the newly evolved zooplankton - little animals that feed on plankton and other microorganisms - stuck together and formed slime balls that readily sank down to the abyssal depths, removing organic carbon and nutrients from being recycled by way of photosynthesis. Thus, we can view the evolution of complex life on our planet as Medean since it led to a reduction in the total biomass.

This biomass reduction was probably caused not only by herbivorous success of the newly evolved animals. There may have been a significant drop in global temperature as well - in fact the largest single drop in planetary temperature in Earth history, if the modeled results are correct.

pgs 79-80.

Note: this is based on Franck et al 2006 which is based on Franck et al 2002. There will be a critique of this later.

8. The Phanerozoic Microbial Mass Extinctions, 365 - 95 Million Years Ago

[really ought to be described as the return of the Canfield Oceans by Ward]

Ward lays the blame for the Devonian, Late Triassic, and Permian Extinctions - as well as several lesser mass extinctions at the door of Canfield Oceans. He feels that the hydogen sulfide by-product of microbial life is the primary kill mechanism for these extinctions. That is a Medean Effect.

9. Rapid Global Temperature Changes Due to Colonization of Land by Plants, 400 - 250 Million Years Ago

Plants colonized the land and as they adapted to their new environment they started doing two things. The first was that they started sequestering more and more carbon, especially through the carboniferous period (which I spoke of here) and also because they promoted the weathering of rocks far faster and that in turn caused the carbon dioxide to be drawn down as well. This caused global cooling on a massive scale and that in turn caused glaciations. Life became harder, the environments for ocean life was reduced (because the continental shelves were exposed because of the glaciations) and the amount of carbon available for life became less. This would be Medean behavior.

10. Devonian Eutrophication Events, 360 Million Years Ago

Eutrophication events are ones where algae or plankton bloom in response to greatly increased nutrients in the waters. When this happen, they boom so greatly that they actually deplete the nutrients. This causes a die off and the bodies of the plankton and whatnot fall to the ocean floors. This in turn causes the ocean bottoms to slowly be rendered anoxic. Slowly, but surely - at least theoretically - life would slowly turn the oceans anoxic up to a very high depth, even in the absence of high temperatures. Ward maintains that this happened on a massive, even global scale during the Devonian, possibly as a response to the greatly increased nutrients coming off the continents from relatively recently developed forests. Ward maintains this helped drive the Devonian Mass Extinctions, ff this were true, then this would be another example of a Medean Event.

11. The KT Extinction, 65 Million Years Ago

By the end of the Cretaceous there were planet-spanning forests. One effect of the [Chicxulub Impact] was the ignition of continent spanning forest fires. This produced an enmorous amount of ash that filled up the atmosphere. This soot, a product of life, caused global cooling for some months after the impact, which seems to have played a significant role in the kill mechanism. Again, a Medean Effect.

12. The Pleistocene Ice Ages

Ward blames them on the draw down of carbon dioxide from the atmosphere by life.

13. Humanity.

Ward states we are the ultimate Medeans. He dedicates a whole chapter to us.


That wraps up the What Is Medean Life Part Three. Next up is biomass through time and the future of life. Sorry this is taking so long. Life is...busy. Commentary will followafter the next post.

What is Medean Life? (Part Two)

This is the second post in my consideration of The Medea Hypothesis. I am slowly working my way towards a commentary and criticism of the tMH. Please be patient. I have alot going on. It's finished and The Medea Hypothesis Review TOC is here.

Dr Peter Ward in his recent book, The Medea Hypothesis, proposes a counter point to the popular and often misinterpreted Gaia Hypothesis. In a previous post, I quoted Ward as to what he considers to be the main characteristics of Medean Life. There are three that are really, really worth reiterating plus one that was missed because it wasn't with the other defining traits of "medean life:"

1. Life is NOT a part of a self correcting or self regulating system. Life is actually suicidal and that life's interactions with the environment mostly, by and large, make it less friendly for life's continued existence.

2. Diversity of life is completely divorced from the total biomass. In fact, a lot of what Ward seems to argue is that the more diverse life is, the less biomass there is. Over time, the total biomass is decreasing due to life using up its available resources and as a consequence (or so I am interpreting his writing) the diversity increases as life must find new ways of exploiting what's left.

3. Every time a 'breakthrough' takes place for life in either exploiting some new energy source or some new way of organizing itself, there's an initial BOOM of biomass and then a drop off with a steady decline over time following.

4. Resource plundering/competitive poisoning (hyper-darwinism?). This one wasn't mentioned earlier because it wasn't with the standard definition section of what Medean Life was supposed to be. All life takes, hoards, plunders resources to the detriment of all others and often poisons everything else around it to further its advantage. The anaerobic bacteria that produces hydrogen sulfide is a good example. The black walnut or eucalyptus is another pair. Humanity is the pinnacle of this, but not an exception like is normally portrayed. Oceanic eutrophication (hypoxia/anoxia of the lower depths) is another example according to Ward, although, he breaks it out into its own category, it really is just another example of plunder/poisoning.

So if these are the basic characteristics, boiled down and as interpreted by me, what are the feedbacks that life is producing to make things worse for itself. The main feedback cycle that is on Ward's mind is the carbon cycle and global warming. With his experience with the Permian Extinction, the writing of Under the Green Sky and his upcoming book The Flooded Earth, global climate change looms large on Ward's mind these days. It is Ward's hypothesis that positive feedback cycles predominate the carbon cycle. Here are the ones he lists:

1. Increased atmospheric carbon dioxide increases photosynthesis. This increases carbon sequestration (negative feedback, CO2 goes up, amount of CO2 sequestered corrects for this, at least somewhat)

2. Increased temperature (from increased CO2) leads to increased soil respiration, which moves a lot of the organic carbon in the soil into the atmosphere (positive feedback, warmer leads to more carbon coming from soil, which leads to warmer still)

3. Warmer temperatures increase fire frequency, which replaces older trees with younger ones, which in turn releases more carbon into the atmosphere (another positive feedback)

4. Warming may lead to drying, which will cause greater desertification which will in turn cause sparser vegetation which will increase dust clouds and over all planetary albedo, causing cooling (negative feedback)

5. Higher atmospheric carbon may cause increased selection for drought resistant vegetation which will cause more intrusions of shrub and other dry climate resistant plants intruding into desert regions which will decrease albedo and dust clouds (positive feedback)

6. Warming leads to tundra being replaced by boreal forest. This decreases planetary albedo (positive feedback)

7. Warming soil produces more methane than cooler soil. As the world warms, the soil produces more which warms the earth more. (positive feedback)

8. Warming soil increases the production of Nitrous oxide (positive feedback)

9. Warming polar regions cause release of methane and carbon dioxide buried in the peatlands, etc. (positive feedback)

The Medea Hypothesis, Chapter 4, Medean Feedbacks and Global Processes, pages 57-58.

What Ward doesn't mention here also is that the models he is relying on for the Pre-Phanerozoic and into the future, deep future, are based on the level of CO2 being higher in the past, much higher. In fact, he states that the main suicidal tendency of life is the using up and drawing down of the carbon dioxide levels. A form of biological plundering, if you will. Finally, Ward states that there is no way to directly measure the carbon dioxide content of the paleoatmosphere and therefore the models are essential and predictive (red flags there, but we'll get there at the end of the Medean Life posts when I do some commentary).

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.