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.