Science Literature

Over the years, samples of amber recovered from numerous sites around the world have been found to contain petrified insects, plants and a variety of other exotic inclusions. Invariably, we get an insight into a past world where the flora and fauna look very modern. A recent discovery has identified mammalian hair in amber, whose original owner was a contemporary of dinosaurs.

The shape and structure of mammal hair has remained unchanged since the Cretaceous (Source here)

The dimensions and topography of the two fossilised hairs were analysed carefully, because the find provides the first opportunity to look at Mesozoic mammal hairs preserved in 3D. The result:

"With such features, the cuticular surface of the Archingeay-Les Nouillers hairs shows a modern aspect, implying that the morphology of hair cuticula has remained unchanged throughout most of mammalian evolution."

The New Scientist report says this is the first time researchers have been able to study the pattern of scales on their surface:

"It turns out that the pattern is identical to that found on modern mammalian hair: rows of overlapping scales stacked on top of each other in an orderly fashion, with each row roughly 2 to 8 micrometres high. This discovery is "wonderful progress", says Zhe-Xi Luo, Curator of Vertebrate Paleontology at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. "It shows the microstructure of hairs of mammals have always been the same.""

Why is this find worthy of comment? Many people have been brought up to think that the earlier we go back in the fossil record, the more strange the flora and fauna become. Whilst something can be said in favour of this view, it tends to hide the phenomenon of stasis. We do find animal radiations, diversification and extinction, but accompanying this change are pervasive evidences of continuity. The first mammals are thought to have appeared in the Late Triassic, and the first fossilised animal hair is dated as Late Jurassic (preserved as carbonized filaments). Now we find that the Early Cretaceous hair is essentially modern. It is an example of continuity across the geological Periods. It is an example of stasis. It is also an example of the abrupt appearance of complexity.

Mammals lived through the "Age of the Dinosaurs". As time goes on, it is apparent that the diversity of Mesozoic mammals is greater than used to be thought. An example is Castorocauda, from the Middle Jurassic Jiulongshan Formation of Inner Mongolia. This animal is well-preserved and shows specialisation in the fur:

"Castorocauda is preserved with a pelt (guard hairs and under furs), making it the most primitive-known mammal to be preserved with hairs. Carbonized in the fossil, the short and dense under-furs were to keep water from the skin; the longer guard hairs are preserved as impressions on the fossil slab." (Source here)

Mammals are now recognised to have occupied more varied ecological niches than was previously recognised. Castorocauda had specialized skeletal and soft-tissue features for swimming and teeth for eating fish. It is thought that many were ground-living, and a recent discovery is of mammals living in burrows and being prey to digging dinosaurs:

"Two fossilized burrows were spotted nearby. When compared with other burrows researchers have uncovered over the years, the size and complexity of these newfound ones suggest they belonged to mammals - the smaller burrow to a mouse-sized creature, the larger one to a guinea-pig-sized animal. The fact these fossils are so close together suggests they are evidence of dinosaurs scrabbling down to prey on mammals, the researchers suggested." (Source here)

It was a different world - but much that was present is still found today and a gradualist origin of complexity is not confirmed.

Mammalian hairs in Early Cretaceous amber
Romain Vullo, Vincent Girard, Dany Azar and Didier Neraudeau
Naturwissenschaften, 97(7), July 2010, 383-387 | doi 10.1007/s00114-010-0677-8

Abstract: Two mammalian hairs have been found in association with an empty puparium in a 100-million-year-old amber (Early Cretaceous) from France. Although hair is known to be an ancestral, ubiquitous feature in the crown Mammalia, the structure of Mesozoic hair has never been described. In contrast to fur and hair of some Jurassic and Cretaceous mammals preserved as carbonized filaments, the exceptional preservation of the fossils described here allows for the study of the cuticular structure. Results show the oldest direct evidence of hair with a modern scale pattern. This discovery implies that the morphology of hair cuticula may have remained unchanged throughout most of mammalian evolution. The association of these hairs with a possible fly puparium provides paleoecological information and indicates peculiar taphonomic conditions.

Most of the time, scientific research seeks to build on theoretical foundations that have been carefully constructed by the wider research community, often over many years. If a theoretical framework is found to be robust, it gains widespread assent, with few interested in challenging it. Those who are attracted to the idea that science develops progressively are the least likely to talk about challenges. For them, any change is a minor modification of the theoretical edifice. Thomas Kuhn referred to these theoretical frameworks as 'paradigms', and the progressive refinement of that framework as 'normal science'. Kuhn pointed out that anomalies do not trigger the practitioners of 'normal science' to question the paradigm, but they either treat them as problems waiting to be resolved, or they ignore them altogether. In recent months, I've become aware that this phraseology and understanding of scientific activity is intensely irritating to some scientists. They appear to regard such talk as an invention of outsiders with a subversive agenda. A desire to comment on these issues has stimulated this blog, which is based on a paper authored by Walter Alvarez, an experienced and respected scientist working in the field of geology. He introduces his paper thus:

"Lightman and Gingerich (1992) argued that when a ruling theory is successful in accounting for a wide range of observations, scientists ignore observations that are not explained by the theory. They argued that such "anomalies" are only "retro-recognized" when a modification or replacement of the original theory calls attention to and explains the conflicting observations."

The "ruling theory" has been referred to above as the theoretical framework or paradigm. The quotation points out that anomalies tend to have a very low profile until solutions are found, and then the solutions are publicised widely to hail the success of the paradigm. Earth scientists generally understand paradigms. Many have lived through the Plate Tectonics revolution - which is now the ruling paradigm. Alvarez considers that a major revision of this paradigm is needed, and he points to the relevant anomalies that show all is not well.

"Such an anomaly is present in the plate tectonic theory that has dominated geological thinking for the last 30-40 yr. Plate tectonics sees subduction as able to consume an unlimited amount of dense oceanic lithosphere, but unable to continue after convergence brings two buoyant continental masses together. Buoyancy should terminate the convergence, with a new subduction zone initiated somewhere else, where it can consume oceanic lithosphere. This view persists despite evidence that at least some continental collisions have continued long after the continents first collided."

Within plate tectonic theory, there are two categories of mechanisms for driving the crustal plates: boundary forces ("slab pull" by descending plates and "ridge push" (emanating from centres of crustal generation) and drag forces (frictional forces between mantle convection cells and crustal plates). These concepts are introduced to students very early in their studies, and they have become entrenched. For examples, go here and here. For a more advanced treatment, go here. The relative contributions made by these different forces have been much discussed by scientists developing plate tectonic theory. However, firm conclusions have not been reached. If there is any consensus, it is that boundary forces are more significant than drag forces, and that slab pull is more significant than ridge push. Alvarez has the view that with plates carrying continents, drag forces are of major importance. He discusses three cases where plate movements continued long after two continental masses collided. If boundary forces were dominant, motion would cease very quickly. However, if drag forces were significant, the problems disappear. Alvarez started publishing along these lines in 1982 and claims his recent research confirms the earlier hypothesis.

"More than 25 yr ago the present author proposed that protracted collisions may be driven by traction applied at the base of deep lithospheric roots (Alvarez, 1982), and in two subsequent papers (Alvarez, 1990, 2001) used the term "continental undertow" to refer to this driving mechanism. [. . .] Although the data available at the time were insufficient to test the undertow model, there are now many relevant observations. The last section of this paper shows how the anomaly of protracted collisions can be explained by continental undertow."

It is not my intention in this blog to discuss the wider implications of the Alvarez model. My interest is in the way scientific theory develops, the way anomalies are handled and in the (often hidden) influence of dominant paradigms. What we find here in the earth sciences is frequently encountered in the field of evolutionary biology. There are many anomalies between observed data and theory, but these are typically well-known only to researchers close to both. Anomalies (in the main) do not get published until someone proposes a solution - within the ruling paradigm. In plate tectonic theories, anomalies surround the quest for driving forces able to move crustal plates and build mountains; in evolutionary biology, anomalies are pronounced when it comes to explaining how complex specified information is derived from natural causes. Darwinian mechanisms are useful for explaining antibiotic resistance but not the origin of the immune system. They are OK for changing the dimensions of finch beaks but not for constructing beaks. They have some value in elucidating industrial melanism but not for engineering structural colour in moth wings.

Wonderful music, but is there a composer? (Source here)

Researchers who propose paradigm-changing solutions do not find it easy to get their work past editors and reviewers. Intelligent Design (ID) requires a fundamental change of paradigm in the way we think about causation. Most research relating to origins admits only natural causes (naturalism), whereas ID links complex specified information to intelligent agency. ID researchers consider this is an issue that must be evaluated within science, but there are many who think otherwise! This is why Stephen Meyer's peer-refereed paper led to the removal of Richard Sternberg from the role of editor of the Proceedings of the Biological Society of Washington and the subsequent withdrawal of the paper. Other examples of editors (in other disciplines) in trouble because they were willing to publish papers that challenged the dominant paradigm were given in an earlier blog. Although there is a continuing polemic by ID-denigrators based on the supposed lack of peer-reviewed ID research, the situation is slowly changing. Nevertheless, the most important thing to realise is that the playing-field is not level and there are far too many people defending the dominant paradigm for ideological reasons. Their style of engagement with the issues suggests they are not interested in a scientific debate - their polemics are geared to ensuring naturalism is uncontested and that the worldview of science is materialism. Since doctrinaire philosophical materialists do not constitute a majority within science, it is very important that the present impasse is broken.

Protracted continental collisions argue for continental plates driven by basal traction
Walter Alvarez
Earth and Planetary Science Letters, Volume 296, Issues 3-4, 1 August 2010, Pages 434-442 | doi 10.1016/j.epsl.2010.05.030

Abstract: In plate tectonic theory, collision between two continents should quickly terminate because of continental buoyancy. If convergence is to continue, it should do so at a new subduction zone where oceanic crust can be consumed. The protracted continental collisions in the Alps, Zagros, and Himalayas, which have continued to deform continental crust since the early or middle Cenozoic, are therefore anomalies in standard plate tectonic theory. It is commonly held that plates are driven by slab pull, but this does not account for the continuing Tethyan collisions where the descending slab has detached from the subducting continent. These protracted continental collisions are better explained by horizontal traction of the mantle on the base of deep continental roots, dragging the northern and southern continents together along a Tethyan axis of mantle convergence. "Continental undertow" thus resolves the collision anomaly in plate tectonics.

See also:

Tyler, D. Does Science promote atheism? ARN Literature Blog (23 July 2007)

It is well known that orb-weaving spiders put droplets of adhesive all over their webs to catch prey. Although there have been many attempts to study the nature of these adhesives, it is only recently that experiment designs have allowed the mechanism of adhesion to be analysed properly. Single adhesive droplets have been probed at varying extension rates.

"Here, by directly probing single adhesive droplets used by spiders, we demonstrate the importance of the mechanics of adhesive in dramatically enhancing adhesion. We show that glue drops function as a viscoelastic material instead of as a viscous material and that the elasticity of the principle adhesive in this system, the glycoproteins, increases adhesion by two orders of magnitude in comparison with capillary forces, thus putting to rest the old notion of the adhesive being viscous."

Lower Cretaceous spider's web. "The advanced structure of this fossilized web, along with the type of prey that the web caught, indicates that spiders have been fishing insects from the air for a very long time." (Credit: American Museum of Natural History, source here)

The glycoproteins are cross-linked (either physically or chemically) enabling forces to be transmitted efficiently. At slow speeds, the pull-off forces are low; but at high speeds, the forces rise dramatically. Thus, when an insect first impacts the web, it is moving fast - and the web adhesive produces its largest gripping force. This allows the spider time to subdue the insect - and by then the adhesive forces have reduced in magnitude so that the spider can remove the insect from the web with relative ease. As in all biomimetic studies, these are coveted properties that we wish to emulate:

"This finding should significantly benefit the development of synthetic adhesives for biomedical, orthopedics and wound-healing applications. The understanding of how spiders use this unique glue will allow scientists to develop reversible adhesives that work in the presence of water," says Dhinojwala.

Lee points out that spider adhesive is a smart material, and that we are only beginning to understand its secrets.

"Man-made glues are mono-functional - their material properties are designed to stick one thing to another, and that's it. But in Nature Communications, Sahni et al. report that the 'glue' droplets that coat spiders' webs are multi-functional. Depending on the rate at which they are extended, the droplets act either as a viscous adhesive or as a rubber-like elastic solid." [. . .]
"But in-depth knowledge of the molecular structure of the glue droplets on spiders' webs is lacking. [. . .] A series of studies investigating the molecular content and supramolecular assembly of glue droplets is therefore required."

Whilst this research is a splendid example of empirical science in action (understanding how the natural world operates), the issue of origins is raised in this paper. An evolutionary framework is adopted, not because the research is dependent on that framework, but because papers that refer to design (especially "well-designed" features) apparently need to affirm non-intelligent causation. So, the first paragraph of the paper begins with this:

"Nature has evolved a myriad of well-designed adhesives that assist in locomotion, self-defence and prey capture. Geckos use micron-sized hairs as dry adhesives for locomotion. Mussels secrete specialized proteins to stick under water. Modern orb-weaving spiders use micron-sized glue droplets laid on a pair of viscoelastic axial silk for catching prey."

The exquisite design apparent in spider silk does not just relate to its remarkable strength, but to its ability to manage water and also, as noted in this blog, to the properties of the applied adhesive drops. In all these cases, the designs are not easy to reproduce. Large amounts of research funds are devoted to mimicking the natural products. It is not a trivial exercise! Even with years of intelligent activity by teams of researchers, problems remain unsolved. No explanation of origins that attributes all this complexity to natural causation has succeeded in convincing anyone who has not already adopted the ideology of evolutionary theory. Add to this the evidence that the first spiders appeared abruptly in the fossil record: the Mesothelae appear in the Carboniferous essentially identical to living forms. Furthermore, although appearing in Mesozoic and Cenozoic deposits, other spider families are represented which are also comparable with modern specimens. The evolutionary ancestors of the whole group is unknown (see here). It is a shame that a paper that marks a significant step forward in understanding the complexity of spider web stickiness should be mixed up with assertions about origins that are so lacking in substance.

Viscoelastic solids explain spider web stickiness
Vasav Sahni, Todd A. Blackledge and Ali Dhinojwala
Nature Communications, 1, No.19, 1-4, (17 May 2010) | doi:10.1038/ncomms1019

Abstract: Modern orb-weaving spiders have evolved well-designed adhesives to capture preys. This adhesive is laid on a pair of axial silk fibres as micron-sized glue droplets that are composed of an aqueous coat of salts surrounding nodules made of glycoproteins. In this study, we measure the adhesive forces required to separate a small microscopic probe after bringing it in contact with a single glue droplet. These forces are highly rate-dependent and are two orders of magnitude higher than the capillary forces. The glycoproteins in the glue droplets behave as a viscoelastic solid and the elasticity is critical in enhancing adhesion caused by specific adhesive ligands. These results have important implications in mimicking bioadhesives.

See also:

Lee, H. Intelligent glue, Nature, 465, 298-299 (19 May 2010) doi:10.1038/465298a

Researchers discover spider webs' true 'sticking power', PhysOrg.com (May 17, 2010)

UA researchers discover true sticking power of spider webs (video)

Conspiracies to suppress, manipulate and distort information undoubtedly occur. Society needs to be vigilant to guard against deception. An increasing number of alleged conspiracies are being covered by the media, all reflecting in some way on the integrity of politicians, or business leaders or the scientific enterprise. Conspiracy theorists are skilled in appealing to emotion, phrasing allegations in a provocative way, and promoting their own reconstructions of events so as to capture the imagination of the public. Ted Goertzel's essay on this theme sounded some alarm bells when it provided four recent examples:

"Conspiracy theorists - some of them scientifically trained - have claimed that the HIV virus is not the cause of AIDS, that global warming is a manipulative hoax and that vaccines and genetically modified foods are unsafe."

(Source here)

The problem I have with this is that these cases are all examples of dissent within science, whatever else may be said about associated conspiracy theories. My purpose here is not to align myself with all these dissenters (although in two of the cases I find myself at variance with the apparent consensus), but to defend the legitimacy of dissent within science. It is vital for the health of science that dissenters have the opportunity to probe, to question and to challenge the theoretical framework of the science relevant to their case, and to test all theories by reference to empirical data. The danger I see in Goertzel's analysis is that legitimate dissent is marginalised and treated as the product of conspiracy theory. The consequence is that science is damaged because reasoned arguments of dissenters are re-categorised as "emotional appeals, unsupported allegations and unverified speculations".

In Goertzel's analysis, conspiracy theorising is a rhetorical device employed for a variety of cultural, political and personal reasons. To develop the thesis, he finds it "useful to think of conspiracy theorizing as a 'meme', a cultural invention that passes from one mind to another and survives, or dies out, through natural selection". The effect of this definition of the issues is to exclude the conspiracy theorising meme from scientific discourse: a form of demarcation.

My concern is that Goertzel's four main examples of contemporary conspiracy theorising are, as a consequence, excluded from discussion in the world of science and relegated to political, economic and sociological forums. The first of these examples is the relationship between the HIV virus and AIDS. In 2008, Duesberg and colleagues published a paper incorporating their dissenting views in the journal Medical Hypotheses. So strong was the hostile reaction to this paper that the Editor, who personally carried the responsibility for reviewing manuscripts, was given notice of dismissal by Elsevier (the publisher of the journal) unless the peer review process followed a more conventional format. This ultimatum was resisted by the Editor and the entire Editorial Board. According to ScienceInsider (May 17th 2010), "Bruce Charlton, the editor of the controversial journal Medical Hypotheses, was fired last week by publisher Elsevier for refusing to overhaul the review procedures at the journal. Now, a majority of the 19-member Editorial Advisory Board seems set to quit as well." The intervention reveals a variety of influences that are alien to scientific discourse. Those opposed to the Duesberg message are not addressing his arguments but are engaged in a power-struggle to prevent dissenting views being published. For Professor Charlton's parting words, go here.

Case two is anthropogenic global warming. At least, in this instance, Goertzel recognises that both sides have been alleging conspiracies!

"In the realm of science, the 'climategate' scandal that has dogged the University of East Anglia's Climatic Research Unit (CRU; Norwich, UK) has seen the word conspiracy thrown about on both sides of the argument. Climate change 'sceptics' have accused Professor Phil Jones of conspiring with his collaborators to manipulate climate data and the scientific literature, while supporters of the CRU have pointed out that the hacking of the e-mails and the selective, pejorative quoting of their content was a conspiracy to discredit the scientific evidence for climate disruption."

It is worth noting that the two groups of scientists interpret the data in different ways and both claim that the other side is involved in conspiracy theorising. At very least, this ought to sound alarm bells in the minds of all who value the health of science: the priority is to promote evaluation of the scientific arguments, not to close ranks with the consensus and to treat the dissenters as pariahs who have betrayed their scientific training by bowing to vested interests. Goertzel sides with those who think that some of the scientists have been over-enthusiastic and have made mistakes, but also that the link between global warming and human activities (of burning fossil fuels) is robust.

"Climate science is heavily dependent on complex statistical models based on limited data, so it is not surprising that models based on different assumptions give differing results. In presenting their data, some scientists were apparently too quick to smooth trends into a 'hockey stick' model that fitted with their advocacy concerns. Several different groups of well-qualified specialists have now been over the data carefully, and the result is a less linear 'hockey stick' with a rise in temperature during a 'medieval warm period' and a drop during a 'little ice age'. But the sharp increase in warming in the twentieth century, which is the main point of the analysis, is still there."

This appraisal is not shared by the dissenters, who point to far deeper and more fundamental issues. The most important of these is, in my opinion, the strategy of using peer review and editorial control to reinforce the "consensus" position. This is highlighted by Andrew Montford (The Times Higher, 25 March 2010), who wrote: "Among the most serious allegations to emerge in the wake of the leaked emails is that CRU scientists tried to "nobble" scientific journals that accepted papers from sceptics. There are suggestions in the emails that as many as four different journals may have had their normal procedures interfered with."
It is not difficult to find people who have been adversely affected. Here is a statement from Dr Sonja Boehmer-Christiansen, who was editor of one of the above-mentioned journals. "My interests are purely academic, professional and political. I am interested in the value and misuse of the peer review process. The negative attitudes of the IPCC/CRU people to my often sceptical journal have harmed it." There have been several formal enquiries that have cleared the relevant climate science leaders of unprofessional conduct, but many of us are mystified by these outcomes. The unethical practices revealed in the emails seem to be so blatant. The clearest and most sensible peer-reviewed comment on the debacle, in my opinion, comes from Stanley Trimble, professor of geography at the University of California at Los Angeles.

"Having said that, I must add that Climategate is, in my view, the greatest science scandal in my lifetime. Beyond any scientific implications are the implications of the behavior of the East Anglia scientists and their correspondents - suppressing information, denigrating those who don't agree with them, trying to deny others access to scientific journals, questioning motives, and conniving to disfellow skeptical colleagues. These are the earmarks of zealotry. While maybe not illegal, they are most certainly unethical. Civilized people, much less scientists, just don't do those things - but then, apparently they do."

In similar vein, comments could be made to show that Goertzel's other major examples (vaccines and genetically modified foods) originate as dissent within science and consequently the issues deserve to be addressed within science. Undoubtedly, all these controversies affect public policy, so it is not surprising that politicians, economists and advocacy groups become involved. The desire for consensus should be regarded as a threat to science, because it inhibits the freedom of scientists to debate issues. Yet, this desire for consensus is where Goertzel leads us:

"Decision-makers and the general public are best served when scientists specializing on an issue can reach a reasonable degree of consensus, making clear the limits to their knowledge. If scientists cannot do this, surely it is too much to expect politicians or journalists to do it. But efforts to define a consensus are vulnerable to attacks by conspiracy theorists that portray them as mechanisms for suppressing dissent and debate."

Goertzel's view of science puts emphasis on its progressive nature. One a trend is established, the presumption is made that the science is closing in on reality. Such thinking leads to skepticism about the possibility of scientific revolutions and to minimizing the importance of these revolutions in the history of science.

"Efforts to reach consensus on important questions have been discouraged by the influence of philosophers of science who emphasize conflicting research programmes, paradigm shifts and scientific revolutions. While these events do occur in the history of science, they are exceptional. Most sciences, most of the time, progress with an orderly, gradual accumulation of knowledge that is recognized and accepted by specialists in the field. Opposition rooted in religious or ideological concerns is acceptable as part of the democratic political process, but it need not prevent scientists from reaching a consensus when one is justified."

The problem I find with this is that consensus should not be a goal, but it may be a spin-off resulting from the application of the scientific method. It may be desirable for making public policy, but that should not dictate the way scientists operate. Those of us who warm to Thomas Kuhn's analysis of 'normal science' and 'scientific revolutions' have no problem with progression within a paradigm, but we infer that this points to internal consistency rather than realism.

The design paradigm gets a brief mention in Goertzel's paper - in the context of the "advocacy meme" (there are two sides to every question and each side is entitled to equal time to present its case). "George W. Bush famously suggested that students be taught both evolution and "intelligent design" theories so that they could judge which had the most convincing argument." Significantly, Goertzel refers to the sound-bite of a political leader rather than a scientist. But here too, the issue should not be reduced to the conspiracy theory format. There are scientific issues, as Dr Stephen Meyer has shown, concluding that there are "pedagogical, legal and scientific case for exposing students to the scientific controversies that exist about the key claims of neo-darwinism, including the claim that the selection-mutation mechanism can fully account for the appearance of design in biological systems." These controversies are discussed in the textbook Explore Evolution (2009).

My greatest concern about Goertzel's paper is that the scientists representing the consensus position are viewed through positivist glasses. Consequently, they pursue objective information and analysis; they don't have emotional attachments to their theories; they don't make unsupported allegations about those who might differ from them; they do not indulge in unverified speculations. These are cardboard scientists who do not exist in the real world. Sociologists of science ought to know better. What we need in all these contested areas is a greater willingness to engage with those who differ from us; an openness to challenging our own favoured ideas; and a willingness to follow the evidence wherever it leads.

Conspiracy theories in science
Ted Goertzel
EMBO reports, 11(7), July 2010, 493-499 | doi:10.1038/embor.2010.84

First para: Conspiracy theories are easy to propagate and difficult to refute. Fortunately, until a decade or so ago, few serious conspiracy theories haunted the natural sciences. More recently, however, conspiracy theories have begun to gain ground and, in some cases, have struck a chord with a public already mistrustful of science and government. Conspiracy theorists - some of them scientifically trained - have claimed that the HIV virus is not the cause of AIDS, that global warming is a manipulative hoax and that vaccines and genetically modified foods are unsafe. These claims have already caused serious consequences: misguided public health policies, resistance to energy conservation and alternative energy, and dropping vaccination rates.

Climategate: If The Science Is Solid, Why Stoop?
Stanley W. Trimble
Academic Questions, (March 2010) 23(1): 54-56 | doi 10.1007/s12129-009-9149-z

Preface: I must preface my remarks by saying that I believe that there has indeed been climate warming over the past few decades and I believe that human action may be one of the causes. While Climategate may bring into greater question some of the work underlying climate warming, it decidedly does not disprove it.

See also:

Tyler, D. Scientific Consensus is sleep inducing, ARN literature Blog (9 June 2010)

Our knowledge of the fossil record has changed immensely since 1859, when Darwin felt obliged to explain why his hypothesis of gradualism was not confirmed by the study of fossil successions. His argument was, as is well known, that the fossil record exhibits extreme imperfection. The abrupt appearance of macrofossils at the base of the Cambrian was recognized and Darwin deduced that the evolutionary origins of those animals must have extended well back into the Precambrian.

"One-and-a-half centuries of subsequent research have revealed a vast microscopic fossil record of unicellular protists and bacteria extending, some would argue, as far back as there are sedimentary rocks from which they could be recovered. But although fossils of millimetre- to metre-scale multicellular organisms characterize the 90 million years of the Ediacaran period that precedes the Cambrian, pre-Ediacaran macroscopic fossils are exceedingly rare."

The newly reported fossils from Gabon were laid down in shales (Source here)

Over the years, various attempts have been made to vindicate Darwin's approach. The Ediacaran fauna shows that soft-bodied animals were preserved in the Precambrian, even in coarse sandstone beds, suggesting that fossils are not found because they were not there. In any case, there is no gradualist understanding of the Ediacaran fauna or any gradualist connection with the fossils of the "Cambrian Explosion". Prior to this, there is a unicellular fossil record with very few suggestions of macroscopic fossils. The newly reported finds are from sediments dated at 2.1 billion years old. They are interpreted by the researchers "as highly organized and spatially discrete populations of colonial organisms" with growth patterns "commonly associated with multicellular organization". If correct, this makes them the earliest known multicellular life.

"We have these macrofossils turning up in a world that was purely microbial," says Stefan Bengtson, a palaeozoologist at the Swedish Museum of Natural History in Stockholm and a co-author on the report. "That's a big deal because when you finally get big organisms, it changes the way the biosphere works, as they interact with microbes and each other." (Source here)

If confirmed, this discovery are exciting, although it "raises more questions than it answers". We consider below whether Darwin's expectations are met. However, some cautionary comments are appropriate in the interests of promoting multiple working hypotheses. Donoghue and Antcliffe's News & Views article considers the arguments put forward by the research team and declare:

"The null hypothesis, however, has to be that these remains represent bacterial colonies. Future work must determine whether the sterane signature, a hallmark of eukaryotes, is derived from soluble organics generated within the sediments, or whether they migrated into these sediments from younger rock sequences. [. . .] Although the fossils are macroscopic, they do not seem to represent anything other than the basic type of multicellularity, which occurs earlier in time in the form of stromatolites."

We should recognize that some scholars with expertise in this field are skeptical. R. Ford Denison gives several reasons, including: "A consistent size and shape is another criterion for true multicellularity, met by Volvox, for example. The fossils don't look any more consistent in size and shape than one would expect from bacterial colonies." In a Nature News item, Maxmen draws attention to another:

"Calling the Gabon specimens "pseudo-fossils", palaeontologist Adolf Seilacher at Yale University in New Haven, Connecticut, instead interprets them as aggregations of the mineral pyrite that grew in different shapes depending on the changing state of the surrounding sediment. In 1998, Seilacher reported finding a fossil eukaryote 1.1 billion years old. Referring to that find, he says: "I now firmly believe that my own so-called first animals were pseudo-fossils too.""

But let us allow that these putative fossils represent genuine multicellular organisms. Does it support a Darwinian perspective on evolution? Donoghue and Antcliffe think that it does:

"But within the confines of a very patchy global record of Proterozoic and Archaean rocks, which extend from about 3.8 billion years ago to the beginning of the Cambrian, these remains contribute to a fossil record that belies the dated caricature painted in the Origin. It was Darwin's view that absence of organisms in these early intervals of Earth's history would prove his theory of biological evolution wrong. The discovery and continuing elucidation of the Precambrian fossil record has met Darwin's predictions on the extent and structure of evolutionary history."

The "absence of organisms" problem persists for Darwinism, as the abrupt appearance of animal phyla in the Cambrian Period is not preceded by any evidence of gradual transformation. It is preceded by multicellular organisms in the Ediacaran - but largely unrelated to the Cambrian fauna. It is preceded by unicellular life forms, but there is no convincing Darwinian perspective on these (see here and here). The discovery of an isolated early multicellular organism does nothing to support gradualism, because there is no gradual succession of ancestral or descendant forms. The find should be regarded as enigmatic until further insights into context are obtained.

Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago
Abderrazak El Albani, Stefan Bengtson, Donald E. Canfield, Andrey Bekker, Roberto Macchiarelli, Arnaud Mazurier, Emma U. Hammarlund, Philippe Boulvais, Jean-Jacques Dupuy, Claude Fontaine, Franz T. Fursich, Francois Gauthier-Lafaye, Philippe Janvier, Emmanuelle Javaux, Frantz Ossa Ossa, Anne-Catherine Pierson-Wickmann, Armelle Riboulleau, Paul Sardini, Daniel Vachard, Martin Whitehouse & Alain Meunier
Nature, 466, 100-104, (01 July 2010) | doi: 10.1038/nature09166

First para: The evidence for macroscopic life during the Palaeoproterozoic era (2.5-1.6 Gyr ago) is controversial. Except for the nearly 2-Gyr-old coil-shaped fossil Grypania spiralis, which may have been eukaryotic, evidence for morphological and taxonomic biodiversification of macroorganisms only occurs towards the beginning of the Mesoproterozoic era (1.6-1.0 Gyr). Here we report the discovery of centimetre-sized structures from the 2.1-Gyr-old black shales of the Palaeoproterozoic Francevillian B Formation in Gabon, which we interpret as highly organized and spatially discrete populations of colonial organisms. The structures are up to 12 cm in size and have characteristic shapes, with a simple but distinct ground pattern of flexible sheets and, usually, a permeating radial fabric. Geochemical analyses suggest that the sediments were deposited under an oxygenated water column. Carbon and sulphur isotopic data indicate that the structures were distinct biogenic objects, fossilized by pyritization early in the formation of the rock. The growth patterns deduced from the fossil morphologies suggest that the organisms showed cell-to-cell signalling and coordinated responses, as is commonly associated with multicellular organization. The Gabon fossils, occurring after the 2.45-2.32-Gyr increase in atmospheric oxygen concentration10, may be seen as ancient representatives of multicellular life, which expanded so rapidly 1.5 Gyr later, in the Cambrian explosion.

Origins of multicellularity
Philip C. J. Donoghue & Jonathan B. Antcliffe
Nature, 466, 41-42, (01 July 2010) | doi: 10.1038/466041a

Interpreting truly ancient fossils is an especially tricky business. The conclusion that 2.1-billion-year-old structures from Gabon are the remains of large colonial organisms will get palaeobiologists talking.

See also:

Maxmen, A. Ancient macrofossils unearthed in West Africa, Nature News (30 June 2010) | doi:10.1038/news.2010.323