Science Literature

Although it did not appear to hit the popular media, a recent paper on the Earth's earliest non-marine eukaryotes is worthy of note here. Like many discoveries, the researchers were not expecting to find what they did. Conventional wisdom is that the Precambrian land surface was barren, and that the important developments were to be found in the sea. So Torridonian rocks from NW Scotland, having all the marks of non-marine sediments, were not expected to yield much of interest. The story is continued by Cristina Luiggi in The Scientist:

"In 2007, Strother and a colleague came across a dusty museum collection of microfossil slides recovered from an outcrop of the oldest sedimentary rocks in the British Isles: the Torridonian sequence. Sections of these rocks date between 1 to 1.2 billion years, and have preserved sediments that were once part of freshwater lakes formed in the depressions of an ancient land surface. To Strother's amazement, the collection contained what appeared to be fossils of multicellular organisms. "We were finding clusters of cells as well things that looked like little pieces of tissue," he said. This came as a surprise given that multicellular organisms of that time period were believed to exclusively inhabit the oceans."

Artist reconstruction of specimens from the Applecross Formation, Loch Diabaig. (Credit: Oxford University/Martin Brasier, source here)

The find triggered an extensive search using samples gathered from all groups of strata comprising the Torridonian - and evidences of eukaryotes were found at all horizons. This means that from the beginning of the Neoproterozoic era, non-marine eukaryotes have been preserved. The researchers have found complexity, as is shown by the following quote from their paper:

"The Torridonian assemblages contain some striking examples of microfossils that show complexity that goes considerably beyond that of simple leiospheres. Figure 1h illustrates a multicellular sphere from a phosphatic nodule with a clearly differentiated outer wall [. . .] Some of these interior cells retain a dense 'spot', probably the plasmolysed remnants of original cell contents. Figure 2b illustrates a large fusiform vesicle (475 mm wide) with a pitted interior wall structure. Figure 2d shows a dark, heterogeneous central body enclosed within a large cyst with a peripheral asymmetrical structure, which itself appears to consist of several cylindrical cells or membranous outgrowths of the vesicle wall."

They were also impressed by the diversity of what they have documented (possibly 50 species):

"Sample to sample heterogeneity seen throughout the Torridonian clearly indicates a significant degree of biotic diversity, reflecting adaptation to freshwater aquatic and subaerially exposed habitats by earliest Neoproterozoic time. Early eukaryotes were clearly capable of diversifying within non-marine habitats, not just in marine settings as has been generally assumed."

What do these findings mean for our understanding of life on the Precambrian Earth? Dr Charles Wellman, an author of the paper, is quoted by ScienceDaily as saying:

"It is generally considered that life originated in the ocean and that the important developments in the early evolution of life took place in the marine environment: the origin of prokaryotes, eukaryotes, sex and multicellularity. During this time the continents are often considered to have been essentially barren of life -- or at the most with an insignificant microbial biota dominated by cyanobacteria. We have discovered evidence for complex life on land from 1 billion year old deposits from Scotland. This suggests that life on land at this time was more abundant and complex than anticipated. It also opens the intriguing possibility that some of the major events in the early history of life may have taken place on land and not entirely within the marine realm."

We should note that marine organisms are isotonic with seawater: this means the same salt concentration exists inside as well as outside the cell membrane and there are no osmotic pressures. However, fresh-water and land organisms are all hypertonic, which means that the internal salinity exceeds that of the fresh-water outside the cell, and unless there are mechanisms to counter osmosis, the cell will die. In addition, non-marine life may have to face the problem of desiccation. This appears to be a real issue for some of the Torridonian eukaryotes, because some of the samples were obtained from desiccation cracks in the Diabaig Formation at Loch Diabaig (this is of personal interest, having obtained samples of these desiccation cracks some years ago from this same locality). The researchers comment:

"Freshwater habitats are ecologically more variable than marine habitats, providing temporal and physiochemical heterogeneity, including wet-drying cycles and direct atmosphere-organism gas exchange. Such habitat heterogeneity translates directly into increased speciation potential. Some of the microfossils illustrated here must have experienced subaerial exposure because they occur in situ in microbially induced sedimentary structures with desiccation cracks, but the extent to which they lived subaerially cannot be ascertained with certainty."

Speciation potential is fair enough as a concept, but the hard work then starts - to identify viable routes for generating the relevant biological mechanisms and associated information. This is where big questions have to be raised about the viability of mutation and natural selection to deliver significant changes (see here). When confronted by the realities of the changes that are needed, it is very easy for evolutionists to put out what they call a plausible narrative - otherwise known as "Darwinian storytelling".

One of the themes developed in this blog has been an ecological perspective on the fossil record. This suggests that the key issues to grasp when seeking to understand past life relate to ecology and the environment. Here we have another example. In the Neoproterozoic, seawaters were not yet able to support multicellular animals - for these, the Earth had to wait until the Ediacaran (for an advance party) and then the Cambrian (for the explosion of animal life).
Nevertheless, the Neoproterozoic could support some eukaryote species (as well as prokaryotes). And that's what we find, not only in the seas but also on land. The word "surprising" appears alongside this discovery, but this draws its rationale from Darwinian gradualism - but from a design perspective, the Earth was ready for freshwater life.

"We've been thinking about the evolution of life in the Precambrian as primarily happening in the oceans," Strother said, "but 1 billion years ago, fresh water environments were really teeming with life."

Earth's earliest non-marine eukaryotes
Paul K. Strother, Leila Battison, Martin D. Brasier & Charles H. Wellman
Nature, 473, 505-509, (26 May 2011) | doi:10.1038/nature09943

The existence of a terrestrial Precambrian (more than 542 Myr ago) biota has been largely inferred from indirect chemical and geological evidence associated with palaeosols, the weathering of clay minerals and microbially induced sedimentary structures in siliciclastic sediments. Direct evidence of fossils within rocks of non-marine origin in the Precambrian is exceedingly rare. The most widely cited example comprises a single report of morphologically simple mineralized tubes and spheres interpreted as cyanobacteria, obtained from 1,200-Myr-old palaeokarst in Arizona. Organic-walled microfossils were first described from the non-marine Torridonian (1.2-1.0 Gyr ago) sequence of northwest Scotland in 1907. Subsequent studies found few distinctive taxa - a century later, the Torridonian microflora is still being characterized as primarily nondescript "leiospheres". We have comprehensively sampled grey shales and phosphatic nodules throughout the Torridonian sequence. Here we report the recovery of large populations of diverse organic-walled microfossils extracted by acid maceration, complemented by studies using thin sections of phosphatic nodules that yield exceptionally detailed three-dimensional preservation. These assemblages contain multicellular structures, complex-walled cysts, asymmetric organic structures, and dorsiventral, compressed organic thalli, some approaching one millimetre in diameter. They offer direct evidence of eukaryotes living in freshwater aquatic and subaerially exposed habitats during the Proterozoic era. The apparent dominance of eukaryotes in non-marine settings by 1 Gyr ago indicates that eukaryotic evolution on land may have commenced far earlier than previously thought.

See also:

Supplementary information here.

Loch Fossils Show Life Harnessed Sun and Sex Early on, ScienceDaily (14 April 2011)

Luiggi, C. Old open air voyagers, The Scientist (13th April 2011)

The editors-in-chief of Synthese, a leading philosophy journal, published an unusual disclaimer in the print-version of a guest edited special release of the journal. Basically, they apologised that some of the papers in the "Evolution and Its Rivals" issue fell short of the standards of professional discourse that would be expected by readers.

"We believe that vigorous debate is clearly of the essence in intellectual communities, and that even strong disagreements can be an engine of progress. However, tone and prose should follow the usual academic standards of politeness and respect in phrasing. We recognize that these are not consistently met in this particular issue. These standards, especially toward people we deeply disagree with, are a common benefit to us all. We regret any deviation from our usual standards."

Demarcation lines and warfare warfare often go together - but do we need one to define science? (Image source here)

The guest editors took this badly, and a heated discussion has followed (see here and here). One philosopher, Brian Leiter produced a blog post "Synthese Editors Cave in to Pressure from the Intelligent Design Lobby: Philosophers Should Boycott Synthese." The special issue was concerned with intelligent design and creationism, and all the papers were contributed by critics - some outspokenly hostile. The most extreme example of unprofessionalism came from the philosopher Barbara Forrest, whose hatchet-job on another philosopher Francis J. Beckwith, was triggered by his claim that the teaching of intelligent design in public schools is constitutionally permissible. The Synthese Editors-in-Chief have offered Beckwith the opportunity to respond in a future issue of the journal. The Forrest paper has been the subject of comment here and here.

This blog considers another case of bully-boy behaviour masquerading as scholarship - the paper on demarcation by Robert T. Pennock. Those most opposed to intelligent design (ID) and creationism have typically maintained that a clear line can be drawn between science and non-science, and ID and creationism are declared to be outside the boundary of science. In this essay, Pennock choses to talk down to one of his peers in the world of philosophy. An example is as follows:

"When we look empirically at what scientists and science educators themselves say science is, then we see immediately that they all ignore Laudan and clearly operate on the idea that there is a real distinction between science and non-science. Indeed, the evidence for this view is so pervasive that it is hard to see how one can take Laudan's incredible pronouncements as anything but indicating a cavilier [sic] disregard for the balance of evidence and a foolhardy disengagement from what should be the subject matter of philosophy of science. I can here only give an outline of some of some of what Laudan had to ignore in his anti-demarcationist screed."

A bit of background may help those not familiar with the demarcation debates between philosophers of science. Some have argued strongly that science can be distinguished from non-science by a number of criteria (these are the demarcation criteria). Examples of some of these criteria are falsifiability (science involves testing hypotheses to establish whether they are consistent or falsified), and the ability to make predictions (with hypotheses being a form of prediction). After claiming that ID and creationism fail against these criteria, the conclusion is drawn that ID and creationism should be excluded from science and treated as sectarian religion or as political activist movements. However, the giant fly in this ointment is that some other philosophers of science find that all the proposed criteria fail under close scrutiny because disciplines that are widely regarded as legitimate science would also have to be excluded. These philosophers regard the demarcation issue as dead. Pennock defends the demarcation approach and Laudan has championed the other side.

Before looking at these issues more closely, it is worth noting that Pennock appeals repeatedly to the scientific consensus. This is apparent in the quotation given above and it is pervasive in his paper. This strikes me as surprising for a philosopher to be so impressed by the majority view - philosophers are supposed to reach conclusions by the use of reason, without giving weight to how many people support a particular position. Here is another example, this time relating to methodological naturalism (MN) - the view that the methodology of science should assume that all causes are natural (i.e. excluding intelligent causation):

"there is good reason to think that MN is accepted by a large majority of philosophers of science and is probably as close to a settled consensus as is possible in our profession. In any case, as will be discussed in detail in the next section, there is excellent evidence that it is all-but-universally accepted as a tacit ground rule of science among scientists, which is the more relevant standard."

The controversy surrounding the disclaimer was the subject of a philosophy blog here, inviting comments. One of the respondents was Larry Laudan, who has long arguing that the 'demarcation problem' cannot be solved. Laudan refrains from commenting on whether the editors were pressurised to issue the disclaimer, but declares that their statement "was not only in order but essential as a matter of professional ethics." He goes on to identify himself as the target of Pennock's vitriol:

"I will limit my comments to a single paper by Robert Pennock from the issue in question. In the course of some twenty pages, he alleges that the work of a fellow philosopher is "almost willfully naive and misguided", that it "can only be described as histrionic and ill-considered" and that it "continue[s] to muddy the waters to the detriment of both science and philosophy of science". He goes on to endorse the proposal that the philosopher in question should be excluded from 'the conversation of mankind' because said author "ha[s] lost touch with reality in a profound and perverse way". Those of you who have read Pennock's paper will know that I am not a wholly disinterested party here, since all his barbs are directed specifically at yours truly. But I think I can lay aside self interest long enough to say that discourse of this sort has no legitimate place in any serious journal of philosophy (most especially the suggestion that those who disagree with Pennock should be excluded from 'the conversation of mankind')."

We need to recognise that Laudan is writing as a philosopher of science, and the stance he takes does not imply he is an ID supporter. Nevertheless, he presents demarcation arguments as a slovenly contrivance that leads to a cardboard front for the enterprise of science. He offended many of his colleagues by commenting negatively on the testimony of Michael Ruse at the 1981-1982 McLean v. Arkansas legal case:

"The victory in the Arkansas case was hollow, for it was achieved only at the expense of perpetuating and canonizing a false stereotype of what science is and how it works. If it goes unchallenged by the scientific community, it will raise grave doubts about that community's intellectual integrity."

This blog does not attempt to address Pennock's 30-page defense of demarcation. However, it is worth pointing out that methodological naturalism and demarcation are inextricably linked in the minds of Pennock and many others. If science is defined as a discipline that considers only natural explanations of phenomena, then ID and creationism are excluded from science by definition (as are archaeology and forensic science!). Here is Pennock again, commenting on a (2000) statement by the National Science Teachers Association on the nature of science:

"Although no single universal step-by-step scientific method captures the complexity of doing science, a number of shared values and perspectives characterize a scientific approach to understanding nature. Among these are a demand for naturalistic explanations supported by empirical evidence that are, at least in principle, testable against the natural world. Other shared elements include observations, rational argument, inference, skepticism, peer review and replicability of work. [. . .] Science, by definition, is limited to naturalistic methods and explanations and, as such, is precluded from using supernatural elements in the production of scientific knowledge."
Pennock comments:
"In another statement on the teaching of evolution, NSTA explicitly rejects creation science and ID on the grounds that they are not science for just such reasons. One can find dozens of similar statements from both scientific and science education organizations that in more or less direct ways articulate a presumption of natural regularity and the requirement that science appeal only to naturalistic explanations."

The absurdity of this position is that this mutant version of science is methodologically incapable of detecting intelligent design even if it were "in your face" design. This is the ultimate circular argument, carrying no more authority than a novel. If there is to be any meaningful discourse about design in nature, we have to have tools and methodologies for detecting design - and that is what ID has offered as a way forward.

Can't philosophers tell the difference between science and religion?: Demarcation revisited
Robert T. Pennock
Synthese, Volume 178, Number 2, 177-206 | DOI: 10.1007/s11229-009-9547-3

Abstract: In the 2005 Kitzmiller v Dover Area School Board case, a federal district court ruled that Intelligent Design creationism was not science, but a disguised religious view and that teaching it in public schools is unconstitutional. But creationists contend that it is illegitimate to distinguish science and religion, citing philosophers Quinn and especially Laudan, who had criticized a similar ruling in the 1981 McLean v. Arkansas creation-science case on the grounds that no necessary and sufficient demarcation criterion was possible and that demarcation was a dead pseudo-problem. This article discusses problems with those conclusions and their application to the quite different reasoning between these two cases. Laudan focused too narrowly on the problem of demarcation as Popper defined it. Distinguishing science from religion was and remains an important conceptual issue with significant practical import, and philosophers who say there is no difference have lost touch with reality in a profound and perverse way. The Kitzmiller case did not rely on a strict demarcation criterion, but appealed only to a "ballpark" demarcation that identifies methodological naturalism (MN) as a "ground rule" of science. MN is shown to be a distinguishing feature of science both in explicit statements from scientific organizations and in actual practice. There is good reason to think that MN is shared as a tacit assumption among philosophers who emphasize other demarcation criteria and even by Laudan himself.

See also:

Luskin, C. Synthese Opposed the Disrespectful Methods of Intelligent Design Critics, Evolution News & Views (May 20, 2011)

It has been recognised for some time that the uniformitarianism of Charles Lyell has hindered the development of geological science. It is perhaps less widely known that Charles Darwin perceived himself initially as a geologist and he drew heavily on Lyell's uniformitarian agenda (for an example, go here). Later, as Darwin's focus moved to biology, he retained his commitment to a uniformitarian methodology: evolutionary gradualism was Darwin's attempt to apply uniformitarianism to biology. (For an example of it leading him astray in understanding inheritance, go here). Scholarly criticism of gradualism, however, has been muted because alternatives to Neo-Darwinism lack maturity and there are many hypotheses that await testing. Notwithstanding this, the data derived from a study of fossils has consistently pointed to discontinuity rather than gradualism.

"The ubiquity of morphological discontinuities between clades of organisms has troubled evolutionary biologists since Cuvier and Darwin and remains one of most important questions in evolutionary biology. Why is it that the distribution of morphologies is clumpy at virtually all scales? Although both Darwin and the proponents of the Modern Synthesis expected an 'insensible' gradation of form from one species to the next, this is only sometimes found among extant species (for example, among cryptic species) and is rare in the fossil record."

The pervasive pattern of natural history: disparity precedes diversity (source here)

Despite these problems, many Darwinists have found ways of turning evidence against their theory into something they can be positive about. Notably, they portray the fossil record as compelling evidence that evolution has occurred. Hard-line Darwinists explain morphological disparity by the non-preservation of intermediate forms, allowing them to insist that macroevolution is achieved by extrapolating microevolution. There are a growing number of scholars who recognise the need to develop theory beyond the Modern Synthesis and two approaches are summarised by Erwin thus:

"a hierarchical view of macroevolution where species sorting or selection drives evolutionary trends (although it is not clear how this produces a non-uniform distribution of morphologies); and various formalist or structuralist schools where major evolutionary transitions reflect structural or physical requirements, with selection entering only as a secondary sorting mechanism. Generally absent from each of these approaches is consideration of the possibility that the nature of the evolutionary process, as distinct from the organisms on which evolution acts, has itself evolved over time."

The "Cambrian Explosion" refers to the abrupt appearance of animal phyla and classes in the fossil record. It has been much discussed by both critics and defenders of Darwinism. Apart from pleading the impoverishment of the fossil record, the defenders have sought to 'spread out' the Explosion, to make it appear that gradualism can still be discerned. An example of this approach was blogged here, where I noted that critics have never insised on an instantaneous explosion, but have merely drawn attention to the numerous characteristics of the Explosion that are inconsistent with Darwinism. Stimulated by the iconoclastic approach of Stephen Jay Gould, the critics have shown themselves to be the true empiricists.

"These studies quantitatively substantiated Gould's intuitive conclusion: morphologies really are unevenly distributed at the origin of a clade. In the majority of cases studied, morphologic disparity greatly exceeds taxonomic diversity in the early history of a clade. This result could only be the result of sampling artifacts if one were to posit that unusual morphologies were more likely to be preserved and recovered than morphologies similar to one another, which is hard to credit. Such studies have demonstrated that the apparent gaps between morphologies are not simply due to extinction of once-intermediate forms."

In an important contribution to this debate, Douglas Erwin revisits the task of analysing data relevant to the first appearance of phyla and classes.

"Here I explore growing evidence that a significant factor in the clumpy nature of morphology is systematic, time-inhomogeneous patterns in types of variation upon which natural selection and other evolutionary processes could act. I present a new compilation of the first occurrences of marine invertebrate phyla, classes and equivalent stem groups during the Ediacaran, Cambrian and Ordovician, focusing on the Ediacaran-Cambrian (579-490 Ma) diversification of animals."

The summary of results for phyla is as follows. The pattern reinforces earlier research that concluded the Explosion is not an artefact of sampling. Much the same finding applies to the appearance of classes. These data are presented in Figures 1 and 2 in the paper.

"Ediacaran originations are relatively few, reflecting the uncertainties about the phylogenetic placement of most Ediacaran fossils. A major pulse of origination is evident in Cambrian Stage 1, largely of small skeletonized fossils known as the 'small shelly fossils', followed by the first appearances of many clades in Cambrian Stage 3, corresponding to the exquisite soft-bodied preservation of the Chengjiang biota in southern China. A later, smaller pulse is associated with first appearances in the Burgess Shale fauna of British Columbia, Canada. The only later occurrence of a durably skeletonized phylum is the Bryozoa in Cambrian stage 9. Twelve phyla are known only from the Recent and four phyla first occur in the fossil record after the late Cambrian: one each in the Carboniferous, Jurassic, Cretaceous and Eocene."

Having documented a non-uniformitarian pattern in the empirical data, Erwin turns to analysis and interpretation. He points to work on developmental gene regulatory networks (GRNs), termed kernels, that appear to be highly conserved and "remarkably refractory to subsequent evolutionary change" (previously discussed here). This research has concluded that developmental GRNs formed during the Ediacaran-Cambrian and that their stability corresponds to both the early disparity of the phyla and classes and also their subsequent stasis. This is why uniformitarianism fails as an explanatory framework:

"the establishment of these kernels early in the history of metazoan evolution suggests a temporal change in the type of developmental variation exposed to selection and drift, indicating that aspects of evolutionary change are not uniformitarian."

Erwin's paper helps to structure debate about these important issues. Questions about the origin of phyla and classes can now be represented in terms of the origin of biological information, notably developmental GRNs. Erwin's study shows that gradualistic, incremental approaches to the origin of biological information are in tension with empirical data. This is where debate, if it is to be meaningful, must be focussed.

"The pattern of origination of metazoan phyla and classes is highly non-uniform through the Phanerozoic, with an overwhelming bias towards the Cambrian and Ordovician. In the past non-paleontologists have attempted to rescue uniformitarian explanations by 'explaining away' this empirical pattern as a result of various biases. Both taxic and quantitative morphometric approaches have established that the pattern is accurate reflection of the appearance of morphological novelties. By combining this information on the pattern of morphologic evolution with mechanistic information from comparative studies of modern developmental GRNs, a new, non-uniformitarian view of evolution emerges. From this perspective, the growth of developmental networks has progressively structured the nature of accessible developmental innovations overtime."

There is a 'standard' explanation of the origin of biological information that has been developed by Darwinists (but not by Darwin - who was more interested in diversification than complexity increases). An example of this is given as an addendum - if Darwinists could take this seriously, it would help avoid the distractions of finch beaks and industrial melanism! Erwin's study shows that the Darwinian paradigm, whether or not it can explain the origin of information, is irrelevant to the origin of phyla and classes. We need a debate that takes biological information seriously, including its non-uniformitarian pattern. Causation can be found in Law, Chance and Design, but neither Law nor Chance can deliver complex specified information (here and here). This is why a debate that does not exclude design considerations on ideological grounds is long overdue.

Evolutionary uniformitarianism
Douglas H. Erwin
Developmental Biology, In Press, Available online 27 January 2011

Abstract: I present a new compilation of the distribution of the temporal distribution of new morphologies of marine invertebrates associated with the Ediacaran-Cambrian (578-510 Ma) diversification of Metazoa. Combining this data with previous work on the hierarchical structure of gene regulatory networks, I argue that the distribution of morphologies may be, in part, a record of the time-asymmetric generation of variation. Evolution has been implicitly viewed as a uniformitarian process where the rates may vary but the underlying processes, including the types of variation, are essentially invariant through time. Recent studies demonstrate that this uniformitarian assumption is false, suggesting that the types of variation may vary through time.

Addendum: On the origin of complexity by natural selection
The text below is taken from: Arthur, W. Creatures of accident, New York: Hill and Wang, 2006, pages 118-9.

Like so much about evolution, the production of complexity by natural selection is an accident, or, if you prefer, a by-product. Selection is never trying to achieve anything - it just happens. Because of the nature of the selective process, it inevitably produces adaptation. That is, it causes organisms to have forms and functions that are appropriate to their environment. It does not optimize such forms or functions; rather, it makes the best of a bad job in that it increases the frequency of fitter variants and decreases the frequency of less fit ones. [. . .]
Most selection, most of the time, is probably of this general kind: making limbs more appropriate to the nature of the environment; making beaks more appropriate to the nature of the food supply; and so on. We might call these changes complexity-neutral. But in some small proportion of cases, the thing that is fitter is also more or less complex than the thing it replaces. These, especially the "mores", are the cases on which we must focus our attention.

When first reported, this hominin was given the name Zinjanthropus boisei. He was considered to be a human ancestor and was portrayed as an upright hairy apeman. Later, he was renamed Australopithecus boisei, but then was moved to a separate genus, receiving the name Paranthropus boisei. He still appears in some presentations of human ancestry. What makes him memorable are his magnificent teeth:

"For decades, scientists thought that the large, heavy teeth the primates had were used in cracking open hard foods such as nuts. The common name for Paranthropus was "Nutcracker Man" for this very reason."

This photo of casts of two palates demonstrates the large size of the teeth of Paranthropus boisei (left) known as Nutcracker Man. Much smaller teeth from a human skull are shown on the right. (Credit: University of Arkansas, Melissa Lutz Blouin, source here)

Three years ago, this blog commented on a microwear texture analysis of the molars of seven specimens of P. boisei. The teeth had light wear, suggesting that none of the individuals ate extremely hard or tough foods. In other words, they did not eat nuts! The researchers suggested that the wear pattern was more consistent with modern-day fruit-eating animals.

More recent work has reached a surprising conclusion. P. boisei did not eat fruit but had a diet majoring on grass! This has been discovered by an analysis of carbon-isotope ratios.

"Carbon isotope ratios in tooth enamel can reveal whether ancient animals ate plants that used what is called C3 photosynthesis - trees (and the leaves, nuts and fruits they produce), shrubs, cool-season grasses, herbs and forbs - or plants such as warm-season or tropical grasses and sedges that use what is known as C4 photosynthesis. [. . .] The study found that not only did the Nutcracker Man Paranthropus boisei not eat nuts or other C3 plant products, but dined more heavily on C4 plants like grasses than any other early human, human ancestor or human relative studied to date. Only an extinct species of grass-eating baboon had a diet so dominated by C4 plants. Carbon isotopes showed the 22 individuals had diets averaging 77 percent C4 plants such as grasses, ranging from a low of 61 percent to a high of 91 percent. That's statistically indistinguishable from grass diets of grazing animals that lived at the same time: the ancestors of zebras, pigs and warthogs, and hippos, Cerling says."

How are the enormous teeth to be explained? The researchers have suggested that the high degree of wear observed comes from frequent chewing on foods containing small hard particles - which are, of course, found in C4 grasses. These are known as phytoliths. Although this has not featured in the analysis, this is in tension with the thought that P. boisei was an upright hominin. Grass eaters need to get down to eat - and herbivores generally consume large quantities of food each day. It is significant that the only known primate with a comparable diet was an extinct species of grass-eating baboon.

Furthermore, this discovery "upsets conventional wisdom about early humanity's diet". P. boisei is likely to be a catalyst for fresh thinking about the Australopithecenes - from whom it is considered to have evolved. What interpretation should be placed on the dental features of Australopithecenes?

"Specifically, scientists have believed human ancestors in the genus Australopithecus - which gave rise to now-extinct Paranthropus and to Homo or early humans - also had head and tooth features suggesting they ate hard objects like nuts. Cerling says carbon isotope ratios in australopiths' teeth now should be studied, since the Paranthropus findings bring in to question interpretations that are made without isotopic information on diets."
And from the paper:
"The similarity in dental microwear fabrics among the eastern African australopiths, all of which lack any evidence for hard-object food consumption, is consistent with the notion that their craniodental morphology could reflect "repetitive loading" rather than hard-object consumption."

This research provides another angle on the problems reviewed by Bernard Wood & Terry Harrison (blogged here). It is true that "shared morphology need not mean shared history" but it is also true that shared morphology need not mean shared functionality. Nutcracker Man is a notable example of how morphology was wrongly interpreted for decades and only recently overturned. The problem with "conventional wisdom" is that it has been led by a dogma about the nature of evolutionary transformation from ape-like ancestor to humanity and it is long overdue that this "wisdom" be subjected to some systematic and rational critical scrutiny.

Maybe it will help if this particular fossil hominin gets a new popular name. It was not a nutcracker nor was it a man! It was a specialised (derived) ape that fed primarily on grass and is now extinct. It has nothing to do with human ancestry. Any thoughts on a suitable popular name?

Diet of Paranthropus boisei in the early Pleistocene of East Africa
Thure E. Cerling, Emma Mbua, Francis M. Kirera, Fredrick Kyalo Manthi, Frederick E. Grine, Meave G. Leakey, Matt Sponheimere, and Kevin T. Uno
Proceedings of the National Academy of Sciences, Published online before print May 2, 2011 | doi: 10.1073/pnas.1104627108

Abstract: The East African hominin Paranthropus boisei was characterized by a suite of craniodental features that have been widely interpreted as adaptations to a diet that consisted of hard objects that required powerful peak masticatory loads. These morphological adaptations represent the culmination of an evolutionary trend that began in earlier taxa such as Australopithecus afarensis, and presumably facilitated utilization of open habitats in the Plio-Pleistocene. Here, we use stable isotopes to show that P. boisei had a diet that was dominated by C4 biomass such as grasses or sedges. Its diet included more C4 biomass than any other hominin studied to date, including its congener Paranthropus robustus from South Africa. These results, coupled with recent evidence from dental microwear, may indicate that the remarkable craniodental morphology of this taxon represents an adaptation for processing large quantities of low-quality vegetation rather than hard objects.

See also:

No Nuts for 'Nutcracker Man': Early Human Relative Apparently Chewed Grass Instead, ScienceDaily (May 3, 2011)