Science Literature

We have been told for years that evolutionary biology is pure science and has no religious implications. Theistic evolutionists emphasise the concept of complementarity, pointing out that evolutionary theory seeks to explain how? questions whereas theism is concerned with why? questions. There appear to be many non-theists, including most organisations representing scientists, who say something very similar. These people have adopted the NOMA approach popularised by Stephen Jay Gould. For more on this, go here. However, you do not have to read far in the intelligent design literature (or in the creationist literature) to realise that this approach is controversial. These sources claim that all science has metaphysical presuppositions that are of a religious nature. There is a consistent message coming through - whereas science was first nurtured by scholars with Christian presuppositions, the situation has significantly changed. Since the Enlightenment, science has come to be dominated by the philosophy of naturalism. Happily, some opinion-formers also recognise the validity of this analysis: John Gray has some penetrating comments on this and an excerpt is below.

"As we know it, the secular world-view is simply the Christian take on the world with God left out. Liberal humanism is the contemporary version of an eccentric 19th-century cult - less colourful than its positivist precursor, no doubt, but just as clearly modelled on Christianity. Religious thinkers grasp this and look forward to a post-secular age. Befogged missionaries for a dull Victorian heresy, secular thinkers remain stuck in the past."

Some evolutionists with the mantra "no design, no purpose, no evil and no good, nothing but blind pitiless indifference" find "existential comfort" in rejecting intelligent design. (source here)

The debates about origins have been engineered to present advocates of design as religiously motivated and evolutionary biologists as the champions of facts and evidence. A recent paper authored by psychologists adopts this contrived delineation of the debate as self-evident. Here is the way they introduce the paper:

"Despite overwhelming evidence for Darwin's theory of evolution (ET) and scientific consensus that intelligent design theory (IDT) is inherently unscientific, IDT has received considerable support from the general public, educators, and elected officials. Many schools include IDT in science curricula; 25% of U.S. high-school biology teachers devote at least some class time to the topic, and nearly half of those view IDT as a "valid scientific alternative to Darwinian explanations for the origin of species" [for more on these stats, go here]. Although a Dover, PA, court ruled in 2005 that schools could not include IDT in Pennsylvania science curricula, the debate is far from over."

Since the researchers deduce that the arguments for design can have nothing to do with genuine science, they have sought psychological reasons for the widespread adoption of ID perspectives. This is how they present their hypothesis:

"In the present research, we examined whether implicit concerns stemming from individuals' awareness of their own mortality might be a cause of the widespread support for IDT and corresponding skepticism of ET seen among a wide range of individuals in North America. We tested the hypothesis that heightened mortality awareness would lead individuals to embrace IDT and reject ET; in other words, that shifting one's opinion on these theories is a "terror management" strategy - stimulated by the basic need to maintain psychological security."

So, they constructed a series of experiments that were designed to remind participants of their own mortality, inducing "mortality salience" (MS). Then, the subjects were presented with a passage authored by Richard Dawkins arguing for ET and/or a compilation of comments arguing for IDT linked to the name of Michael Behe. Consequently, an assessment was made of participant views toward the author of each passage and the corresponding theory.

"The researchers carried out five studies with 1,674 U.S. and Canadian participants of different ages and a broad range of educational, socioeconomic and religious backgrounds.
In each study, participants were asked to imagine their own death and write about their subsequent thoughts and feelings, or they were assigned to a control condition: imagining dental pain and writing about that.
The participants were then asked to read two similarly styled, 174-word excerpts from the writings of Behe and Dawkins, which make no mention of religion or belief, but describe the scientific and empirical support for their respective positions.
After going through these steps, participants who imagined their own death showed greater support for intelligent design and greater liking for Behe, or a rejection of evolution theory coupled with disliking for Dawkins, compared to participants in the control condition."

There is much more to the paper than can be captured with a few brief quotations. However, we need to note the conclusions:

From the paper: "In sum, although religious ideology plays a large role in public support for IDT and antagonism toward ET, these attitudes, held by both religious and non-religious individuals, can be partly explained by IDT's potential for assuaging existential anxiety, and ET's apparent lack of an existentially compelling solution to life's origins."
From Science Daily: "Our results suggest that when confronted with existential concerns, people respond by searching for a sense of meaning and purpose in life," says Tracy. "For many, it appears that evolutionary theory doesn't offer enough of a compelling answer to deal with these big questions."

Given their acceptance of "overwhelming evidence" for evolutionary theory, the psychologists go on to consider ways of overcoming the psychological barriers to acceptance of ET. Since this will probably be the focus of wider discussion, this blog points to other implications of the research. Remember that ID scholars are developing scientific responses to the claims of naturalistic science that all phenomena can be explained by a combination of Law and Chance. These scholars are not convinced by the arguments for ET and, in many cases, claim that numerous aspects of ET have already been falsified. What, then, explains the intransigence of evolutionists and their failure to follow through the scientific method they claim to espouse? Why is it that there are so many vocal atheists championing ET? Is there a link between atheism and ET? Returning to John Gray for a moment, does this cast light on his opening comment?

"Religion is a natural human impulse, which our society tries to repress just as the Victorians did sex. That is why atheists are so rancorous and intolerant."

There is great potential for psychologists to turn their telescopes on vocal evolutionists. What made them become vocal? Where do they position themselves in the spectrum of religious views? (Research along these lines will regard atheism as a religious position). Do they use evolutionary science to support their worldview? The reported research confirms that these questions are worth asking, for the authors find that "rejecting IDT can be a source of existential comfort for a limited population of individuals". How might ET advocates react to these statements by Dawkins?

"[A]lthough atheism might have been logically tenable before Darwin, Darwin made it possible to be an intellectually fulfilled atheist." (The Blind Watchmaker (1986), page 6)

"Religion teaches the dangerous nonsense that death is not the end." (Religion's Misguided Missiles, September 15, 2001)

"The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil and no good, nothing but blind pitiless indifference." (River Out of Eden: A Darwinian View of Life, 1995)

If it is true that "evolutionary theory doesn't offer enough of a compelling answer to deal with these big questions", then what might be the reactions of ET's advocates? The answer appears to be that they will dress up their "no design, no purpose, no evil and no good, nothing but blind pitiless indifference" in rather more attractive attire. They will quote more frequently the concluding words of Charles Darwin's magnum opus (but not from the 6th edition!):

"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

We have a growing number of atheistic ET's talking about wonder, mystery and awe at the amazing universe we inhabit. Richard Dawkins set the tone with Unweaving the Rainbow and in various attempts to influence the public understanding of science (see here). Many popularisers of science are following this lead. In the UK we have Professor Brian Cox presenting several series of programmes for the BBC, all characterised by talk of wonder and the thrill of understanding how the universe works. Answers to ultimate questions are hinted at, but take away the hype and we are left with scientism covered by a veneer of existentialism (i.e. we choose to find personal meaning in understanding the science). The psychologists should have plenty of material to work with - but will they apply their skills to deconstruct establishment figures?

Death and Science: The Existential Underpinnings of Belief in Intelligent Design and Discomfort with Evolution
Jessica L. Tracy, Joshua Hart, Jason P. Martens.
PLoS ONE, 2011, 6(3): e17349 | DOI: 10.1371/journal.pone.0017349

Abstract: The present research examined the psychological motives underlying widespread support for intelligent design theory (IDT), a purportedly scientific theory that lacks any scientific evidence; and antagonism toward evolutionary theory (ET), a theory supported by a large body of scientific evidence. We tested whether these attitudes are influenced by IDT's provision of an explanation of life's origins that better addresses existential concerns than ET. In four studies, existential threat (induced via reminders of participants' own mortality) increased acceptance of IDT and/or rejection of ET, regardless of participants' religion, religiosity, educational background, or preexisting attitude toward evolution. Effects were reversed by teaching participants that naturalism can be a source of existential meaning (Study 4), and among natural-science students for whom ET may already provide existential meaning (Study 5). These reversals suggest that the effect of heightened mortality awareness on attitudes toward ET and IDT is due to a desire to find greater meaning and purpose in science when existential threats are activated.

See also:

Death Anxiety Prompts People to Believe in Intelligent Design, Reject Evolution, Study Suggests, ScienceDaily (March 30, 2011)

Predation in the Early Cambrian is demonstrated by the occurrence of borings or drill holes in shelly fauna. Confirmatory evidence has been adduced from gut content analyses, although these evidences could also be attributed to scavenging. However, predation involving shell breakage or crushing has been documented previously only from the late Ordovician. This situation has changed with the published research on Lower Cambrian lingulate brachiopods.

"Here we present the first report of repaired damage to linguliform brachiopod shells caused by durophagous shell-crushing, which is exquisitely recorded from exceptionally preserved specimens in the early Cambrian Wulongqing Formation (Guanshan fauna), Kunming, China. The healed fractures on specimens with preserved thin pedicles unambiguously suggest failed predation attempts. Although they cannot be linked to any specific predators, this record shows that early Cambrian brachiopods experienced predation pressure by unspecified durophagous predators, probably anomalocariids."

Slab containing fossils of Diandongia pista (Source here)

The organism being studied is Diandongia pista, one of the most common species of its type in the Lower Cambrian of South China. It was first studied as a member of the Chengjiang fauna (which is assigned to Stage 3 of the Lower Cambrian). A total of 1150 specimens have been collected for research purposes, none of which have been damaged by predation. The newly reported research is based on a study of fossils of Diandongia pista from the overlying Guanshan fauna (assigned to Stage 4 of the Lower Cambrian). 273 specimens have been collected, 13 of which have non-lethal predatory shell damage and subsequent shell repair. The hypothesis that these features do not signify predation has been examined and rejected.

"However, the possibility of non-predatory causes can be directly rejected with certainty in the specimens described here; the shell damages illustrated from Diandongia cannot have been formed by marginal abrasion of the shell, and the damaged areas are not restricted to anterolateral marginal edge of shell. Evidently, the healed injuries are steeply U or V-shaped, cutting vertically across multiple concentric growth lines, contradicting to the proposed marginal gashes."

These evidences show that the earliest-known record of repaired predatory attack on brachiopods can be assigned to Stage 3 of the Lower Cambrian. The authors infer that predation levels were comparatively very low in the earliest phases of Cambrian brachiopods. Adaptive changes associated with predation are suggested to increase with time, but it is only in the Great Ordovician Biodiversification that it becomes important.

"[T]he emergence and subsequent diversification of smashing/crushing attacks throughout the Cambrian may be the precursor to an Early Palaeozoic marine revolution. Such marine revolutions, attributed to durophage radiations, have been recognized in the Early Cretaceous, and in the Middle Devonian. By the Early Ordovician, brachiopod communities were very different from their Late Cambrian counterparts, and increasing predation pressure from durophages may have been a contributing factor to the proliferation of calcitic-shelled brachiopods in the Ordovician, and possibly to the subsequent infaunal habit of some linguliform taxa, as phosphatic shells were likely insufficient to protect against attacks."

Whilst agreeing with this conclusion of the authors, a design perspective does allow some additional conclusions to be reached. Three of these are outlined below.

1. Drivers of change in the Lower Cambrian. This point is concerned with the Cambrian Explosion and possible drivers of diversification. Darwinian concepts of the struggle for survival have featured strongly in attempts to explain the Cambrian Explosion. However, although predator-prey roles are to be found, the evidence linking these with adaptive change is lacking. Last December, an alternative ecological framework for interpreting this part of the fossil record was discussed (go here for the 4th in the series). The authors introduce their paper by pointing out the importance of this issue in the minds of evolutionary biologists, but then they go on to show evidence that for shell-crushing predation, this selection force was non-existent before Stage 4 of the Lower Cambrian. Some re-evaluation of drivers affecting the Cambrian Explosion is therefore needed.

"Predation has been considered as one of the driving and selective forces in evolution, and thus plays an important macroevolutionary role in marine environments. Coevolution between organisms and their predators had led to an intensification of the struggle for existence and increased complexity of organisms during the Cambrian explosion interval."

2. Evidence of repair mechanisms co-exist with the first appearance of durophagous shell damage. The process of growing a mollusc shell is a remarkable phenomenon in itself, but mechanisms for repairing damaged shells should be regarded as an additional level of complexity. The fossil record does not provide us with a 3-stage story (i.e. no predation by shell breaking - predation without repair - predation accompanied by repair). The Chengjiang fauna document 'no predation by shell breaking'. The "slightly younger" Guanshan fauna documents 'predation accompanied by repair'. This leaves open the issue of the origin of the repair mechanism - did it evolve rapidly under the influence of natural selection? - is this a pointer to design?

"[T]he healed fractures show sets of distinctive drape-like arches of shell repairs, which markedly differs from the marginal concentric secretion of shell complements on scars in the mollusk Marocella described by Skovsted et al. (2007) from the Mernmerna Formation and Oraparinna Shale of South Australia, thus implying that a wider range of shell repair mechanisms evolved in different Cambrian shelly organisms of concentric accretionary growth."

3. When lingulids experienced selection forces associated with predation, they did respond, but remained lingulids. The exquisite preservation of the fossils has allowed soft tissue preservation: the pedicle used to anchor the animal in sediment. Lingulids subsequent to the Cambrian have a muscular pedicle and thick shells, as is appropriate for a burrowing infaunal lifestyle. However, the Lower Cambrian lingulids are different. The pedicles are more delicate and are suggestive of a semi-infaunal lifestyle "with only the pedicle buried in deep sediments for its anchorage and the anterior marginal shell margin tilted upwards". Thus, the Lower Cambrian lingulids were vulnerable to predation and selection pressures favoured animals that buried deeper into the sediments. By the Ordovician, this change was complete, and it never changes again in the fossil record. The stasis in Lingula was noted by Charles Darwin in Chapter XI of On the Origin of Species. He wrote: "The Silurian Lingula differs but little from the living species of this genus; whereas most of the other Silurian Molluscs and all the Crustaceans have changed greatly." (Source here) The case of Lingula is therefore a fascinating one: an abrupt appearance in the Lower Cambrian with a semi-infaunal lifestyle; durophagous-style predation by Stage 4 of the Lower Cambrian; adaptive change to a burrowing infaunal lifestyle followed by stasis (earning the extant Lingula the right to be called a living fossil). This case study illustrates well the empirical evidence relating to the capabilities of natural selection acting on natural variations. There is no sign of the evolution of complexity, but only the fine-tuning of existing complexity.

There are implications here for the study of evolution. The research community needs to be more aware of the limitations of proposed mechanisms (in particular, the Darwinian mechanisms of mutation and natural selection). It is not good enough to point to industrial melanism or Galapagos finches and claim that here is evolution in action! These examples simply do not address the challenge of building biological complexity. As researchers become more aware of the limitations, it will become apparent that the most appropriate context for analysing natural selection is not evolutionary biology - but ecology.

First record of repaired durophagous shell damages in Early Cambrian lingulate brachiopods with preserved pedicles
Zhifei Zhang, Lars E. Holmer, Sean P. Robson, Shixue Hu, Xiangren Wang and Haizhou Wang.
Palaeogeography, Palaeoclimatology, Palaeoecology, 302, (March 2011) 206-212 | doi:10.1016/j.palaeo.2011.01.010

Durophagy, the macro-predatory consumption of hard-shelled organisms, has been proposed as an important driving and selective force ("arms race") responsible for the explosive advent of Cambrian skeleton-bearing animals. Nevertheless, the direct evidence of durophagous predationis mostly restricted to borings or drill holes in skeletons at around the Ediacaran–Cambrian transition. In contrast, pre-ingestive breakage or crushing of shell, another important type of durophagous predation evidence, is very rarely fossilized. Here we present the first evidence of durophagous shell-breaking in an exceptionally preserved pedunculate lingulate brachiopod from the Lower Cambrian Wulongqing Formation (Series 2, early Stage 4), Yunnan, southern China. The repaired shells of Diandongia pista all have elongate (up to 36 mm) pedicles that demonstrate that they survived the failed predation and remained in situ. The bite embayment shows three sets of distinctive drape-like convex arcs of shell repairs, suggesting that the specific drape-like ornamentation usually seen in lingulate shells could be taken as reparative responses to shell damage and malformation. Discovery of sublethal shell damage demonstrates that durophagous predators may have caused an increasing predation pressure on brachiopods since the Canglangpuian Stage (Series 2, Stage 4). In contrast there are no records of durophagous shell-breaking recognized from thousands of Chengjiang (Series 2, Stage 3) specimens of D. pista with fully developed organization of tissues and organ system. It is therefore assumed that that predation was of little importance to the earliest evolution of Cambrian lingulates.

Daniel Brooks is has been living with controversy ever since 1982, when his ideas first appeared in an academic paper, and then when, in 1986, he co-authored with Ed Wiley a book with the title Evolution as Entropy. As well as promoting the idea that evolutionary diversification is to be understood as inevitable because it represents an increase in entropy, he also argued that the theory proposed was an alternative to Neo-Darwinism (widely known as the New Synthesis). In a commentary in Science, Lewin (1982) explained that:

"Responses to the proposal have been mixed and often quite strong. Some consider the theory to be a brilliant insight that will advance evolutionary biology immeasurably. Others vehemently reject it as an ill-founded attack on neo-Darwinism. Curiously, yet others regard it as nothing but neo-Darwinism translated into incomprehensible form. Still others contend that Brooks and Wiley's use of nonequilibrium thermodynamics is untenable in this context."

Evolutionary theories are said to be in the melting pot - but is there a place for design? (Source here)

The background to the 1982 paper was the burgeoning disquiet with Neo-Darwinism. Gould and Eldredge led the way with their assault on gradualism in the fossil record. Brooks recounts his own involvement with a small band of pioneering rebels:

"By 1982, the centenary of Darwin's death, Niles Eldredge and Steven J. Gould had catalyzed a loosely connected group of evolutionary biologists unhappy with the New Synthesis to unleash a cascade of criticisms and proposals. Emboldened by this display of the scientific community at its meritocratic best, Ed Wiley and I entered the fray. The day we finished proofreading Evolution as Entropy, David Hull presciently warned us the fun was over. Soon, I received an envelope from a friend who had seen a manuscript on a colleague's desk. Such privileged material is rarely copied and forwarded. My friend wrote, "I think you and Ed should know what you're up against." The privately circulated manuscript was authored by three academics at the University of California-Berkeley. Ed and I were stunned by its vicious tone. Why the rhetorical heat?"

Intense hostility to new ideas is often because people feel threatened. There is typically more heat than light. Brooks found this an instructive lesson in both the philosophy of science and the sociology of science.

"Hull (1988) proposed that most scientists, regardless of age, don't like new ideas, even ones that support their own worldview ("I already know that, why do I need this?"). They will fight to keep new ideas from becoming accepted unless they benefit their own careers. Ambitious scientists denounce new ideas, co-opting them once the originators have been frightened into silence or to marginal publication outlets. Eldredge's fundamental findings about the nature of the New Synthesis were equally bold - it had all the trappings of a marriage of convenience and none of the appearances of a consensual union. Thus, the status quo reaction to punctuated equilibrium and the other new ideas was a defense of a sociological arrangement, not of a set of scientific principles."

Yet, with the passing of time, with the retirement of senior figures and the entrance of young blood, the landscape of the debate has come to look rather different. Ideas once considered taboo were co-opted into mainstream thought ("we've always believed this"). A willingness to consider alternatives to Darwinism has arrived.

"Again, there are calls for changes in evolutionary theory. This time, the calls are met with celebration - we almost beg for an Extended Synthesis, some new and fresh framework that allows us to celebrate our legacy and add new findings to it. The lack of negative emotion may reflect the co-opting and rebranding of controversial concepts suggested by Brooks and Wiley, Eldredge and Gould, and many others. But again, I think this is an incomplete explanation because it does not explain the positive emotion, which I believe is linked to 1982, through a second atavistic reaction - new life from old, the continuation of life, the extension of life into the future, even notions of renewal and resurrection."

Brooks' search for a way forward led him to the view that Neo-Darwinism differs from Darwinism "on a number of important issues". He refers to the New Synthesis as the "Hardened Synthesis". Nine statements are presented to show the difference between Darwin's view (as expressed in the sixth edition of the Origin) and views held by neo-Darwinians. Brooks argues strongly that changes in evolutionary theory are overdue.

"The eclipse of Darwinism began to end in the 1980s and hangs in the balance today. We need an Extended Synthesis, using "extension" metaphorically. We must extend back in time to recover important aspects of Darwinism that were set aside, then lost during neo-Darwinism, then move forward beyond neo-Darwinism to encompass new data and concepts."

In many ways, this brings us to the beginning of a debate - one which accepts that the neo-Darwinian hegemony on evolutionary theory has to be overthrown and space created for those who are seeking to encompass new data and develop new concepts. Some of us are less optimistic than Brooks that we have reached this stage. Nevertheless, this is the stage which is needed in order to provide a framework for productive discourse about evolutionary biology. ID biologists have constructive things to say on each of Brooks' proposals about the way forward. The reason why these contributions are not welcome is that ID scholars are not materialists and they have concluded that the hallmarks of intelligent design are to be found in nature. Thus, ultimately, objections to ID are not scientific but metaphysical. Failure to appreciate this point will consign the academic world to an impoverished debate which excludes avenues of thought on ideological grounds.

The Extended Synthesis: Something Old, Something New
Daniel R. Brooks
Evolution: Education and Outreach, (March 2011) 4(1), 3-7 | DOI 10.1007/s12052-010-0304-3

Abstract: The eclipse of Darwinism began to end in the 1980s and hangs in the balance today. We need an Extended Synthesis, using "extension" metaphorically. We must extend back in time to recover important aspects of Darwinism that were set aside, and then lost during neo-Darwinism, then move forward beyond neo-Darwinism to encompass new data and concepts. The most comprehensive framework for the Extended Synthesis is the Major Transitions in Evolution. The Extended Synthesis rests comfortably within a philosophical perspective in which biology does not need to be connected with other areas of science in order to justify itself. I am attracted to an older concept in which biology needs a covering law to connect it with the rest of the natural sciences. Darwin implicated a "higher law," but did not specify it. If we can elucidate that law, the Extended Synthesis will become the Unified Theory of Biology called for by Brooks and Wiley 25 years ago.

See also:

Lewin, R. A Downward Slope to Greater Diversity, Science, 24 September 1982, 217, 1239-1240 | DOI: 10.1126/science.217.4566.1239

Earth systems science is concerned with the relationships between the various components that comprise the Earth as a system, notably environmental and biosphere interactions. Over the years, a wide spectrum of views has been expressed by scholars. At one extreme, the environment is the dominant influence, driving evolution within the biosphere (which is interpreted as being largely moulded by environmental forces). As an example, many have considered that changes in seawater chemistry and atmospheric oxygen levels triggered the Cambrian Explosion. At the other extreme, the Earth's environment can be perceived as the product of the biosphere. This is the position of Nicholas Butterfield, who has written a paradigm-shifting essay saying:

"it is clear that animals figure disproportionately in the maintenance of the modern Earth System, not least because they invented it."

Understanding the complexities of the Earth System is at an early stage (Source here.)

Earth systems thinking has a bearing on our approach to the environment. Is the Earth unstable, easily nudged to 'tipping point' and environmental melt-down? Alternatively, is it resilient, with negative feedback mechanisms operating to restore ecosystems to equilibrium? An inherently unstable Earth appears to be the verdict of Lenton and Watson in their book Revolutions that made the Earth (recently reviewed in Nature). They express concern about the effects of human activity that could destabilise our current planetary state. The reviewer draws attention to three other contributions to Earth System thinking:

"Lenton and Watson's thought-provoking book is the latest in a distinguished line of works that have altered our perception of the planet. Russian-Ukrainian geochemist Vladimir Vernadsky first discussed the deep involvement of life in planetary chemistry in his 1926 book Biosfera (Biosphere). In Gaia (Oxford University Press, 1979), James Lovelock brought the self-stabilizing mechanisms of life into view by seeing the planet as a partially self-regulating, living whole. And Hans Joachim Schellnhuber's book-length chapter in Earth System Analysis (Springer, 1998) laid out a blueprint for a scientific discipline concerned with the interplay of social and environmental dynamics."

Central to Butterfield's analysis is the transition from past environments where animals were absent to past environments where animals were plentiful. Animals were absent in the Proterozoic, and their numbers were much reduced after some of the great mass extinction events documented by the rock and fossil record. This is Butterfield's comment:

"In the absence of relatively large-celled eukaryotic phytoplankton, a positive feedback loop of cyanobacteria-induced turbidity is likely to have excluded higher light-demand eukaryotic algae (both phytoplankton and benthic macrophytes) from all but the most oligotrophic or shallow-water marine settings, thereby inducing widespread oceanic stratification. Stratified, bacterially dominated oceans are a signature of the Proterozoic and have generally been viewed in terms of atmospheric oxygen availability. However, without the water-clearing abilities of suspension-feeding animals, there would have been no mechanism for tipping the system out of this condition, irrespective of ambient oxygen. It is simply the default structure of aquatic ecosystems in an exclusively microbial world."

By contrast, oceans with animals are totally different.

"Organism size lies at the core of aquatic ecology and, in the modern ocean, ranges over 20 orders of magnitude, mostly by virtue of the extended trophic tiering of animals. Without such activity, micrometer-sized phytoplankton are not converted to millimeter-sized zooplankton, centimeter-sized zooplanktivorous fish, decimeter-sized piscivores, and so on. [. . .] Significantly, the body-fossil record of large, ornamented and/or biomineralized phytoplankton is limited exclusively to the Phanerozoic, especially in the highly escalated post-Paleozoic oceans, and fossil biomarker molecules point to a fundamental shift in marine export production accompanying the early radiation of animals: from primarily bacterial during the Proterozoic to primarily algal during the Phanerozoic."

The transition took place in the Ediacaran: that window of time between the end of the Precambrian and the beginning of the Phanerozoic. This was the biggest ecological revolution that has been documented in the rock record. Until recently, we had not realised how dramatic the environmental changes were: Butterfield refers to "some of the most pronounced biogeochemical perturbations in Earth history" and to "unprecedented shifts in C and sulfur cycling, iron geochemistry, phosphate deposition and oceanic oxygenation". Even more significant is the question: what was driving these changes? Why did the stratified, anoxic waters of the Proterozoic not persist? Butterfiled rightly questions the consensus view that incremental changes just happened and they were conducive to animal evolution.

"What is missing from such hypotheses, however, is an appreciation of just how pervasive the role of animals has been in defining the modern Earth system. By facilitating and forcing the diversification of, for example, eukaryotic phytoplankton, large body size, bioturbation and biomineralization, early animals reinvented the chemical interchange between the biosphere and planet. In this light, the biogeochemical perturbations of the Ediacaran-Cambrian interval are more likely to be the top-down consequences of animal evolution than its bottom-up cause. Early animals did not simply fill up previously existing but unoccupied niche space; they created the space itself."

If this radical idea is correct, it transforms our approach to ecology. It provides a different perspective on mass extinction events and global recovery:

"One approach is to examine the effects of Phanerozoic mass extinctions, which preferentially eliminate the largest and most specialized animals (and their associated 'ecosystem services'). Mass extinctions differ in their intensity, causes and evolutionary context, but in the oceans they are commonly accompanied by widespread stratification, bottom-water anoxia and spikes in cyanobacterial export. These intermittent returns to pre-Cambrian conditions point strongly to the top-down control not only of phytoplankton diversity, but also Phanerozoic ocean structure in general."

The implications of this new approach for evolutionary theory are not discussed by Butterfield. However, it seems to me that there are many. Most evolutionary biologists are quick to sign up to the importance of environmental changes as a driver for evolution, but the new approach presents much of this environmental change as an effect, not a cause. Modern Darwinists love the adaptive landscape model of evolutionary transformation, but the new approach considers that the "biosphere 'as we know it' is a space designed by metazoans". Environmental changes are frequently suggested to 'trigger' evolutionary transformation, but the hypotheses never get to the stage where they can be tested. Regular readers of this blog will be aware that I have been promoting the idea that the fossil record is not so much a story of evolutionary transformation as a history of the Earth's colonisation (go here for a recent blog on this theme - with links to earlier blogs). This conceptual model interfaces well with Butterfield's proposed Earth System.

"All organisms alter their physical environment to some degree, but the unique attributes of animals makes them particularly powerful 'ecosystem engineers'. Simply as a consequence of their motility, metazoans mix, ventilate and chemically alter the media though which they move. Such bioturbation is all but ubiquitous in modern soils and soft sediments, and imparts a first-order control over everything from sediment composition to landscape topography and biogeochemical exchange."

Animals and the invention of the Phanerozoic Earth system
Nicholas J. Butterfield
Trends in Ecology & Evolution, 26(2), February 2011, 81-87 | doi:10.1016/j.tree.2010.11.012

Abstract: Animals do not just occupy the modern biosphere, they permeate its structure and define how it works. Their unique combination of organ-grade multicellularity, motility and heterotrophic habit makes them powerful geobiological agents, imposing myriad feedbacks on nutrient cycling, productivity and environment. Most significantly, animals have 'engineered' the biosphere over evolutionary time, forcing the diversification of, for example, phytoplankton, land plants, trophic structure, large body size, bioturbation, biomineralization and indeed the evolutionary process itself. This review surveys how animals contribute to the modern world and provides a basis for reconstructing ancient ecosystems. Earlier, less animal-influenced biospheres worked quite differently from the one currently occupied, with the Ediacaran-Cambrian radiation of organ-grade animals marking a fundamental shift in macroecological and macroevolutionary expression.

See also:

Lucht, W., Earth systems: Shaped by life, Nature, 470, 460-461 (24 February 2011) | doi:10.1038/470460a

The last decade has witnessed three contenders for the title: earliest identifiable human ancestor. These are Ardipithecus, Orrorin and Sahelanthropus. All of them generated great excitement at the time of their discovery and, for many, they were evidence that the lineage of the human genus was being clarified. However, those willing to read research papers (rather than media reports) were more aware that the research community was not of one mind about the significance of these fossil remains. Recently, Wood and Harrison have contributed a major review paper that revisits these arguments and finds that the various claims for human ancestry are not rigorous. They offer alternative explanations for these three fossil hominines.

"In their paper, Wood and Harrison caution that history has shown how uncritical reliance on a few similarities between fossil apes and humans can lead to incorrect assumptions about evolutionary relationships. They point to the case of Ramapithecus, a species of fossil ape from south Asia, which was mistakenly assumed to be an early human ancestor in the 1960s and 1970s, but later found to be a close relative of the orangutan." (source here)

Listed as Breakthrough of the year 2009, but we do need to ask - "is Ardi a man and a brother?" (source here)

The key arguments are presented in a section of their paper entitled: "Shared morphology need not mean shared history". They refer, in particular, to three anatomical characteristics. The first is concerned with canine morphology, the second with the location and orientation of the foramen magnum, and the third with features of the pelvis and other bones that have implications for bipedalism. These character traits have been prominent in discussions of the significance of Ardipithecus, Orrorin and Sahelanthropus. The problem identified by Wood and Harrison is homoplasy, where the same biological trait appears in unrelated lineages. Homoplasy leads to false homologies. The authors express their concerns in this way:

"The important point is that shared similarities can only take one so far in determining phylogenetic relationships, because homoplasy, as well as uncertainties in determining the polarity of character transformation, have the potential to generate substantial noise that serves to confound attempts to generate reliable hypotheses about relationships. These considerations have clear implications for generating hypotheses about the phylogenetic position of Ardipithecus, Sahelanthropus and Orrorin. Even if these taxa share some derived features with later Pliocene hominins, it would be rash simply to assume that those features are immune from homoplasy, especially when other aspects of their respective phenotypes are consistent with a more distant relationship with the hominin clade."

There is also concern expressed about the 'linear' model of human evolution that seems to be promoted by some zealous researchers. There is no reason why a linear trajectory should be expected. A year ago, Harrison published a paper drawing attention to the remarkable diversity of fossil apes from the Miocene with a great variety of character traits. This is the complexity which needs to be recognised by researchers.

"There is no reason why higher primate evolution in Africa in the past ten million years should not mirror the complexity observed in the evolutionary histories of other mammals during the same time period. Nor is there any reason, especially with the lessons from Ramapithecus and Oreopithecus fresh in the minds of researchers, to assume that hominins should not be prone to the same limitations and uncertainties of phylogenetic analysis as other fossil primates."

What about Ardi? The authors views were clearly presented in a blog for Scientific American.

"I think it's equally likely, or perhaps even preferable, that it is an ancestral form or an early representative of the African great ape" group - that "it's not necessarily uniquely linked to humans," Harrison said of Ardipithecus [. . .].
Some of the most solid evidence for Ardi being included in the hominin branch is her small canine teeth. But the researchers are quick to point out that other ancient non-hominin species, including Oreopithecus and Ouranopithecus, also came to have reduced canine teeth, "presumably as a result of parallel shifts in dietary behavior in response to changing ecological conditions," the researchers suggest in their article. "Thus, these changes are in fact, not unique to hominins."
The placement of a hole at the base of the skull, known as the foramen magnum, also might suggest Ardi as an upright walker, and thus perhaps a solid hominin. But in looking to other apes, "this feature is more broadly associated with differences in head carriage and facial length, rather than uniquely with bipedalism," Wood and Harrison note. Some extinct primates, such as Oreopithecus bambolii, evolved outside of the human line but nevertheless possessed similarly hominin-like traits, which, the authors write, "encourage researchers to generate erroneous assumptions about evolutionary relationships."

A helpful overview of the issues is provided by by Brian Switek in his Laelaps blog. Significantly, he uses the title "Ancestor Worship", which captures the reasons for the way these fossil finds are hyped up. Science News succeeded in communicating the strong feelings accompanying this academic debate: "Researchers have to stop publishing papers that say, essentially, 'This fossil is an early hominid, so suck it up and accept it'," Wood says. "Nature and Science could change this practice overnight if they wanted to."
The other side of this controversy is represented by Tim White, champion of Ardi. His comments reveal a stubborn resistance to the message of the paper:

"With no new data, no new ideas, no new methods, no new hypothesis, no new experiments, no new fossils, not even a new classification, this paper will leave everybody wondering what's happened to the peer review process at Nature," White says.

What is to be made of all this? Wood and Harrison are comfortable with the big picture - the pattern of relationships between humans and the great apes as revealed by molecular evidence. Their concern is to inject more caution into the analysis and reporting of new fossil material. Researchers need to be alert to convergent evolution, unrelated to ancestry. A previous blog drew attention to the way the fossil record of human evolution can be likened to a pointillist painting (here) and this analogy still seems relevant. We have lots of data points, but only when we stand back does a picture emerge. However, the picture that emerges reflects very much what we bring as observers. When we expect an evolutionary story, it is possible to see one, but proving that there really is an evolutionary story is quite another matter.

The evolutionary context of the first hominins
Bernard Wood & Terry Harrison
Nature, 17 February 2011; 470, 347-352 | DOI: 10.1038/nature09709

Abstract: The relationships among the living apes and modern humans have effectively been resolved, but it is much more difficult to locate fossil apes on the tree of life because shared skeletal morphology does not always mean shared recent evolutionary history. Sorting fossil taxa into those that belong on the branch of the tree of life that leads to modern humans from those that belong on other closely related branches is a considerable challenge.

See also:
Bower, B. Human Ancestors Have Identity Crisis, Science News (February 17, 2011)

Fossils May Look Like Human Bones: Biological Anthropologists Question Claims for Human Ancestry, ScienceDaily (Feb. 16, 2011)
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Harmon, K. Was "Ardi" not a human ancestor after all? New review raises doubts, Scientific American (Observations blog, Feb 16, 2011).

Switek, B. Ancestor Worship, Laelaps (February 22, 2011)