There are two competing paradigms about Neanderthal capabilities and culture. The first considers Neanderthals to be cognitively inflexible, with a limited use of technologies that was unresponsive to environmental change. The second recognises a much wider range of behaviours and technologies, with adaptation to specific local conditions. The paper considered in this blog belongs to the second of these perspectives: the reported work considers artefacts from a cave that was occupied by Neanderthals and dated about 90,000 years ago.
"Here, we present evidence for behavioral variability and complexity among Neanderthals at the beginning of Marine Isotope Stage 4 (MIS 4) at the Abri du Maras located above the Ardeche River in southern France. Using residue analysis of stone tools with supporting evidence from zooarchaeology, we show that Neanderthals at the Abri du Maras had a detailed knowledge of their surrounding environment, captured fast and agile prey (rabbits, fish and birds), exploited a range of plant species, and used composite technology such as hafted stone points and the manufacture of string and cordage. Overall, we present evidence which demonstrates that Neanderthals at the Abri du Maras were far from inefficient foragers." (p.24)
Not just a pretty face (Image: Nikola Solic/Reuters, source here))
Many flake stone tools have been recovered. Microscopic examination of their surfaces has revealed a remarkable variety of traces providing clues about Neanderthal capabilities and lifestyle. The most noteworthy relates to tiny fragments of twisted plant fibres. This is considered to be evidence for human activity: gathering plant material, retting or shredding to extract fibres, twisting to create threads or string, and cutting a length with the stone tools.
"These fibers are not twisted in their natural state which suggests that they were twisted by the inhabitants of the Abri du Maras and may therefore provide evidence of the manufacture of string or cordage. In previous woodworking experiments involving incising, planning, whittling, scraping, and boring, no twisted fibers were observed. Unpublished experiments conducted by BH involving the scraping, cutting, and slicing of a variety of nonwoody plants (roots, tubers, reeds, etc.) also produced no twisted fibers such as those observed here. While not definitive, the lack of twisted fibers in these experiments lends some credence to the hypothesis that these derive from cordage. Future experiments involving cordage and plant processing will help clarify the potential sources of twisted fiber." (p.27,29)
Circumstantial evidence is provided by observations of micro-wear of flake tools that show indications of being hafted to produce stone-tipped javelins. Other uses for string can be inferred because there is evidence at this site that Neanderthals went fishing and at other sites that they crossed open water in boats.
"Since macroscopic remains have not been found prior to 19 ka, it is important to examine other less direct forms of evidence where fiber or string production may leave traces on a microscopic level which may be visible through use-wear and residue analyses. For most of the Paleolithic, the best potential source of evidence for cordage is stone tools. Hurcombe (1998) describes several different points in the chaine operatoire of fiber production where stone tools are likely to be used, including plant harvesting, processing of fibers, and cutting loose ends from cordage.
The production of string along with simple knowledge of knotting, weaving, and looping, make possible a wide range of products including "nets, containers, packaging, baskets, carrying devices, ties, straps, harness, clothes, shoes, beds, bedding, mats, flooring, roofing and walling". In addition, string facilitates the construction of complex, multi-component technologies such as hafts or snares. Finally, string would have been essential for seafaring, maritime technologies used for the colonization of islands, and for many types of fishing." (p.34)
We cannot consider all the evidences discussed by the authors. However, they make an interesting comment on how expectations (influenced by presuppositions) affect research programmes.
"Paleolithic archaeologists have a tendency to focus heavily on reconstructing subsistence activities. Within subsistence, the focus is primarily on animals with even more narrow focus on large animals, partly because their remains preserve better. This focus is justified to some extent as archeologists can only work with the evidence they find. However, this means we are missing a huge component of everyday life. The preservation bias of the archaeological record limits the avenues being investigated. The fiber evidence presented here is a reminder that if we don?t look for it, we won?t find it." (p.35)
We shall pass over much interesting discussion of evidences and reach their conclusion. The authors have used their detective skills to reconstruct a community of Neanderthals that appears to be indistinguishable from modern humans.
"The Abri du Maras overlooks the Ardeche River in south-eastern France. The combination of analyses presented here (mainly residue analysis) has provided a more detailed view into Neanderthal lives than is generally possible. Neanderthals at the Abri du Maras caught and consumed a wide variety of foods, from large herbivores to rabbits, fish, plants, and possibly birds. The occupants of the Abri du Maras may have also been engaged in a variety of other activities: gathering mushrooms, gathering raw materials and manufacturing string, woodworking, constructing composite technologies such as complex projectiles and possibly nets or traps. Given the wide variety of resources exploited at the Abri du Maras, we should heed Hockett's recent caution that we may have "under-appreciated the amount of non-mammal foods eaten by Neanderthals". We would add that the high diversity of resources used by Neanderthals has been generally under-appreciated for decades." (p.38)
This fascinating insight into community life is worthy of our attention because the group members were Neanderthals. For too long, they have been portrayed as pre-human and have been used to buttress evolutionary stories about the origins of mankind. However, archaeological evidence discussed here (and here) suggests that these stories are embellished with evolutionary spin. The evidence shows that Neanderthals are human cousins and deserve quite a different place in history. Unfortunately, this truth about Neanderthals has been missed in the past because the presumption of evolutionary transformation has constrained the minds of researchers. They illustrate the maxim: "if we don't look for it, we won't find it."
Another recent finding that is related to this theme is that a Neanderthal community in Italy organised their cave in a way that is recognisably human. The punchline is the same: here are "close cousins" that do not deserve to be called pre-human.
"Scientists have found that Neanderthals organized their living spaces in ways that would be familiar to modern humans, a discovery that once again shows similarities between these two close cousins. The findings, published in the latest edition of the Canadian Journal of Archaeology, indicate that Neanderthals butchered animals, made tools and gathered round the fire in different parts of their shelters. "There has been this idea that Neanderthals did not have an organized use of space, something that has always been attributed to humans," said Julien Riel-Salvatore, assistant professor of anthropology at the University of Colorado Denver and lead author of the study. "But we found that Neanderthals did not just throw their stuff everywhere but in fact were organized and purposeful when it came to domestic space." [snip] "This is still more evidence that they were more sophisticated than many have given them credit for. If we are going to identify modern human behavior on the basis of organized spatial patterns, then you have to extend it to Neanderthals as well." (source here).
Impossible Neanderthals? Making string, throwing projectiles and catching small game during Marine Isotope Stage 4 (Abri du Maras, France)
Bruce L. Hardy, Marie-Helene Moncel, Camille Daujeard, Paul Fernandes, Philippe Bearez, Emmanuel Desclaux, Maria Gema Chacon Navarro, Simon Puaud, Rosalia Gallotti
Quaternary Science Reviews, Volume 82, 15 December 2013, Pages 23?40
Abstract: Neanderthal behavior is often described in one of two contradictory ways: 1) Neanderthals were behaviorally inflexible and specialized in large game hunting or 2) Neanderthals exhibited a wide range of behaviors and exploited a wide range of resources including plants and small, fast game. Using stone tool residue analysis with supporting information from zooarchaeology, we provide evidence that at the Abri du Maras, Ardeche, France, Neanderthals were behaviorally flexible at the beginning of MIS 4. Here, Neanderthals exploited a wide range of resources including large mammals, fish, ducks, raptors, rabbits, mushrooms, plants, and wood. Twisted fibers on stone tools provide evidence of making string or cordage. Using a variety of lines of evidence, we show the presence of stone projectile tips, possibly used in complex projectile technology. This evidence shows a level of behavioral variability that is often denied to Neanderthals. Furthermore, it sheds light on perishable materials and resources that are not often recovered which should be considered more fully in reconstructions of Neanderthal behavior.
A Spatial Analysis of the Late Mousterian Levels of Riparo Bombrini (Balzi Rossi, Italy)
Julien Riel-Salvatore, Ingrid C. Ludeke, Fabio Negrino, and Brigitte M. Holt
Canadian Journal of Archaeology, 37(1), 70-92 (2013)
Abstract: We present a preliminary analysis of the spatial distribution of various artifact classes in the Late Mousterian levels of Riparo Bombrini (northwest Italy). This work shows the presence of a consistent gap in artifacts across all levels, which is interpreted as reflecting the position of the dripline prior to the shelter's collapse. Hearths are identified in levels M1-3, M4 and M5, and their position at the back of the shelter is similar to that of "sleeping hearths" identified at other Mousterian sites. Lastly, the distribution of artifacts is shown to co-vary with the nature of the prevalent mobility strategies in use at different times over the site's occupational history. Notably, use of the site as a logistical base camp is correlated with the presence of hearths and the accumulation of noisome debris beyond the dripline and outside of the shelter. Other uses of the site seem to have favored the discard of some classes of artifacts within the shelter itself. This shows that Neanderthals were indeed able to organize their use of space in patterned and somewhat predictable manners, and that the length and nature of their occupation of the rockshelter need to be taken into account in such analyses.
I bought a copy of "The Explanation of Everything" by Lauren Grodstein. The book was an interesting read on relationships to be sure, but the ID/atheist debate was as deep as a mountain stream near its source. In the book, one female Christian has sensual urges which she acts out on the professor. Her pastor has a curious theology, at least from a Protestant worldview, which he apparently holds. The quirky male believer does an about fact to atheism. Meantime the atheist professor oddly feels the ghost of his departed wife while still an atheist, and becomes a theist, or should I say, a deist.
I was hoping for more on the debate side...
Read the ENV article by David Klinghoffer.
Earlier this year, in March, Nature reported that soft-bodied worms from the Burgess Shale fossil beds in Canada, given the name Spartobranchus tenuis, have been identified as ancient examples of acorn worms. They were hailed as a "missing link" in the vertebrate family tree: "a crucial evolutionary link between two distinct living groups of animals: enteropneusts and pterobranchs." The evidence supporting this was said to be the tubes constructed by Spartobranchus tenuis. Living enteropneusts (acorn worms) do not have tubes, whereas living pterobranchs (minute colonial organisms) do. Professor Simon Conway Morris affirmed the significance of the newly discovered fossil tubes with these words: "By finding enteropneusts in tubes we begin to bridge this evolutionary gap." At the time, these issues were discussed in a blog here, and questions were raised about the evolutionary narrative. More now needs to be said, as a recent paper in Nature Communications has documented modern tube-forming acorn worms found in Antarctic benthic communities.
Figure 1b: Large purple morphotype in secreted tube with proboscis expanded. (Source here)
Recent work surveying life in ocean basins has identified a new family of deep-sea enteropneusts, the Torquaratoridae. During oceanographic cruises in the Antarctic, between 2008 and 2013, two new enteropneusts were discovered at depths ranging from 531 to 1,111m. These species secrete translucent tubes in which they live, although they have also been observed abandoning their tubes. The authors recognize that their discovery is directly relevant to the interpretation of the Burgess Shale worm tubes. This is their discussion:
"Foremost, our discovery provides context for the recently re-described Middle Cambrian fossils, S. tenuis from the Burgess Shale Formation. These acorn worm fossils look remarkably like present-day enteropneusts, except many are observed to be within a 'fiberous' tube. The persistence of tubes in Antarctic worms suggests that the tubes contain proteinaceous components functioning as binding agents. Some tubes were lightly covered with sediment giving them a 'ribbed' appearance, similar to those reported for S. tenuis. [. . .] Our observations of Antarctic tubicolous worms and faecal casings imply that the worms often turn and zigzag during movement or may even double back on themselves as reported elsewhere. If buried quickly in a single obtrusion event, as suspected for each of the mudstone beds of the Greater Phyllopod Bed (that is, Walcott's quarry), such tubes could appear helical or even circular as reported for S. tenuis [. . .]. The fossil tubes were interpreted as 'fiberous' based on apparent tearing of the tubes, but a similar phenomenon occurs with the present-day tubes. Given the similarity in tube design between S. tenuis and the Antarctic torquaratorids, similar behavioural repertoires (for example, tube building, vacating tubes and meandering epibenthic movements) appear to have been conserved ~500 million years."
So, the discovery of modern tube-forming acorn worms has assisted the interpretation of the fossil tubes: the fibrous texture is an artifact of preservation and not part of the constructed tube, and the doughnut shapes are likely to be formed by a rapid depositional process and is not representative of the original structure in life. The evidence we have is of stasis in behavioral repertoires as well as in morphology.
This leads to a rather different conclusion about the implications for evolutionary theory. The idea that S. tenuis is a link between the enteropneusts and the pterobranchs lacks credibility. The argument is explained very clearly in the research paper:
"Fossil evidence reveals that graptolites, and even rhabopleurids and cephalodiscids (modern pterobranch lineages), were present in the Middle Cambrian, making S. tenuis contemporary with established pterobranch (including graptolite) lineages. As the split between enteropneust and pterobranch lineages would have been before the Middle Cambrian, the tube of S. tenuis was not a precursor to the pterobranch coenecium. Lack of synapticulae and hepatic sacs were also argued to ally S. tenuis with harrimaniid enteropneusts. However, torquaratorid enteropneusts, like harrimaniids, lack synapticles, and assessing the presence of hepatic sacs often requires microscopy in modern species, much less in fossilized ones. Given the position of torquaratorids and pterobranchs in hemichordate phylogeny, the last common hemichordate ancestor may have been able to build tubes, raising the question whether this ability was present in the last common deuterostome ancestor."
The implication is that the last common hemichordate ancestor lived before the Middle Cambrian and should be located before the Cambrian Explosion. The problem for this hypothesis is that there is a paucity of fossil data: we do not have anything other than speculation for hypothetical ancestors of the animal phyla. Instead of evolutionary theory having anchors in fossil evidence about the past, the Precambrian is effectively a blank sheet where inferences are drawn from selected phylogenetic data and produce conflicting evolutionary trees.
There is a pattern in the way fossil discoveries are reported. If they are deemed to fill in the gaps in a branch of the evolutionary tree, they generally get massive exposure and are hailed as milestones in developing an understanding of life on Earth. However, when new data comes to light that shows the original thinking to be wrong, the exposure is far less and the media show little interest. With acorn worms, we have a case to reflect on worthy of our time. The message we should be taking away is that the fossil record brings us evidence of stasis, not evolutionary transformation. We need a radical rethink of the presuppositions we bring to the story of life on Earth, because the present hegemony of Darwinism has no adequate explanation for the origin of biological information.
Modern Antarctic acorn worms form tubes
Kenneth M. Halanych, Johanna T. Cannon, Andrew R. Mahon, Billie J. Swalla and Craig R. Smith
Nature Communications, 4, No. 2738, 07 November 2013 | doi: 10.1038/ncomms3738
Abstract: Acorn worms, or enteropneusts, are vermiform hemichordates that occupy an important position in deuterostome phylogeny. Allied to pterobranch hemichordates, small colonial tube dwellers, modern enteropneusts were thought to be tubeless. However, understanding of hemichordate diversity is poor, as evidenced by absence of reports from some oceanic regions and recent descriptions of large epibenthic deep-water enteropneusts, Torquaratoridae. Here we show, based on expeditions to Antarctica, that some acorn worms produce conspicuous tubes that persist for days. Interestingly, recent fossil descriptions show a Middle Cambrian acorn worm lived in tubes, leading to speculation that these fossils may have been pterobranch forbearers. Our discovery provides the alternative interpretation that these fossils are similar to modern-day torquaratorids and that some behaviours have been conserved for over 500 million years. Moreover, the frequency of Antarctic enteropneusts observed attests to our limited knowledge of Antarctic marine ecosystems, and strengthens hypotheses relating more northern deep-sea fauna to Antarctic shelf fauna.
Birchfield, C. Auburn University researchers make deep sea creature discovery and set sail for Antarctica, Auburn University News, 20 November 2013.
Whether you are a diver, a geologist, or simply someone with an interest in natural history, you are likely to have a misconception about the structure of coral reefs. The error is ubiquitous in textbooks and is reinforced by media treatments of the topic. Everyone 'knows' that coral reefs have a central zone of organically bound material (the reef core), a leeward zone of flat lying sediments (the back-reef lagoonal area) and a seaward zone of steeply-dipping rubble (the reef talus). The misconception relates to the reef talus. The source of the erroneous view can be traced to Charles Darwin, who sought to follow his mentor (Charles Lyell) in explaining the past by reference to present-day processes.
"Darwin and his many followers regarded contemporary reefs as having shelf-like forms, with steep slopes facing deep water. This morphology differentiates the familiar zones of backreef, reef-crest and fore-reef. Most accounts emphasize the importance of the reef-crest, comprising the growth framework responsible for generating the reef structure. Material eroded from both the reef-crest and the upper reef-slope has been assumed to accumulate on the fore-reef, and it was argued that this provided the foundations that enabled construction to take place in waters that were otherwise too deep. This pervasive idea can be traced to Darwin (1842) and Dana (1853), although it typically only applies to windward, moderately high hydrodynamic energy, regimes. However, numerous conceptual models illustrate reefs in which the fore-reef is shown as a steep debris slope, on which depositional increments are correlated with contemporary intervals of reef growth." (from the Introduction).
An example of an educational graphic showing the fore-reef talus. (Source here)
This understanding of the fore-reef debris slope as talus is described as a "misconception", an "error", a "misleading description" - yet it has achieved widespread acceptance and is regarded as the "traditional" view and a "cherished model". This should be regarded as another example of 'consensus' thinking that owes more to the naive acceptance of Lyellian uniformitarianism than to science. We have Colin Braithwaite to thank for showing that the research findings over the past 30+ years demonstrate clearly that the textbook interpretations of "reef talus" need to be revised. After reviewing numerous papers, he writes:
"What conclusions, vis a vis Darwin's model and "talus slopes", can be drawn from these observations? Early descriptions of reefs by Darwin and others paved the way for an interpretation linking the morphology of 'the reef' to erosion and the formation of coarse debris, 'reef talus', commonly regarded as integral to conceptual models of ancient reefs. However, research over the past decades has shown that present-day processes, that include storm events at the high end of the energy spectrum, are important contributors to reef debris but do not generate large volumes of coarse debris on fore-reef slopes. Although reef erosion is a reality, transport directions generally preclude its involvement in large-scale talus formation. Neither off-reef flow nor large-scale slope failure generates debris on the reef front in the size ranges typically described as "talus"." (From the Conclusions)
Evidence amassed by Braithwaite explains that "reef talus" is a misnomer. In the main, it is not rubble from the reef core that has moved down the steeply-dipping fore-reef slope. The evidence shows that most of the reef debris caused by hurricanes and storms is moved in the other direction - into the back-reef lagoon. The mechanism is understood in this way:
"Why does such transport occur? It reflects wave set-up and the flow generated by breaking waves. However, in contrast to waves breaking on sand or gravel beaches, other than during relatively fair-weather conditions, backwash is effectively eliminated. Flow is able to continue landwards in waves of translation that decay gradually and, on a wide platform, are ultimately dissipated by surface friction. Thus, their ability to transport material is systematically reduced and is only expressed in a broadly decreasing grain-size of deposits landward of the reef margin." (From Section 3 - fore-reefs and transport)
Braithwaite argues that coral reefs in today's oceans are growing on limestone platforms that predate reef growth. The margins of those platforms are subject to a variety of forces that produce the talus slopes.
"Contemporary reefs are shedding sediment into deeper waters, but there is also evidence of larger-scale margin collapse and gravity-driven slope failure of the platforms beneath them. Blocks of kilometre dimensions have been described on the west Florida margin, the Bahamas, and bounding the Nicaraguan Rise." (From Section 5 - slope deposits and platform shedding)
For those with an interest in the geological issues, Braithwaite's discussion is informative and thought-provoking, but this will not be considered further here. Suffice to say that it incorporates plenty of examples from fossil 'reefs' that confirm the proposed model.
"The premise that "reef talus" is an expression of the erosional history of the underlying platform rather than an integral product of a living reef can be illustrated by examples from rocks of a variety of ages." (From Section 6 - Ancient analogues)
Braithwaite=s paper is suggestive of a distinction that can be made between uniformitarianism and actualism. Darwin illustrates the former - although he claimed to be saying that the present is the key to the past, he invoked only gradualist processes that he thought were operative in the present and failed to test his hypotheses rigorously. Those who have followed him appear to have lacked the will to formulate and test hypotheses and to consider the viability of alternative models. Although there is an appeal to contemporary processes, uniformitarians tend to favour those characterised by small incremental effects. By contrast, Braithwaite illustrates actualism, with an evaluation of a much wider range of processes. He considers hurricane-driven tidal flows, tsunamis, and even waves generated by a meteorite impact capable of lifting blocks weighing 100 tons onto cliffs 33m above present sea level. He cites a case of sediment accumulation over about 500 years but all of it being transported and dispersed by a hurricane-induced current in about 5 hours. He shows how alternative models can be tested and how evidence can be used to falsify hypotheses. This approach to science is much more healthy, for there is a willingness to challenge cherished models and an openness to the operation of different mechanisms.
Why is this worthy of our attention? The principles in evidence here are relevant to a large number of topics that relate to the past. Unfortunately, these origins issues often are characterised by excessive appeals to consensus and cherished models, and not enough attention is given to the weight of evidence. Lyell's and Darwin's uniformitarianism still have an undue influence on our educational system and the media. Attempts to increase the level of critical scrutiny are met with emotive responses rather than reasoned arguments. To help us think through our methodology for dealing with these tensions, Braithwaite's approach to the "reef talus" model may provide a useful case study.
Reef Talus: A popular misconception
Colin J.R. Braithwaite
Earth-Science Reviews, online 14 November 2013
Abstract: Reef fronts have traditionally been regarded as comprising debris derived by contemporaneous erosion of 'the reef'. However, evidence from wave transport indicates that on present-day reefs the bulk of the debris generated in this way accumulates in the back-reef area, with only finer-grained sediment carried off-reef by retreating flows or by overwash. Nevertheless, in contrast to this observation, 'fore-reef' debris slopes are commonly considered "characteristic" of Phanerozoic reefs. This apparent error reflects the conflation of processes defining contemporary growth and accretion of the reef, and the corresponding long-term accretion of the carbonate platform on which it rests. Present-day reefs are commonly (although not exclusively) additions to long-lived carbonate platforms. Growth of the latter is intermittent and has been moderated by changes in sea-level that, for recent reefs, have been on time scales of less than 100 ka. During low sea-level stands, growth ceases or is translated downslope and earlier deposits are subject to lithification and subaerial erosion. Similar changes are applied on a larger scale to the aggrading growth of carbonate platforms, but the bulk accretion of these includes quite different processes and reflects far longer timescales. During low sea-level stands, the margins of platforms commonly become unstable, with instability reflected in slope failure and in the shedding of blocks, ranging from metres to kilometres in diameter, associated with the generation of debris flows and turbidites. It is argued that these are the materials that are commonly described as 'reef talus' in ancient structures, although their formation is largely independent of any contemporary reef growth. Difficulties arise where 'the reef' and 'the platform' are treated as a single functional entity. It is important to recognize the conceptual distinction between them, 'reef talus' is a misleading description of the debris predominantly generated by platform erosion and slope failure.
Tyler, D. The unscientific hegemony of uniformitarianism, ARN Literature Blog (16 May 2011)
From ENV...The Texas State Board of Education looks set to approve science textbooks this week that fail to comply with state science standards requiring students to "analyze and evaluate" core evolutionary claims, according to a Discovery Institute scholar who advised the Board before it adopted the standards.
Dr. Stephen Meyer, author of the New York Times bestselling book Darwin's Doubt, served as a Board-appointed expert reviewer of the Texas science standards when the standards were originally developed in 2009.
Meyer expressed concerns that proposed textbooks would "leave students in the dark about contemporary mainstream scientific controversies over Darwinian evolution.
Just in time for the 50th anniversary of C.S. Lewis's death, a new documentary has been released exploring the beloved Christian writer's life-long struggle to find intelligent design in a world filled with cruelty, pain, and imperfection.
The documentary "C.S. Lewis and Intelligent Design" premieres on the NRB cable and satellite network and the YouTube C.S. Lewis Channel. The documentary was inspired by a book edited by Dr. John West titled The Magician's Twin: C.S. Lewis on Science, Scientism, and Society.
Raymond Bohlin holds a doctorate in molecular biology. He received his master's degree in population genetics, the study of how adaptation and speciation is expressed by DNA. In other words, he possesses more than a passing knowledge about the theory of evolution.
He could not believe that evolutionary mechanisms could account for the dizzying complexity he saw in the living world. It was easier for him to detect the work of some unseen force ? a designer's hand guiding a spontaneous appearance of species - behind the rise of complex life. It's the sort of completely untestable idea that doesn't gain much traction among the editors and reviewers of scholarly journals.
With the 50th anniversary of C.S. Lewis's passing on November 22, CSC associate director John West has written a book; The Magician's Twin: C.S. Lewis on Science, Scientism, and Society.
C.S. Lewis countered the argument from undesign with several positive arguments in favor of the existence of a transcendent intelligent cause for nature.
Palaeontologists have been developing some highly sophisticated tools for analysing fossil specimens. Of particular interest are techniques that probe the details of soft tissue preservation. In the research considered here, the 30 mm specimen was found at the Chengjiang lagerstatte locality in southwest China. It had large, claw-like appendages on its head and many jointed legs. It is assigned to the arthropods and thought to be a probable extinct chelicerate. It is referred to as one of the megacherian (meaning "great hand") species with the genus name Alalcomenaeus. To analyse the soft tissues, a 3-D model of the specimen was produced using a CT-scanner and, at the same time, an X-ray microscope documented the distribution of selected chemical elements. In particular, iron has been found to map out the nervous system of the animal. The findings are spectacular.
This close-up of the head region of the Alalcomenaeus fossil specimen includes superimposed colors of a microscopy technique that reveal the distribution of chemical elements in the fossil. Copper shows up as blue, iron as magenta and the CT scans as green. The coincidence of iron and CT denote nervous system. The creature boasted two pairs of eyes (ball-shaped structures at the top). (Image: N. Strausfeld/University of Arizona, source here)
Living arthropods are classified into two major groups: the chelicerata (which include spiders, scorpions, mites and horseshoe crabs), and the mandibulata (which includes insects, crustaceans and millipedes). The new research locates the "great appendage arthropods" unambiguously in the chelicerata.
"We now know that the megacheirans had central nervous systems very similar to today's horseshoe crabs and scorpions," senior author Nicholas Strausfeld, a professor in the department of neuroscience at the University of Arizona in Tucson, said in a statement. (source here)
"The animal's brain consists of three fused ganglia, and blends into more ganglia that extend down the length of the animal's body. It has four eyes, each of which is served by just one optic lobe. That's a chelicerate layout - in mandibulates, the body ganglia would be more distinct and separated by long nerves, and there would be two to four optic lobes per eye." (Ed Yong, source here)
Evolutionary biologists are very fond of the terms "stem" and "crown" to describe where fossils fit into the tree of life. A "stem" fossil is supposed to have more transitional characters and the "crown" specimens are essentially modern. These great appendage arthropods were previously interpreted as "stem group chelicerates" or "stem-group arthropods". However, the neural architecture is essentially modern.
"Professor Strausfeld said: 'Greg plugged these characteristics into a computer-based cladistic analysis to ask, "where does this fossil appear in a relational tree?" 'Our fossil of Alalcomenaeus came out with the modern chelicerates." (source here)
This research is actually the second study of its type. The first was concerned with the neural structure of a mandibulate organism, published last year.
"Xiaoya Ma and Nicholas Strausfeld described the brain of a 520-million-year old animal called Fuxianhuia protensa. It consisted of three clusters of nerves (ganglia) that had fused together. (Source here)
"Nerves from the second ganglion reached into the creature's antennae, while nerves from the third one led into a pair of claws. Each of the animal's eyes was served by three further nerve bundles, known as optic lobes. "In other words, the specimen had a brain like that of a modern crustacean," says Strausfeld. Fuxianhuia was clearly an early relative of modern crabs, lobsters and shrimp - a relationship that was unclear from its body alone. [. . .] Fuxianhuia exemplified the mandibulate pattern." (Source here)
"No one expected such an advanced brain would have evolved so early in the history of multicellular animals," said Strausfeld, a Regents Professor in the UA department of neuroscience. [. . .] "In principle, Fuxianhuia's is a very modern brain in an ancient animal." (Source here)
So we have the interesting situation that both groups of arthropods have neural patterns that are essentially modern. Whereas morphology is used to argue the case for "stem" and "crown" organisms, complex specified information is more readily discerned in soft tissues: genetic systems, developmental gene regulatory networks and neural patterns. Research over the past decade has indicated that numerous core genes are common to a large number of phyla with the implication being that they preceded the Cambrian Explosion of animal phyla (here and here). The same applies to developmental pathways. The research considered in this blog shows that the neural pathways for arthropods must be dated at least to the Early Cambrian. This provides an additional dimension to the Cambrian Explosion phenomenon - in that an extraordinary accumulation of biological information is already in place by the Middle Cambrian.
A final point to note relates to the way iron mineralisation has preserved neural patterns, for reasons that are not altogether clear. It appears that nerve cells are more resistant to decay than other soft tissues:
"Strausfeld says that the nerves of invertebrates are dense and rich in fats, which makes them water-repellent. This, combined with their hard external skeleton, might have slowed the process of decay long enough for them to fossilise. Indeed, in an earlier study, Strausfeld's team buried marine worms in mud and put them under high pressure to simulate the start of fossilisation - and their nerves lasted while their muscles decayed." (source here)
Whilst there is a rationale for nerve tissue surviving longer than other tissues, it remains to be discovered why nerve tissue should take up iron mineralisation. Is there something about the nerve cells that attracts iron? All are agreed that soft tissue preservation requires rapid fossilisation, but we may find that nerve cells have to react with iron in solution very soon after burial if we are to preserve the neural ground pattern. Whatever the answers to such questions, soft tissue preservation is a clear pointer to fossilisation in a geological instant. Geologists (and others) are recognising that the principle of uniformitarianism promoted by Charles Lyell is a poor tool for interpreting the rock record, for many geological processes are abrupt and not gradual. Nevertheless, Lyell's legacy lives on in Darwinian evolution, where gradualism reigns supreme. Most Darwinians continue to stumble over the Cambrian Explosion and continue to predict that an extensive Precambrian fossil record will emerge with continued research. However, the fossil record that we do have, especially probed in detail as outlined in this blog, means that scenarios of "climbing Mount Improbable" savours more of a vivid imagination unconstrained by evidence. To understand why uniformitarianism is inappropriate for grappling with the Cambrian Explosion, go here. For a paradigm-shifting treatment of this whole issue, go here.
Chelicerate neural ground pattern in a Cambrian great appendage arthropod
Gengo Tanaka, Xianguang Hou, Xiaoya Ma, Gregory D. Edgecombe & Nicholas J. Strausfeld
Nature, 502, 364-367 (17 October 2013) | doi:10.1038/nature12520 (pdf here)
Preservation of neural tissue in early Cambrian arthropods has recently been demonstrated, to a degree that segmental structures of the head can be associated with individual brain neuromeres. This association provides novel data for addressing long-standing controversies about the segmental identities of specialized head appendages in fossil taxa. Here we document neuroanatomy in the head and trunk of a "great appendage" arthropod, Alalcomenaeus sp., from the Chengjiang biota, southwest China, providing the most complete neuroanatomical profile known from a Cambrian animal. Micro-computed tomography reveals a configuration of one optic neuropil separate from a protocerebrum contiguous with four head ganglia, succeeded by eight contiguous ganglia in an eleven-segment trunk. Arrangements of optic neuropils, the brain and ganglia correspond most closely to the nervous system of Chelicerata of all extant arthropods, supporting the assignment of "great appendage" arthropods to the chelicerate total group. The position of the deutocerebral neuromere aligns with the insertion of the great appendage, indicating its deutocerebral innervation and corroborating a homology between the "great appendage" and chelicera indicated by morphological similarities. Alalcomenaeus and Fuxianhuia protensa demonstrate that the two main configurations of the brain observed in modern arthropods, those of Chelicerata and Mandibulata, respectively, had evolved by the early Cambrian.
Chow, D. Ancient "Mega-Clawed" Creature Had Brain Like a Spider's, Scientific American (21 October 2013)
The steady flow of publications considering the way scientists interacted with the administration of the Nazi regime in Germany reveals some interesting cross-currents. It is well known that scientists who were out of step with the regime, particularly Jewish scientists, either emigrated (like Einstein) or ended up collaborating. Very few found it possible to operate independently of their political masters. Medical scientists have been previously considered in this blog (2008 - here), anatomists (2010 - here) and physicists have been the subject of a book-length study (2012 - here). For those tracing the ideological roots of the Nazi movement, one essential ingredient appears to be Social Darwinism: the application of Darwinian mechanisms to human society to understand change and to inform policy. However, there are some historians who demur, and say that Hitler was not a Darwinian. Chief among these is Robert Richards, whose new book is about to be published: "Was Hitler a Darwinian?" by University of Chicago Press. This divergence of thinking is actually significant in itself and worthy of our attention, especially as we approach the 70th anniversary of the ending of WWII. It is important to know what motivated the Nazis and it is important to reflect on the way the Nazis used science and politicized education - for they were world leaders in both.
Hitler's evolutionary ethic underlay or influenced almost every major feature of Nazi policy (source here)
The paper that addresses these issues directly is by Richard Weikart. He identifies six points of discussion and develops a multi-faceted argument that we cannot understand Nazi policy without recognizing the backdrop of Social Darwinism.
"While examining these lines of evidence, I will highlight the ways that Nazi racial thought was shaped by Darwinism (defined as biological evolution through the process of natural selection). [snip] These six points - derived from the view that humans and human races evolved and are still evolving through the Darwinian mechanism of natural selection - profoundly impacted Nazi policy. They formed the backdrop for eugenics, killing the disabled, the quest for "living space," and racial extermination." (p.538)
We cannot follow all issues covered in the paper, but will select some key topics that inform the conclusions. It is important to recognise that the Nazis saw themselves as mainstream thinkers - in their own eyes they were not a lunatic fringe! This needs to be understood when their thinking about the superiority of their own race is considered.
"[E]ven today some scholars are still loathe to entertain the idea that key elements of Nazi ideology could have been in harmony with the thinking of leading German scientists. Indeed the Nazi embrace of Darwinism in their racial ideology demonstrates the influence of science on Nazi ideology. Nazi racial ideology was largely consistent with the scholarship on race taught at German universities. This makes even clearer why so many German anthropologists and biologists supported Nazi racism - they were already committed to it before the Nazis came to power." (p.539)
It is also important not to think that this is a single issue discussion, and other factors are not relevant. The Nazi worldview has numerous elements, and we must not make the mistake of setting up a polarised straw-man analysis.
"I need to stress from the outset, however, that Nazi racial ideology was not derived exclusively from Darwinism or evolutionary biology. Gobineau - who wrote before Darwin published Origin of Species - contributed the idea that the Aryan race was superior to all other races. He also claimed that racial mixing produced deleterious effects, leading many racial thinkers, including the Nazis, to oppose miscegenation. Hatred of the Jews had a long history predating Darwin and has nothing to do with Darwinism. Also, Mendelian genetics played a role in debates over racial ideology - especially about policy relating to miscegenation - within the Nazi regime. However, in the decades preceding Hitler?s rise to power, many German racial theorists had synthesized Gobineau, Mendel, and antisemitism with social Darwinism. Nazi racial theory generally embraced this synthesis." (p.540)
In Hitler's writings, he makes it clear that racial mixing is not a good idea, because it violates evolutionary principles. His arguments invoke the concepts of selection, fitness, the struggle for survival which are all drawn from Darwinism.
"In the struggle for daily bread all those who are weak and sickly or less determined succumb, while the struggle of the males for the female grants the right or opportunity to propagate only to the healthiest. And struggle is always a means for improving a species' health and power of resistance and, therefore, a cause of its higher evolution." (p.541)
The Nazi regime sought to influence young people via educational programmes and youth movements. The curriculum made connections between what was taught and its social and political implications. Darwinism was explicit, and the textbooks followed suit.
"In 1938 the Ministry of Education published an official curriculum handbook for the schools. This handbook mandated teaching evolution, including the evolution of human races, which evolved through "selection and elimination." It stipulated, "The student must accept as something self-evident this most essential and most important natural law of elimination [of unfit] together with evolution and reproduction." In the fifth class, teachers were instructed to teach about the "emergence of the primitive human races (in connection with the evolution of animals)." In the eighth class, students were to be taught evolution even more extensively, including lessons on "Lamarckism and Darwinism and their worldview and political implications," as well as the "origin and evolution of humanity and its races," which included segments on "prehistoric humanity and its races" and "contemporary human races in view of evolutionary history." (p.542)
Weikart continues by looking at the Nazi leaders in academia and in political life, and in the racial propaganda literature they produced. One of the training pamphlets he quotes gives a clear overview of the message people were expected to absorb and which was reinforced by all the leading German scientists of the day..
"The opening pages explained that the central concepts underlying racial ideology are hard heredity and racial inequality. Then it claimed that racial inequality has come about because evolution proceeds by struggle. Different races simply do not evolve at the same pace, so they are at different levels. The authors then asserted that the three main human races - European, Mongolian, and Negro - were subspecies that branched off from a common ancestor about 100,000 years ago. They argued that races evolved through selection and elimination, and the Nordic race became superior because it had to struggle in especially harsh conditions. Throughout this pamphlet the terms "higher evolution," "struggle for existence," and selection are core concepts that occur repeatedly." (p.550)
The conclusions appear to be compelling. Those who are seeking to draw a line between Darwinism and the Nazi worldview have a hopeless task. This is how Weikart summarises his findings:
"Nazi racial ideology - and the many policies based on it - were profoundly shaped by a Darwinian understanding of humanity. Certainly many non-Darwinian elements were synthesized with Darwinism: Aryan supremacy, antimiscegenation, antisemitism, and many more. Nonetheless, Nazi racial ideology integrated all these factors into a worldview that stressed the transmutation of species, the evolutionary formation of the human races, the need for advancing human evolution, the inevitability of the human struggle for existence, and the need to gain Lebensraum to succeed in the evolutionary struggle." (p.552)
This is not an issue without relevance for societies today. Germany in the 1930s was no cultural backwater. They were confident they were building a worldview on rigorous science, affirmed by scholars across the world as well as in their own country. However, this worldview shaped the values held by the people: on ethics, on the worth of human life, and on their aspirations. There are people today who are seeking to build a worldview on evolutionary concepts. They are seeking to influence the educational processes in their own countries, and are creating a culture where dissent is treated as a betrayal of science. Their counsel is wide open to disasters similar to those faced by the Third Reich. We all need to review our personal worldview and to have answers for questions like: What is truth? What is ethical? Who is my brother? What is the worth of human life? What is worth struggling for?
The Role of Darwinism in Nazi Racial Thought
German Studies Review, 36(3), (October 2013): 537-556 (pdf here)
Abstract: Historians disagree about whether Nazis embraced Darwinian evolution. By examining Hitler's ideology, the official biology curriculum, the writings of Nazi anthropologists, and Nazi periodicals, we find that Nazi racial theorists did indeed embrace human and racial evolution. They not only taught that humans had evolved from primates, but they believed the Aryan or Nordic race had evolved to a higher level than other races because of the harsh climatic conditions that influenced natural selection. They also claimed that Darwinism underpinned specific elements of Nazi racial ideology, including racial inequality, the necessity of the racial struggle for existence, and collectivism.
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