Science Literature

Harvestmen are said to be the third most-diverse arachnid order, and few will be unaware of these long-legged creepy-crawlies living somewhere near to our own homes. They belong to the order Opiliones and although the fossil record is understandably sparse (the exoskeleton is poorly mineralised), the fossil record is informative. Some of the earliest insects known are in intimate association with plant material - preserved in the Rhynie Chert. "Devonian (~410 Myr) harvestman fossils from the Rhynie Chert, while incomplete, preserve a three-dimensional internal anatomy suggestive of an essentially modern body plan." The opportunity has come to check out this suggestion, using high-resolution X-ray micro-tomography to examine specimens preserved in siderite nodules. The X-ray scans allow parallel slice images of the fossils to be recorded, from which three-dimensional, virtual models of the organisms are assembled.

"The international team, led by scientists at Imperial College London, took over 3000 X-rays of the harvestmen fossils from France, dating to the Carboniferous Period [. . .]
The scans were edited using computer software to produce highly detailed and accurate 3D models. They reveal 2 new species of ancient harvestmen, Macroglyon cronos and Ameticos scolos, which, unlike most land animals from this time, had bodies very similar to their modern relatives living today."

The probable appearance in life of A. scolos gen. et sp. nov. (above) and M. cronus gen. et sp. nov. (below). Scale bar, 5 mm. (Source here)

The most notable finding is that these insects are essentially modern. They belong to two identifiable suborders. The research paper provides a cladogram with the ancient harvestmen alongside modern forms: "comparable taxa of the modern Eupnoi and Dyspnoi". Dr Russell Garwood, currently based in the computed tomography lab at the Natural History Museum in London, is quoted as saying:

"It is absolutely remarkable how little harvestmen have changed in appearance since before the dinosaurs. If you went out into the garden and found one of these creatures today it would be like holding a little bit of prehistory in your hands. We can't yet be sure why harvestmen appear so modern when most land animals, including their cousins such as scorpions, were in such a primitive form at the time. It may be because they evolved early to be good at what they do, and their bodies did not need to change any further."

There is a problem with much of the terminology being used to describe fossils. I am thinking of words like: "primitive" and "modern" (also "stem" and "crown"). Much of this terminology is driven by a Darwinian perspective - a theoretical model of what the fossil record ought to be like. Cladism has imbibed this mindset, because it infers a lineage of organisms that can be reconstructed by the appearance of novel structures. Unfortunately, the fossil record is proving to be less and less Darwinian as we examine the details. We have modern body plans where there should be primitive body plans. We have primitive 'relict' species living on when they should have become extinct. We have to invoke 'convergence' to explain similar structures that do not fit the linear model. (But convergence is ubiquitous - here). Why should we live with such an unwieldy interpretative framework?

Most significant is the pattern of animal and plant radiation that we find in the fossil record. Darwin predicted a branching bush or tree - but this is not what we find! The Cambrian Explosion is the best rebuttal of this, for it demonstrates an initial burst of diversification and speciation followed by relative stasis (See here, here and here). This pattern of diversification suggests caution about using the word "primitive" or "modern" in an evolutionary sense. Are the characters under investigation part of the early diversification of an order or a Family? If the answer is 'yes', then we should be very cautious about placing an evolutionary interpretation on it - to say something is primitive then becomes little more than saying that it became extinct. This is one reason for documenting cases of stasis in the fossil record - there is far more evidence of modernity in the fossil record than is currently acknowledged by Darwinists. (For some recent blogs, try one, two, three, four and five).

Anatomically modern Carboniferous harvestmen demonstrate early cladogenesis and stasis in Opiliones
Russell J. Garwood, Jason A. Dunlop, Gonzalo Giribet, Mark D. Sutton
Nature Communications, 23 August 2011, 2, Article number: 444 | doi:10.1038/ncomms1458 (pdf here.)

Abstract: Harvestmen, the third most-diverse arachnid order, are an ancient group found on all continental landmasses, except Antarctica. However, a terrestrial mode of life and leathery, poorly mineralized exoskeleton makes preservation unlikely, and their fossil record is limited. The few Palaeozoic species discovered to date appear surprisingly modern, but are too poorly preserved to allow unequivocal taxonomic placement. Here, we use high-resolution X-ray micro-tomography to describe two new harvestmen from the Carboniferous (~305 Myr) of France. The resulting computer models allow the first phylogenetic analysis of any Palaeozoic Opiliones, explicitly resolving both specimens as members of different extant lineages, and providing corroboration for molecular estimates of an early Palaeozoic radiation within the order. Furthermore, remarkable similarities between these fossils and extant harvestmen implies extensive morphological stasis in the order. Compared with other arachnids - and terrestrial arthropods generally - harvestmen are amongst the first groups to evolve fully modern body plans.

See also:

Ancient harvestmen in 3D reveals early evolution, Natural History Museum Press Release (23 August 2011)

Crop circles are patterns formed by the flattening of crops. They have been reported for hundreds of years and are reputed to appear around the world at a rate of one every evening. They only form during the night. Crop circles have always had something extraordinary about them, stimulating "mowing devil" explanations and also the influence of aliens. What are we to make of these phenomena? This is a good opportunity to discuss how a scientific mind approaches the problems and the relevance of design inferences to science. In a recent feature article on crop circles, Richard Taylor writes:

"Speculation over the origin of crop circles has raged since they were first reported in England in the 1600s, with rolling hedgehogs, urinating cattle, romping romantic couples and the actions of a "mowing devil" all offered as early explanations. In 1678 a series of circles in Hertfordshire was attributed to the devil because the manufacture appeared to be beyond human capabilities. According to a report in a 1678 issue of News Out of Hartfordshire, the devil "placed every straw with an exactness that would have taken up above an age for any man to perform what he [the devil] did that one night"."

A field of fractals. On 29 July 1996 this crop circle appeared on Windmill Hill near Avebury, UK. Its design is based on an equation formulated by Gaston Julia in 1918. A similar "Triple Julia" fractal design was also used in a crop circle in Switzerland last year. (Courtesy: Steve Alexander. Source here)

Apparently, the first scientific analysis of crop circles invoked "Law" as an explanation. This was in 1686, by a British scientist called Robert Plot. Linear wind surges and circular eddies were considered to account for the observations. Natural phenomena continue to be considered. More recently, a prominent advocate has been Terence Meaden, a Canadian meteorologist and physicist.

"In 1980 Meaden [. . .] propos[ed] that the curvature of hillsides in southern England affected the local airflow, allowing whirlwinds to stabilize their positions long enough to define circles in the crop fields."

Even Professor Stephen Hawking has given some credence to weather-related causation:

"When a spate of circles appeared in the countryside near his Cambridge home in 1991, Hawking told a local newspaper that "crop circles are either hoaxes or formed by vortex movement of air"."

"Chance" has not been favoured as an explanation of the data. Rolling hedgehogs and urinating cattle leave their marks, but nothing like crop circles! Analysts have been impressed by the specified complexity of the flattened crops. The choice for them has always been either "Law" or "Design".

Whilst many suspected human activity, people did not own-up to making crop circles. If this is the explanation, the perpetrators have kept remarkably silent about their accomplishments! There were two schools of thought: one group concentrated on humans, whereas the other group looked for aliens and UFOs.

"In the waning decades of the 20th century, this conclusion ignited a heated aliens-versus-humans debate, with "UFOlogists" looking to outer space for the circles' artistic creators, while "cereologists" concentrated on hunting for terrestrial hoaxers. This debate was complicated by the fact that the creators (whoever they were) were clearly science-savvy. In particular, one formation that appeared next to Chilbolton Observatory in Hampshire appeared to be a reply to a "search for extraterrestrial intelligence" signal beamed into space 30 years earlier."

However, this discourse changed in 1991, when "two unassuming men in their sixties declared that they had been creating crop circles for more than 25 years." At last, the silence had been broken! These two could not be responsible for all the crop circles made in this period, but they did confess to making 250 of them (20% of the total in England).

"Their hobby had begun one summer evening in the mid-1970s, when artist Douglas Bower recounted a story to his friend David Chorley about an Australian farmer who had reported a UFO rising into the sky and leaving behind a circular "saucer nest". As Bower and Chorley strolled home from the pub through the English countryside, they created their first imitation nest."

According to Taylor, the Bower & Chorley announcement triggered a revival in construction of crop circles. The practice went international, and was characterised by sophistication. Although England still boasts 50% of each year's crop circles, they occur in Europe, North and South America, Russia, Australia, Japan and India.

"Artists who readily admit to having made crop circles in the past say they do not know who is responsible for all of today's masterworks. This is partly because many crop-circle artists have followed the conventions established by their predecessors: creating their pictographs anonymously, under cover of darkness, and leaving the scene free of human traces. But although the new artists are traditionalists in this sense, in other respects their craft has moved on considerably. Today's artists, for example, have access to computers, GPS equipment and lasers to help map out their patterns."

The rise of high technology crop circle creation has been noted in the media, and an example is an article by Nick Collins in the Daily Telegraph. What some regard as unexpected mathematical sophistication in human hoaxers, others continue to regard as the signatures of alien minds.

"Today's crop-circle designs are more complex than ever, featuring up to 2000 individual shapes arranged using intricate construction lines that are invisible to the casual observer. The increase in available computing power has also meant that iterative equations are now frequently used to generate fractal shapes such as the Triple Julia design, which reappeared in Switzerland last year. Other famous fractal icons such as the Mandelbrot set, the Julia set and the Koch snowflake have also popped up regularly in crop fields since 1991."

There are still mysteries about how these patterns are made, how secrecy is maintained, and how so much is done in the available time. These puzzles continue to engage the interest of enthusiasts. Taylor writes: "Crop-circle artists are not going to give up their secrets easily." Interest in the alien explanation continues. Are we dealing here with "The most science-oriented art movement in history"? - as Taylor suggests. Or are we witnessing tangible signs of the presence of aliens? As has been pointed out many times before, design inferences allow us to infer intelligent causation, but the identity of an intelligent agent is a separate issue which may or may not be easy to resolve. As this summer period is a time for rest and relaxation for many of us, we have an opportunity to reflect further on these questions - and hopefully reach some answers.

Coming soon to a field near you
Richard Taylor
Physics World, August 2011, 26-31. (pdf here)

Serious studies of crop circles have long been hampered by conspiracy theories and the secretive nature of circle-makers - plus scientists' reluctance to engage with a "fringe" topic. But, as Richard Taylor argues, discovering how circle artists create their most complex patterns could have implications for biophysics

In June 2005, biophysicist David Deamer and colleagues visited a pool of water heated by volcanic activity on Russia's Kamchatka Peninsula. The scientists were under the impression that the water was sterile and that volcanism had erased all signs of life. "Darwin proposed that life started in 'a warm little pond'. . . . We are testing his theory in 'a hot little puddle'," Deamer related at a meeting of the Royal Society in London in February 2006. The group poured a "primordial soup" of proteins, DNA, and cell membranes into the pool and waited to see what would happen.

"When the scientists sampled the water after a few hours, they were surprised to find that most of the added material had disappeared. Tests revealed that the missing ingredients were bound to the clay that lined the tiny pond. The molecules "are nailed down, so they can't interact," Deamer says. As a result, hot volcanic pools may be unlikely spots for the first assembly of life's little bits, says Deamer." (source here)

David Deamer pours a "prebiotic soup" of chemicals into a volcanic pool in Kamchatka, Russia, to test a hypothesis about the origins of life. (Photo by Tony Hoffman, source here)

With this anecdote, Robert Shapiro commences his review of Deamer's latest book: First Life: Discovering the Connections between Stars, Cells, and How Life Began. Actually, Deamer refers also to the incident in the book and describes it as a "reality check". It taught him that natural systems are quite different from the laboratory and although numerous papers have been published on abiogenesis in the lab, the authors have failed to grapple with the principle that "we cannot translate lab results to natural settings".

"Because we can get reactions to work in the controlled conditions of a laboratory, he cautions, it does not follow that similar ones occurred on prebiotic Earth. We might overlook something that becomes apparent when we try to reproduce the reactions in a natural setting. This provocative insight explains why the origin-of-life field has been short on progress over the past half century, whereas molecular biology has flourished."

The dominant contemporary theoretical approach to abiogenesis is known as the RNA World. The basic idea is that an RNA strand appeared spontaneously in the Archaean era of the early Earth. This RNA molecule had the ability to replicate itself. Shapiro says: "The advantage of this idea is that the formation of just one polymer would be all that was needed to get life started. The disadvantage is that such an event would be staggeringly improbable." There are chemical problems just getting the RNA strand, but added to this are the problems of achieving replication. This is why some scientists have chosen to opt out of the RNA World paradigm and attempt to develop a rather different approach.

"Nucleotides, for example, are not encountered in nature beyond organisms or laboratory synthesis. To construct RNA, high concentrations of four select nucleotides would be needed in the same location, with others being excluded. If this is the prerequisite for life, then it is an unusual phenomenon, rare in the Universe. As an alternative, other scientists (myself included) have suggested that life started without the presence of polymers; that instead, heredity and catalysis began with monomers."

So, Deamer's book plows a new furrow. He considers the cell has to come first, so looks for ways of constructing a cell-like compartment. He does not like the deep-oceanic vent approach to doing this, because he considers hot seawater to be a liability, not an asset. Inside this cell-like structure, he seeks to form a self-replicating polymer.

"Deamer's thesis diverges from the standard RNA-world concept. He focuses not on the generation of a naked RNA-like polymer, but on the formation of a simple cell-like compartment, or vesicle. Modern cells are enclosed by a complex fatty membrane, which prevents leakage. Vesicles with similar properties have been formed in the lab from certain fatty acids. Deamer holds that the spontaneous formation of vesicles, into which RNA could be incorporated, was a crucial step in life's origin. Unfortunately, his theory retains the improbable generation of self-replicating polymers such as RNA."

That last comment from Shapiro reveals that he is not very impressed with Deamer's alternative proposal. But he also knows that a review is not the best platform to promote one's own approach. So the conclusion majors on a plea for more realism about the demerits of the RNA World and less deductive thinking about the nature of Archaean geochemistry.

"Nevertheless, Deamer's insight deflates the synthetic proofs put forward in numerous papers supporting the RNA world. He ends First Life by calling for the construction of a new set of biochemical simulators that match more closely the conditions on the early Earth. Unfortunately, the chemicals that he suggests for inclusion are drawn from modern biology, not from ancient geochemistry. We should let nature inform us, rather than pasting our ideas onto her."

This is good advice for all students of Earth history. There may be a consensus about the RNA World, but it is not a consensus based on evidence. The approach is supported by synthetic proofs drawn from unrealistic laboratory experiments, showing all the signs of a dogmatism that pastes its ideas on to nature. At our present state of understanding the issues, it is realistic only to acknowledge the tentativeness of all current theories of abiogenesis.

Astrobiology: Life's beginnings
Robert Shapiro
Nature, 476, 30-31, (04 August 2011) | doi:10.1038/476030a

Abstract: Robert Shapiro on a reminder that laboratory experiments don't always translate to nature.

Book reviewed: First Life: Discovering the Connections between Stars, Cells, and How Life Began, David Deamer, University of California Press: 2011. 288 pp. ISBN: 9780520258327

See also:

Luskin, C. Presto! The Origin of Life in Four Surprisingly Easy Steps, Evolution News & Views, August 8, 2011