Reorientation Gallery

  • Mount St Helens deposit - Credit: Chris Ashcroft

Deep Time

2018-08-30T13:49:49+00:00Categories: Reorientation Gallery|

The idea of deep geological time emerges in the late eighteenth century. James Hutton, a Scottish doctor and farmer, developed a theory of soil renewal which involved a continuous cycle of erosion, rock formation and mountain building in order that the land would be replenished and maintained fit for purpose. In support of this he recorded a number of sites in Scotland where there was a buried erosion surface separating two rock strata of different ages. These are known as unconformities. Hutton discovered an angular unconformity at Jedburgh in 1787 which provided him with what he “had been long looking for in vain” to demonstrated his theory of soil renewal with the vertical strata separated from the horizontal beds by a conglomerate layer which included eroded rocks from the lower beds. In interpreting these Hutton concluded, “that we find no vestige of a beginning, no prospect of an end.” Uniformitarianism It was from this that Charles Lyell subsequently developed the principle of uniformitarianism, (sometimes known as actualism or gradualism) as a basis for interpreting the geological record. This assumed that the conditions and processes of today had been consistent throughout time and therefore long periods of time were necessary to explain the formation of the rocks. This extensive timescale for earth history provided the backcloth for Darwin’s theory of evolution. The Siccar Point promontory Another of the sites which influenced Hutton was Siccar Point, Cockburnspath in Scotland on which he commented “What clearer evidence could we have had of the different formation of these rocks, and of the long interval which separated their formation” 1 It is considered the type site of the uniformitarian school of thought and a cast of the site was made for display in the American Museum of Natural History in 1998. More recent views on the site suggest that sandstone beds were deposited rapidly, as the British Geological Survey regional guide has indicated: "The Upper Old Red Sandstone sediments appear to have been deposited over a slowly-subsiding area subjected to periodic flooding and desiccation. The local basal conglomerates represent the products of torrential stream erosion but as subsidence and deposition went on this early phase gave place to one of shallow continental basins" 2 Examination of the rocks at Siccar Point reveal that the vertically bedded rocks have eroded extensively in recent times where exposed to the weather. It is reasonable to suppose that they would also show signs of considerable weathering in antiquity if there had been “a long interval” separating the formation of these rocks. The absence of such evidence further supports the view that they were deposited over a short period of time. Catastrophism A reworking of the evidence therefore questions Hutton’s belief that “a long interval” had elapsed between the formation of these rocks. Today the principle of uniformitarianism has been superseded with that of catastrophism linked with tectonic activity. As Stephen Jay Gould has observed “The geologic record does seem to require catastrophes: rocks are fractured and contorted; whole faunas are wiped out”.3 The impact of recent natural disasters gives a slight insight into the effects that a major catastrophe would have had on the world around us. The eruption of the volcanoes at St Helens, USA in 1980 and at Eyjafjallajökull, Iceland in 2010 give an indication of the impact a single volcanic eruption can have. The St Helens eruption flattened vegetation and buildings over some 230 square miles (600 km²) and about 540 million tons of ash fell over an area of more than 22,000 square miles (60,000 km²).The flow of debris from the crater formed a 25 foot (7.6 m) layered deposit. Similarly, the 2011 earthquake off the coast of Japan and that in the Indian Ocean in 2004 resulted in tsunami waves up to 33 feet (10 meters) high. The 2004 disaster resulted in some 200,000 deaths in countries bordering the Indian Ocean. The tsunami deposited sediment in many parts of the region, a single wave in Sumatra depositing 45 cm (18 inches) of sand which in section can be seen to be graded upward from coarse to fine. The move towards catastrophic interpretations of the geological record raises fundamental questions about the timescale required for these events to have taken place.

  • A blind and a sighted Cavefish - Credit: Florida Atlantic University - Alex Keene

What is biological evolution?

2019-12-30T12:27:12+00:00Categories: Reorientation Gallery|

What is biological evolution? Darwin described it as “descent with modification”. It is regarded as the process whereby heritable traits change over successive generations. Micro-evolution The mechanisms that produce such change are considered to be natural selection and genetic variation. Natural selection can result from such factors as changing environmental conditions or the choice of sexual partners. Artificial selection involving the purposeful breeding of species is common practice. Genetic variation can arise through interbreeding, migration and population bottlenecks, for example. Together they facilitate adaptations which may be beneficial or detrimental and can even led to extinction. Genetic variation can readily be observed among individuals within species. This is sometimes described as micro-evolution. Recent research involving hybridization between two different populations of blind cavefish in Mexico has resulted in offspring with a restored visual function. Dormant genetic information had been re-activated and the structures of the eye and the connections to the brain to provide sight had been restored.1 While the biological definition of a species may be taken as a group of individuals capable of interbreeding and therefore isolated reproductively from other groups, the same definition cannot be verified with dead or fossil material. In the historical sciences therefore there is a greater reliance on morphology which has been the basis for classification since the eighteenth century. There is much evidence to support speciation, the development of new species from existing ones among living organisms. Speciation can be well illustrated among the cichlid fish of Lakes Tanganyika and Malawi where a remarkable degree of convergence both in colour patterns and in trophic morphologies can be shown although from two different lakes.2 Darwin demonstrated this among the finches of the Galápagos Islands. The term macro-evolution is sometimes used in connection with speciation but as it is used variously, and to include common descent, is not used here. Neo-Darwinian evolution Darwinian evolution, and contemporary developments of it, assert that current living organisms arose from a universal common ancestor through the mechanisms observed in speciation. But fossil evidence to support this has not been found. In the absence of such evidence, evolutionary trees are constructed based on hypothetical relationships among organisms. These assume that organisms are related by descent to a common ancestor and that their characteristics change over time. Based on an evolutionary paradigm, it is intended to demonstrate common ancestry through the shared characteristics of organisms. This is known as cladistics and may be presented graphically as a cladogram.3 There remains, however, the fundamental issue that the information contained in DNA to provide instructions to support life and determine the nature of the organism concerned, are not a matter of chance and necessity.4 They cannot be generated from material or energy. It should be noted also that despite the popular view, evolutionary theory contributes little experimental biology.5

  • Homology animal forearms - Credit: Волков Владислав Петрович

A universal common ancestor

2018-08-17T13:07:35+00:00Categories: Reorientation Gallery|

Darwin believed that life evolved from simple to complex life forms. He said: “On the view that each species has been independently created, I can see no explanation of this great fact in the classification of all organic beings; but, to the best of my judgment, it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram.” 1 Homology Two important principles contributed to Darwin’s theory. The first was homology, the similarity of body parts in two or more species. Darwin saw the similarities in structure and position among very different animals, such as the forearms shown here, being the result of natural selection working on shared ancestral patterns. Descent with modification was inferred from this. Superposition The second principle was superposition. With the oldest rocks at the base and the most recent at the top, it was predicted that biological evolution would therefore be demonstrated as a succession from the oldest to the youngest geological strata. The idea of certain types of fossil being identified with different rock layers was already established in Darwin's day and forms an aspect of the geological column today. Such a succession has not been realised, as Stephen J Gould states: “The absence of fossil evidence for intermediary stages between major transitions in organic design, indeed our inability, even in our imagination, to construct functional intermediates in many cases, has been a persistent and nagging problem for gradualistic accounts of evolution.” 2 He developed the theory of punctuated equilibria in response to this. Another commentator remarked: “These gaps might be due to failure in fossilization, or to mistakes in the genealogy, or to wrongly identified fossils; or they could be (and have been) taken to show that the theory of evolution is wrong.” 3 Molecular biology With the development of molecular biology additional evidence has been invoked to demonstrate evolution. However, Carl Woese, who pioneered the construction of molecular phylogenetic trees in support of evolutionary theory in 1990, wrote eight years later that “the universal ancestor is not an entity, not a thing” and concluded that “the universal phylogenetic tree, therefore, is not an organismal tree at its base” 4 W Ford Doolittle, another molecular biologist, argued that “new hypotheses, having final forms we cannot yet guess, are called for”, 5representing the tree of life as a bush.6 In 2007 he commented “there is no independent evidence that the natural order is an inclusive hierarchy”.7 The prevailing view today is that the process of life does not lend itself to patterns expressed by simple tree-forms. A reticulated structure, such as is now proposed, and the lack of fossil evidence throw into question the theory of a universal common ancestor.

  • Electron microscopy of a sample of red rain - Credit: CCAB, Cardiff University,after N.C. Wickramasinghe et al.

Origin of Life

2020-02-04T15:07:40+00:00Categories: Reorientation Gallery|

Most research into the origin of life is based on one of two theories: Abiogenesis, the assumed generation of life from non-living matter, or Panspermia (sometimes known as Exogenesis) based on the idea that life reached earth from the cosmos. Abiogenesis A number of experiments have been conducted in varying conditions considered to simulate primeval conditions. Best known are those undertaken in the laboratory by Miller and Urey in 1953 which produced amino acids in an electrically charged atmosphere but no life. More recent work using oxidation inhibitors has greatly increased the amino acid yield but has not approached the produced life itself.1 NASA-funded research, undertaken for over 20 years, has included field experiments in pools of heated and sterile water associated with volcanoes in the Kamchatka region of eastern Russia and at the Lassan Volcanic Park in California. Here a "pre-biotic" soup containing the building blocks of proteins and DNA with fatty acids are being poured into a volcanic pool in Kamchatka but they failed to interact, becoming bound with the clay of the site instead. From this work it has been concluded that geothermal springs and similar extreme environments do not favour membrane formation, seen as a prerequisite to the development of cellular life. An alternative suggestion had been that rock cavities at hydrothermal vents might have provided the structure in which life emerged. 2 Panspermia The idea that life reached earth from the cosmos is known as panspermia or exogenesis. Mars is considered a prime source as it is similar to Earth with systems of air, water, ice, and geology. Evidence of water, a necessary prerequisite for life, has been found at Melas Chasma on Mars.where water-based processes have created fans of debris as well as the channels through which water and sediment flowed.3 NASA’s Mars Exploration Program seeks to understand whether Mars was or can be, a habitable world. Meteorites have also been considered a possible source to indicate the existence of life elsewhere in the universe. Examination of meteorites for evidence of fossils or other signs of life however has been inconclusive. In this work the possibility of the contamination of our solar system from the abundance of life on earth, either as a result of meteorite impacts or through transmission by spacecraft, has to be considered. The meteorite which fell near Murchison, Australia in 1969 contains complex organic molecules such as amino acids but scientists are divided as to whether they result from contamination or not.4 The meteorite from Allan Hills, Antarctica (ALH 84001) revealed structures which were considered for a time to be fossil evidence from Mars but this is now largely discounted 5 although the original researchers still consider that the most plausible explanation is that they are life remains.6 The discovery of microscopic red cells in rain in Kerala, Southern India in 2001 led to a suggestion that they might represent extraterrestrial life from space. High resolution electron microscopy revealed internal structures as well as evidence of a replication cycle and have now been identified as Trentepohlia algae spores. 7 Despite laboratory and field simulations it has not been possible to generate life; neither has evidence of life been found elsewhere as a result of NASA’s space programme or the examination of meteorites.

  • Galaxy NGC 4319 and quasar Markarian 205 have different redshifts. - Credit: NASA/Hubble Space Telescope

The Big Bang

2018-08-23T22:45:08+00:00Categories: Reorientation Gallery|

The "big bang" theory assumes that a balloon-like inflation of a single source of energy and matter, rather than an explosion at a point in space, led to the formation of the universe. It predicts that the universe is still expanding and also that it should contain the residual radiation from the heat of the "big bang". An expanding universe? An expanding universe cannot be observed directly. However, if galaxies are moving away from each other, the light from them would be stretched. This would have the effect of increasing the wavelength of emitted light towards the red end of the spectrum, known as redshift. Quasars show a very high redshift and are, therefore, considered very distant and much earlier in the history of the universe. Other studies, however, suggest that the large redshifts of quasars result from the speed of their ejection from a host galaxy and therefore question the use of redshifts to support the "big bang" and an expanding universe.1 An example of evidence used to support this view is the relationship of galaxy NGC 4319 to the quasar Markarian 205 which have markedly different reshifts. A false colour image of these suggests that they are connected by a "luminous bridge" and therefore redshifts do not support the "big bang".2 The recent discovery of a quasar with a much higher redshift than the nearby spiral galaxy NGC 7319, provides additional supporting evidence 3. Residual radiation? The prediction that the universe should contain residual radiation from the heat of the "big bang" received a boost when the cosmic microwave background (CMB) was discovered in 1965. The US National Aeronautics and Space Administration (NASA) has been examining this and other issues relating to the origin of the universe with its Cosmic Background Explorer spacecraft (COBE) and its successor, the Wilkinson Microwave Anisotropy Probe (WMAP). Measurements by the COBE satellite revealed a uniformity of temperature inconsistent with an event that had made stars and galaxies. The variations in temperature were insufficient to meet the prediction. Although the "big bang" theory was modified in the light of these findings, interpretation of measurements from the WMAP satellite has led scientists to suggest that the radiation does not relate to the origin of the universe.4 Recently other scientists, reworking the WMAP data, suggest that the CMB ripples are even smaller than estimated before, and question whether hypothetical dark matter and dark energy exist at all.5 Other work involved the examination of some 31 clusters of galaxies but the majority failed to cast a shadow on the cosmic microwave background, so raising doubt about its origin at the furthest edges of the universe.6 It has also been shown that luminosity remains constant which favours a static rather than an expanding universe. This in turn raises questions about distance and dating in the universe.7 Despite the extensive body of information collected by NASA and interpreted by its scientists in support of the “big bang”, and the assumptions behind some of the experiments at the CERN Large Hadron Collider, there is growing doubt about the theory. In 2004 a letter in the New Scientist, stated that ‘… the big bang theory can boast of no quantitative predictions that have subsequently been validated by observation. Today … the dominance of the big bang within the field has become self-sustaining, irrespective of the scientific validity of the theory’ 8. Two international conferences have since been held on this crisis in cosmology.9

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