In The Blink Of An Eye Read online

  Table of Contents

  Praise

  Title Page

  Dedication

  Table of Figures

  Epigraph

  Preface

  Chapter 1 - Evolution’s Big Bang

  Life as we know it

  Understanding the variety of life

  The Cambrian explosion in brief

  ‘The History of Life’ from the very beginning

  The Burgess quarries today

  A century of research

  Palaeontological gold

  The $64 million question

  The answers proposed

  Preview

  Chapter 2 - The Virtual Life of Fossils

  The youngest fossils

  Old bones, new science

  The active Earth

  Reconstructing ancient environments

  Palaeontology - the first forensic science

  Trace fossils

  Adding further flesh to the bones

  Palaeontology meets modern engineering

  Taking our tools to the Cambrian

  Chapter 3 - The Infusion of Light

  Before the Victorians

  Another Victorian curiosity

  Pigments

  Evolutionary interlude

  The purpose of pigments

  The officer’s hat, or the relevance of size and shape

  Structural colours

  Chapter 4 - When Darkness Descends

  Night-time on land

  The deep sea

  Caves

  Chapter 5 - Light, Time and Evolution

  Living fossils

  Diffraction gratings - a subject of physics

  A sudden flash of green light

  Bioluminescent seed-shrimps

  The global view - evolution of all notched seed-shrimps

  Natural diffraction gratings

  Australia’s upside-down flies

  From sound to light

  The list continues

  Chapter 6 - Colour in the Cambrian?

  Ammonites - multilayer reflectors and modifications

  The Messel beetles - original multilayer reflectors

  Fossils of the Burgess Shale - diffraction gratings

  Chapter 7 - The Making of a Sense

  Not to see

  To see

  Ancestral eyes

  Chapter 8 - The Killer Instinct

  Another thing about eyes

  Swords, shields and scars

  In the original line of fire

  Chapter 9 - The Solution

  Should we consider predation too?

  Armaments are ornaments

  The ‘Light Switch’ theory

  Life as we know it

  Why vision and not other senses?

  Near-final thoughts

  Chapter 10 - End of Story?

  A final word

  Index

  Copyright Page

  Table of Figures

  Figure 1.1 The division of life into categories of different levels, using the woodlouse Porcellio scaber as an example. There are thirty-eight phyla of multicelled animals.

  Figure 1.2 The geological timescale and epochs.

  Figure 1.3 An amoeba - a cell with a nucleus and organelles.

  Figure 1.4 Sections through representative bodies of different phyla showing simplified examples of internal body plans.

  Figure 1.5 The Ediacaran animals Tribrachidium, Mawsonites and Parvancorina.

  Figure 1.6 The Ediacaran animal Dickinsonia costata.

  Figure 1.7 Marrella from the Burgess Shale - fossil and three-dimensional reconstruction.

  Figure 1.8 Tow versions of the history of the animal phyla. From the first soft-bodied form, evolutionary branching is equivalent in both models. (A) indicates that both internal body plans and external parts diversified throughout this branching, and most theories on the cause of the Cambrian explosion have been based on this model. (B) is the correct model and properly identifies the Cambrian explosion - that it was the simultaneous evolution of external forms in all phyla.

  Figure 2.1 Butterworth’s 1920s illustration of Diplodocus walking, crocodile-style.

  Figure 2.2 Diagrammatic cross-section of a living nautilus (eye not shown) and photograph of a fossil ammonite (part of tube preserved near centre of shell).

  Figure 2.3 The footprints discovered in Greenland, made in both firm ground and sloppy mud.

  Figure 2.4 Palaeo-map of the world, at the time of the Burgess dynasty, showing the original location of the Burgess reef.

  Figure 3.1 Newton’s own drawing of his experimentum crucis. Unfortunately he lacked the artistic genius of Leonardo.

  Figure 3.2 Light rays affected by a thin film, such as a fly’s wing, in air. The film is shown in cross-section; the light-ray paths and wave profiles are illustrated as solid lines (incoming light) and dashed lines (reflected light).

  Figure 3.3 A cross-section through a liquid crystal (left), showing individual helical molecules, and its approximation as a stack of thin layers and effect on light (right). Reflected light rays are in phase when the layers are approximately a quarter of their wavelength in thickness.

  Figure 4.1 A twelfth-century fishing trap recovered from the River Thames.

  Figure 4.2 A typical scavenging isopod, amphipod and ostracod (seed-shrimp).

  Figure 4.3 Simplified schematic section through two of Earth’s plates, showing the submarine landscape between, including their line of separation.

  Figure 5.1 A notched lightweight seed-shrimp with one half of its shell removed to reveal its body and limbs inside (from Cannon, 1933, Discovery Reports). The arrow points to the halophores of the left first antenna.

  Figure 5.2 A diffraction grating splitting white light into a spectrum.

  Figure 5.3 Scanning electron micrograph of a diffraction grating of the ‘baked bean’ (Azygocypridina lowryi). Spacing between grooves is 0.6 microns. (Plate 15 in the colour section shows the iridescent effect of this structure.)

  Figure 5.4 Frame from a video recording of a pair of the notched seed-shrimp Skogsbergia species mating. The iridescent flash of the male is arrowed.

  Figure 5.5 Electron micrograph of a hair from Lobochesis longiseta, a bristle worm. The ridges are spaced about one micron apart, forming a diffraction grating that causes a spectral effect.

  Figure 6.1 Micrographs of the Burgess bristle worm Canadia at increasing magnification - from x10 to x1,500. The top picture shows the front half of the animal, the middle pictures show details of bristles. The bottom picture shows the surface of a bristle as removed from the rock matrix, revealing the remnants of a diffraction grating with a ridge spacing of 0.9 microns.

  Figure 7.1 Marginal sense organs of the jellyfish Paraphyllina intermedia and Aurelia aurita, showing different levels of complexity (particularly in their light detectors).

  Figure 7.2 The three types of simple eye - pinhole, mirror and camera-type - and their effect on light rays. Light receptors (retinas) are shaded. The mirror eye has an underlying mirror (dashed region) and the camera-type eye has a lens, both of which focus light to form clear images.

  Figure 7.3 Focusing of light rays (solid lines) by a graded lens (only three grades of material are shown). The dashed lines represent the paths induced by a standard lens of uniform material - the steeper angles of contact cause light to be bent more at the periphery. The core material of the graded lens, however, causes light to bend more than the material of the periphery layer, and so counteracts this angular discrepancy.

  Figure 7.4 Scanning electron micrograph of the head of a fly, showing compound eyes.

  Figure 7.5 Focusing mechanisms in the compound eyes of a) bees (apposition-type eye); b) moths and c) lobsters (supe
rposition-type eyes). Graded material in b) and mirrors in c) (shown from the side and from above) achieve focusing. (Modified from Land, 1981.)

  Figure 7.6 Anomalocaris and Waptia from the Burgess Shale. At around 7.5cm, Waptia is several times smaller than Anomalocaris.

  Figure 7.7 Micrographs of the heads of a living ‘mysid’ crustacean and Waptia from the Burgess Shale. Eyes show comparable internal architectures. Scale bars represent 2mm (top picture) and 0.5mm (bottom picture).

  Figure 7.8 Yohoia, Perspicaris, Nectocaris and Sarotrocercus - examples of Burgess animals with eyes.

  Figure 7.9 The tiny Cambrian arthropod Cambropachycope, with a single compound eye.

  Figure 7.10 The Cambrian arthropods Canadaspis laevigata and Fortiforceps foliosa from Chengjiang, China.

  Figure 7.11 The evolutionary tree of animals at the level of phyla (all those with representatives alive today are included; note that Choanoflagellata is not a true multicelled group). Asterisks mark the phyla with eyes (which are also numbered 1 to 6 as they appear in the text). Modified from a paper by Rouse and Fauchald.

  Figure 7.12 Haikouella lanceolata from Chengjiang - the earliest known chordate.

  Figure 7.13 Photographs of holochroal (above) and schizochroal (below) trilobite eyes.

  Figure 7.14 The intralensar bowl design in the lenses of some trilobites; light rays striking all parts of the lens are focused in the same plane. An identically shaped lens without the intralensar bowl is shown for comparison.

  Figure 7.15 Time ranges of genera within the seven families of trilobite, showing the occurrence of different kinds of eye (after Euan Clarkson, 1973). Note that the very first trilobites, living at the base of the Cambrian, bore (holochroal) eyes.

  Figure 7.16 Nilsson and Pelger’s predicted evolution of a camera-type eye, like that of a fish. The sequence begins with a flat patch of light-sensitive cells sandwiched between a transparent protective layer and a layer of dark pigment. A graded-index lens appears at stage 6. Reproduced from a 1994 paper by Nilsson and Pelger with permission from the authors.

  Figure 8.1 One of the original stereograms of 1838. Blur the picture to produce a fused image in the centre. The inner ring will appear nearer than the outer ring.

  Figure 8.2 The early Cambrian trilobite Fallotaspis typica showing eyes (shaded) positioned at the side of the head, although its sight is directed slightly forward.

  Figure 8.3 Odaraia and Sidneyia from the Burgess Shale.

  Figure 8.4 Naraoia, a Naraoid from the Burgess Shale.

  Figure 8.5 Photograph of a trilobite when rolled up - ‘head’ spines can be seen projecting from the body. When the trilobite is flat, as we usually view trilobites, these spines lie flush with the body.

  Figure 8.6 Pirania, Micromitra and Haplophrentis from the Burgess Shale.

  Figure 8.7 A soft-bodied ‘trilobite’ from the Precambrian (about 565 million years old). Shaded regions in the head could be the precursor to compound eyes.

  Figure 9.1 (overleaf) This is how all Precambrian animals would have pictured their neighbours using light as a stimulus.

  Figure 9.2 Soft-bodied multicelled animals living at the end of the Precambrian. This is how the most sophisticated light receptors of the time - eyes - would have pictured the Very Late Precambrian or Early Cambrian world, around 543 million years ago.

  Figure 9.3 Graph showing the very approximate evolution of receptors for different stimuli throughout geological time. Vision is the only sense that can divide geological time into two distinct phases.

  Figure 10.1 Face-on view of our galaxy. Counterclockwise from the Sun (cross at top) are the Sagittarius-Carina arm, Scutum-Crux arm, Norma arm and Perseus arm. Triangles mark the times of the major post-Cambrian extinctions (modified from a paper by Erik Leitch and Gautam Vasisht). Some researchers believe the movement of our solar system into the spiral arms had an effect on these extinctions (such as a consequential encounter with giant meteors). The effect of unwinding is indicated by the dot-dashed lines defining the centroids of the arms for an unwinding of 1°, 4° and 8° for the first three arms, respectively.

  Figure 10.2 From left to right: a butterfly wing photographed in black and white through a crystal lens under white plus ultraviolet light; through a crystal lens under ultraviolet light only; and through a glass lens under ultraviolet light only. To the human eye each wing appears black with two blue stripes. These images reveal that the lower stripe also reflects ultraviolet light, which transmits through the crystal lens but is absorbed by the glass lens.

  Praise for In the Blink of an Eye

  “A well-written book, containing much really interesting science and a good strong hypothesis that will surely stimulate others to praise, to criticize and try to refine or replace.”

  -Washington Post Book World

  “ Parker’s research has that pop-science ‘wow’ factor—dramatic transformations over aeons of time, alien-like life forms, fragments of the secret of our own emergence.”

  -Village Voice

  “Compelling.”

  -Science News

  “[Parker is a] genius, a cool-headed logician with the soul of an artist. . . . [He] has managed to crack a mystery that evolutionists have fretted over since Darwin first sharpened his quill . . . In the Blink of an Eye might very well make him a celebrity.”

  -Seed

  “Parker’s ideas are fascinating.”

  -Boston Globe

  “Parker will have more than a few palaeontologists choking on their cornflakes.”

  -New Scientist

  “The outlines of [Parker’s] argument are laid out with compelling logic and clarity, and his solution to the Cambrian mystery seems both brilliant and obvious: we must have been blind to miss it.”

  -London Sunday Telegraph

  “In the Blink of an Eye presents its arguments the way a prosecutor presents a criminal case against the accused in a courtroom melodrama. . . . I don’t think you can find a more reader-friendly introduction to evolutionary biology.”

  -San Jose Mercury News

  “Full of fascinating scientific lore . . . The flash of unexpected insight that characterizes [Parker’s] discovery is of the rarest kind, and with a book like In the Blink of an Eye, readers have a chance to share in one of those ‘aha!’ moments that happen so infrequently in the world of science.”

  -Readerville Journal

  “[Parker’s] clarity will thrill science fans, as will his revolutionary theory.”

  -Booklist

  “Parker’s conclusion is both convincing and surprisingly fresh . . . Compelling . . . Cutting-edge science, highly recommended.”

  -Kirkus (starred review)

  “An informative work of easily accessible science.”

  -Boston Herald

  “A young, brash zoologist . . . Parker makes a compelling case.”

  -San Diego Union Tribune

  “An insightful glimpse into the mind of the scientist. . . [A] thought-provoking work.”

  -Library Journal

  “A brilliant and eminently readable evolutionary detective tale . . . Parker’s energy and intelligence are undeniable . . . [He] has led us down a remarkable trail and one hopes he has many others to explore.”

  -Roanoke Times

  “[Parker’s] central argument certainly deserves careful attention . . . fascinating examples.”

  -American Scientist

  To my parents

  When you have eliminated the impossible, whatever remains, however improbable, must be the truth

  SIR ARTHUR CONAN DOYLE, A Study in Scarlet (1887)

  Preface

  The case [for the abrupt appearance of Cambrian fossils] at present must remain inexplicable . . . and may be truly urged as a valid argument against the views [on evolution] here entertained

  CHARLES DARWIN, On the Origin of Species (sixth and final edition, 1872)

  The Big Bang in animal evolution was perhaps the most dramatic event in the history of life on E
arth. During this blink of an eye in such history, all the major animal groups found today evolved hard parts and became distinct shapes, simultaneously and for the first time. This happened precisely 543 million years ago, at the beginning of a period in geological history called the Cambrian, and so has become known as the ‘Cambrian explosion’. But what lit the Cambrian fuse?

  Until now, we have been without an acceptable explanation for this extraordinary burst in evolution - there is strong evidence against all the contending theories put forward. If time is given to consider most previous explanations, it becomes clear that in fact they explain a different evolutionary event and not the Cambrian explosion, as will be introduced early on in this book. That these two events were once amalgamated had been extremely misleading. In short, we know very well what happened during evolution’s Big Bang, indeed numerous books have already been written on this question, but we don’t know why it happened. Why it happened is the puzzle this book sets out to solve.

  The mention of a ‘puzzle’ and a ‘search for clues’ is very appropriate to the story behind the discovery of the why, and this book grew naturally into a detective story. After all, this topic will emerge as real scientific crime. I have spent many years stumbling into different fields of science, and it was while travelling along this uneven road that I ended up at the doorstep of the Cambrian. Almost by themselves, the clues towards a Cambrian theory just kept on accumulating, and eventually, after there were still no signs of evidence to the contrary, I became satisfied that the ‘truth had remained’.