In Chapter 1, I described how the Earth passed through spells where it was covered, or nearly covered, in ice a kilometre thick. Certainly the retraction of this ice could have stirred up minerals in rocks on a grand scale. As those huge ice sheets traversed the land, they would have ripped open the surface layers of rocks and absorbed minerals, transporting them to the sea. Unfortunately, though, the timing is a little out. The Cambrian explosion took place between 543 and 538 million years ago, and the last Snowball Earth event ended 575 million years ago at the latest. So there is a difference of at least thirty-two million years between these two events. This might be just too great - theoretically an eye can evolve within half a million years. So I still believe that the last Snowball Earth event should be coupled to the Precambrian ‘surge’ in evolution rather than with the Cambrian explosion.
Research in this area of the geological history of media transparency is still in its infancy; hence my discussion of this subject has been brief. In the future it is to be hoped that all will become as clear as the Late Precambrian environment itself.
A final word
The Light Switch theory is a consequence of recent fossil finds and evolutionary analyses (although the philosophy of colour today weighs in heavily, too). There remains an imperfection in the geological record that is still to be reckoned with, but it no longer looms before us as it did in Darwin’s days. Palaeontologists today are striving to fill the ever narrower gaps in the fossil record, searching all corners of the globe for new species that lived near the time of the Cambrian explosion.
Originally I was afraid that the Light Switch theory might appear far-fetched, particularly since most alternative theories had been heading in very different directions. Eyes the cause of the Cambrian explosion? How ridiculous! But it was the amalgamation of modern biology with Cambrian palaeontology that finally settled my nerves. Now, after considerable contemplation of the power of vision today, I am convinced that the evolution of that very first eye must have been a monumental event in the history of life on Earth. For this fact alone I am happy to share my ideas with a wider audience. Whether that introduction of the eye really did coincide with the beginning of the Cambrian explosion should be answered with greater precision as new fossil finds are unearthed from near that Early Cambrian border. But at this stage in our knowledge, this relationship appears remarkably close.
My final reassurance that the Light Switch theory is both a judicious and logical one came from the editor of a newspaper. James Woodford, a journalist with the Australian newspaper the Sydney Morning Herald, wrote a comprehensive article on my theory. This made the front-page headlines, and gave the newspaper’s editor cause for concern. The night before publication, and just before the article and the paper went to press, James received a question from his boss. The question was, ‘Are you sure this has not been said before?’ That was extremely comforting. It meant that this was an obvious answer. In fact it was so obvious that it had little scientific merit - anyone could have come up with it. True. Now I think that this is the obvious answer.
Recently I went swimming off the coast of Sydney. Here I encountered a group of cuttlefish similar to those that had initially woken me up to biodiversity, as described in the first chapter. Again the cuttlefish surrounded me in an arc and displayed spectacular colour changes. Again they looked at me with their large sophisticated eyes, and flashed their sophisticated colour display, as if confirming the importance of light in nature. Yes, I thought, vision has really entered the behavioural system of animals. Then I noticed a crab on the sea floor. I zoomed in on its eyes, and reflected: the origin of those arthropod eyes had a lot to answer for . . .
Index
Page numbers in italics refer to illustrations and figures in the text.
Ausktribosphenos nyktos
Abe, Katsumi
Abyssal Plain
acetate, fossil casts
acorn worms
adaptation; beetle exoskeletons; to light; to vision; see also selection pressures
adaptive camouflage
adaptive radiation
Adoutte, André
Africa
Agassiz, Jean Louis Rodolphe
agnathans
Akhenaten, Pharaoh
Alberta, Canada
alciopids
algae
Amazon river
amber, flies in
amino acids
Ammolite
ammonites
ammonoids
amoebae
amphipods
Ancalagon
angelfish
annelids
Anolis lizards
Anomalocaris
Antarctica
antennae, seed-shrimps
apposition eyes
aragonite
Archimedes
Aristotle
ark clams
armies, use of colour
armour: evolution of; spines
arrow worms
art: ancient Egyptian; Impressionism
arthropods; Burgess Shale fossils; Cambrian explosion; defences; eyes; as predators; senses; three-dimensional models
Asheaia
Asia, plate tectonics
Astyanax mexicanus
Atlas moths
atmosphere: carbon dioxide levels; light levels; oxygenation of
auk, great
Aurelia aurita
Australia: Great Barrier Reef; placental mammals; SEAS expedition; sedimentary rocks; stromatolites; upside-down flies; Wollemi pines
Australian Museum
Australian Navy
Axial Seamount
Azygocypridina
Azygocypridina lowryi
bacteria: ancient spores; cyanobacteria; in hot springs; in hydrothermal vents; light perception
‘baked bean’ seed-shrimps
Balavoine, Guillaume
Barrington, Daines
Bates, Henry
Bathynomus
bats
beach fleas
beaks, squid
bees
beetles: camouflage; exoskeleton adaptation; Messel beetles; pigments; structural colours; ultraviolet colouration
behaviour, adaptation to light
‘the bends’
Bengtson, Stefan
Bergström, Jan
bifocal glasses
‘Big Bang’ of evolution see Cambrian explosion
biodiversity; cave animals; day/night differences; deep-sea animals; and light levels
bioluminescence
birds; courtship displays; disruptive colouration; eyes; footprints; fossils; magnetic detectors; relationship with dinosaurs; species; ultraviolet vision
birds of paradise
birds of prey
black smokers (hydrothermal vents)
Blake, William
blanket fog, in Precambrian
blue light: seed-shrimp iridescence; thin films; trilobite eyes; under water
blue-green algae see cyanobacteria
body plan see external hard parts; internal body plans
bones: fossilisation; muscle attachments
Book of the Dead
box jellyfish
Bragg, Sir William
brain, visual processing
Briggs, Derek
bristle stars
bristle worms; Burgess Shale fossils; diffraction gratings; eggs; eyes; feeding parts; light perception; senses; spines; swimming ability
brittlestars
brook lampreys
Burgess Shale fossils; chordates; defences; diffraction gratings; discovery and excavation; environment; eyes; formation of; importance of; predators; prey species; trilobites
Burney, Fanny
Butterfield, Nick
butterflies
calcite lenses
calcium phosphate
Cambrian explosion; colour in; dating of; external body parts; eyeless chordates; eyes in Cambrian fossils; eyes as cause of; food webs; fo
ssils; possible explanations; predators; reconstructions of Cambrian period; trigger for evolution of eye; trilobites
Cambridge project
Cambropachycope
camera obscura
camera-type eyes
camouflage: as adaptation to light; adaptive camouflage; chromatophores; colour; countershading; disruptive colouration; in evolution; light conditions and; mammals; mimicry; predators; shadows; silver colouration; soldiers’ use of; transparency; under water
Campsoscolia
Canada
Canadaspis
Canadaspis laevigata
Canadia
carbon dioxide, in atmosphere
Caribbean Sea
carrion beetles
cats
cave fish
caves; adaptations to lack of light; bioluminescence; cave paintings; colour of cave animals
cells: nucleus; organised colonies; single-celled organisms
cephalopods
chameleons
chemical defences
chemical receptors
Chen Junguan
Chengdu Institute of Geology
Chengjiang
China
chitin
chlorophyll
Choia
chordates; eyeless; eyes; fossils; hearing; pressure receptors
chromatophores
chromosomes
cicadas
cichlid fishes
cladistics
clams
Clarkson, Euan
classification of animals
Claudina
climate, carbon dioxide levels in atmosphere
cloning, revived DNA
Clydagnathus
cnidarians; body plan; Burgess Shale fossils; eyes; senses
Cohen, Anne
collagen
Collier, Frederick
Collins, Des
colour: and adaptation to light; in ancient Egyptian art; bristle worms; Cambrian fossils; cave animals; chromatophores; colour mixing; courtship displays; Darwinian view; deep-sea animals; disruptive colouration; existence of; in fossils; iridescence; mimicry; Newton’s theory; photography; pigments; Poulton and; selective pressure; television; ultraviolet; under water; use by warriors; warning colouration; see also camouflage; structural colours
comb jellies; body plan; Burgess Shale fossils; senses
compound eyes; acute zones; apposition eyes; evolution; focusing; holochroal eyes; in prey species; schizochroal eyes; sessile eyes; single eyes; stalked eyes; superposition eyes; trilobites
computer-aided design (CAD)
conches
conifers
conodonts
continental shelf
continental slope
continents, movement of
convergence
Conway Morris, Simon
corals
cornea
countershading, camouflage
courtship displays: birds; butterflies; humans; seed-shrimps
crabs; breeding strategy; eyes; iridescence; luminescence; senses; sounds
crayfish
crickets
crocodiles
crustaceans; evolution from trilobites; eyes; marine cave animals; scavenging
crystals, liquid
Cunningham, J. T.
cuttlefish
cyanobacteria
Cypridinidae
darkness: in caves; at night; in oceans
Darwin, Charles; on colour; Down House; on the eye; on fossils; On the Origin of Species
deep-sea animals, eyes
defences, prey species
Denton, Sir Eric
Descartes, René
deserts
detectors; chemical; eyes as; gravity; mechanical; sound : see also light perception
Dickinsonia
diffraction gratings; bristle worms; Burgess Shale fossils; discovery of; right-way-up flies; seed-shrimps; upside-down flies
digestive systems, fossil evidence
dinoflagellates
dinosaurs; DNA; dung; extinction of; footprints; fossils; predators; reconstructions; relationship with birds; sounds
Diplodocus
disease
disruptive colouration
diversity see biodiversity
DNA; in cell nucleus; cloning; from dinosaurs; mapping diseases; sexual reproduction
dodo
dolphins
Down House, Kent
Doyle, Sir Arthur Conan
dragonflies
Drosophila
dung beetles
eagle owls
ears
Earth: movement of continents; passage through spiral arms of galaxy; ‘Snowball Earth’ hypothesis; see also atmosphere
earthworms
echidna
echinoderms
Ediacaran fossils
egg, sexual reproduction
Egypt, ancient
electric eel
electric fish
embryos, direct development
energy, bioluminescence
environment: and adaptation to light; and adaptive radiation; Burgess Shale; and convergence; possible explanations for Cambrian explosion
Erwin, Doug
Euglena
evolution: adaptive radiation; convergence; diversification; effects of vision on; of eyes; importance of fossils to study of; laws of survival; in low-light environments; macro-evolution; micro-evolution; of news media; nocturnal animals; and plate tectonics; predetermination assumption; regressive evolution; senses; sexual reproduction; species; trigger for evolution of eye; see also adaptation; Cambrian explosion; selection pressures
Exner, Sigmund
exoskeletons, beetles
external hard parts: and Cambrian explosion; convergence; defences; selection pressures
extinctions; extraterrestrial causes; mass extinctions
extraterrestrial life
eyeless chordates
eyeless seed-shrimps
eyes; at night; as binary detectors; camera-type eyes; as cause of Cambrian explosion; cave animals; colour vision; convergence; deep-sea animals; evolution of; focusing; fossils; importance to predators; iris; mirror eyes; in non-arthropod phyla; pinhole eyes; position of; predators; as selection pressure; sessile eyes; simple eyes; size of; stalked eyes; trigger for evolution of; trilobites; see also compound eyes; lenses; retina; vision
eyespots (light detectors)
eyespots (patterns)
Fallotaspis
Fallotaspis typica
fan worms
Fasciculus
feeding: fossil evidence; seed-shrimps; see also predators; prey species
Fermat, Pierre de
Field, British Columbia
Field Museum of Natural History, Chicago
fish; camouflage; cave fish; electric fish; eyeless; eyes; jawless; living fossils; magnetic detectors; pressure receptors; silver colouration
flamingos
flatworms; body plan; light receptors; marlin parasites; senses
flea beetle
flies
flight
Flinders Ranges
focusing; compound eyes; graded lenses; simple eyes
fog, in Precambrian
food pyramid, nocturnal animals
food webs: Cambrian explosion; cave animals; eye position and; marine scavengers
footprints, trace fossils
forensic science
Fortey, Richard
Fortiforceps foliosa
fossils: Cambrian explosion; chordates; colour; cyanobacteria; defences; definition of; Ediacaran fossils; eyes; formation of; importance in study of evolution; interpretation of; living fossils; phosphatisation; plants; plate tectonics and; Precambrian Period; predators; reconstructions; structural colours; sub-fossils; three-dimensional models; trace fossils; see also Burgess Shale fossils
Franklin, Benjamin
Fraunhofer, Joseph von
frogs
&
nbsp; fruit flies
Fuxianhuia
galaxy, Earth’s passage through spiral arm
Garcia-Bellido, Diego
Gatesy, Stephen
gemstones
genes: and convergence; extinct genes; genetic drift; and internal body plans; sexual reproduction
geological timescale
Germany
gigantism, deep-sea animals
Ginkgo
Giotto (Ambrogio Bondone)
giraffes
glass
glasses, bifocal
global warming
glow-worms
goanna
gold leaf, in ancient Egyptian art
Gould, Stephen Jay
graded lenses
Granton Shrimp Beds
grasshoppers
gravity detectors
Gray, Mike
Great Barrier Reef
green light: seed-shrimp iridescence; thin films
greenhouse effect
Greenland
guineafowl
guppies
hagfishes
Haikouella
hairs, chemical detectors
Halichondrites
Halkieriids
Hallucigenia
Halocyprida
halophores, seed-shrimp antennae
Hamelin Pool
hammerhead sharks
handedness, trilobites
Haplophrentis
hard parts see external hard parts
Harper, Charles
Harvard University
Hawaii
healing ability, trilobites
hearing
heliography
Hennig, Willi
Hercules beetle
Heron Island
Herring, Peter
herrings
Hertz, Heinrich
Himalayas
Hinton, H. E.
Holbein, Hans the Younger
Holmes, Sherlock
holochroal eyes
holograms
Hooke, Robert
Hoplophoneus
hornbills
horses
horseshoe crabs
hot springs
Hou Xianguang
houseflies
Hoyle, Sir Fred
humans: courtship rituals; eyes; handedness
humidity, and structural colours
hummingbirds
In The Blink Of An Eye Page 33
