In the Blink of an Eye

Rating:
Summary: Superb sythesis of the data
Review: In his book, In the Blink of an Eye, Australian biologist Andrew Parker offers a new perspective on the so-called Cambrian explosion. Using a vast repertoire of supporting data from subjects as diverse as economics and optics, he builds a very cogent case for the introduction of a new biological sense that changed all the rules for a then very ancient living world. Although it gets a little bogged down in the discussion of shrimp, their light production and vision, the overall text is full of interesting illustrations of his thesis and conclusions to be drawn from them.

To begin with, the author looks at what life is very probably to have been like during the Dark Ages of the Precambrian. Professor Parker approaches the subject by suggesting that internal and external body plans have had different evolutionary histories and rates, and that the basics of internal body plan-those aspects that are not preserved well if at all in the fossil record-had already arisen during that early period of life's existence. Those changes in structure that would require the greatest effort and the most time, were so firmly set by the end of the period that while some phyla have dropped out, no new ones have been created. Focusing on the newer interpretations of the Ediacaran and Burgess life forms, the author believes that most of the external body plans were worm-like because there were few forces for the development of others. While the internal structures were distinct to accommodate different niches, the externals remained unchanged.

Everyone agrees that the efflorescence of external forms, particularly those with hard parts, after the Cambrian was both prolific and amazing. For Darwin, who had no access to information on Precambrian life or genetics, it posed a major challenge to his theory of evolution. It appeared as if life came diverse and fully formed out of nowhere and began to proliferate exponentially from its first appearance. What everyone hasn't agreed on heretofore is the reason for that sudden burgeoning of body forms.

Professor Parker takes the reader through various arguments that illustrate his thesis, namely that prior to the Cambrian it was essentially a blind world. He suggests that prior to that point in time light could be sensed, but visual images were not possible, that neither the "hardware" nor the "software" for actual vision existed. Without that sense predation, while it existed, was almost accidental. Once the creation and interpretation of images was possible, vision drove the evolution of both predator and prey in an escalating manner.

Superb reconstruction of an unusual time in life's history.


Rating:
Summary: Lighting the path of evolution
Review: In this illuminating [sorry!] study, Parker contends that light is the driving force behind evolutionary change. Light, he argues, is the most prevailing environmental element. Crossing biology, geology, ecology and physics with a bridge of optics, he shows how many body structures have varied due to light's availability and intensity. Most important to the reader, is his contention that when life developed a greater sensitivity to light, evolution was given a significant boost. We call the time of that "boost" the Cambrian Explosion. According to Parker, the mechanism driving the boost was the evolution of the eye. The wide diversity exhibited by evolution's abrupt advances around 550 million years ago produced creatures whose descendants are cats, bears, birds, and you. Parker provides a wealth of background material in developing his thesis. The forces of plate tectonics, the way light is absorbed, reflected, bent, and even biologically generated are all presented. He shows the relevance of each aspect in a slowly and carefully built concept.

Parker presents his theme with verve. "Let there be images!" is a concluding example. New ideas in science tend to use a forceful approach. Since he's laid a firm Darwinian foundation for this exclamation, perhaps his enthusiasm is warranted. He explains much about early life, the nature of light and how animals have adapted body plans to use light effectively. Parker shows how new research tools can analyse fossils to reveal the past wasn't the soft, dull, colourless world often portrayed. Some of the tricks developed by Nature millions of years ago weren't duplicated by human technology until very recently. Light, he explains, was both an attractant and a repellent in the shallow seas of early oceans.

The mortar binding the facets of Parker's idea is predation. Both eaters and eaten needed to detect each other to survive. In parallel with the eye, bodies changed to avoid detection and deflect biting mouths. Survival in evolutionary terms, he reminds us, means more than eating or avoiding being a meal. Vision enhanced the process of sexual selection, with the new body forms exhibiting colours to attract mates. These and other factors combine to provide what Parker calls his "Light Switch" view of the Cambrian period. As a foundation for his hypothesis, Parker joins the ranks of Eldredge and Gould's "punk-eek" [punctuated equilibrium] cabal of evolutionary biologists. This step is taken to grant eye evolution a rapid pace in line with the many changes the Cambrian Explosion seems to evidence. That's unfortunate, since it isn't necessary and he refutes the idea many times in citing his own evidence. A species span of
120 million years without a bump is equilibrium indeed!

Parker's ebullient prose is supplemented by excellent line drawings and photographs. These provide both background and examples of his points. His style, while ardent, is a bit rambling, although this can be forgiven in a book covering so many aspects of evolution's path. What cannot be forgiven is the lack of any bibliography or notes. This lack is outrageous and insults the reader. Although many researchers are presented, few titles grace the pages, leaving the reader with the task of seeking further information or confirmation almost from scratch. The publisher has no excuse for allowing this lack. Read this book, reflect on Parker's ideas, and remember there are other proposals for the cause of the Cambrian Explosion equally or better presented. [stephen a. haines - Ottawa, Canada]

Rating:
Summary: Okay, I'll be the naysayer
Review: No thinking person can deny that the presence of light in the environment can be an important selective pressure. Indeed, as Parker argues, it may have been one of the most important influences on the evolution of locomoting organisms since locomotion began. In a very small nutshell, his thesis that adaptation to light, especially the development of sensory mechanisms to take advantage of light in the environment, is reasonably easy to believe.

I am a student of perception and I wanted to be persuaded by Parker's argument, but the book itself is not well done. There is a ridiculous attempt to generate suspense about the conclusion Parker ultimately draws...a conclusion that is basically no surprise if you read the dust jacket. The language is often stilted and pedantic, to my eye, making me wonder if this isn't a warmed-over dissertation recast as pop science.

The most irritating element of the book, however, is the routine citation of items from the research literature...but with no reference list to which to turn for the full citation. Even decent popular science books have at least a few sources for further reading, and notes of some sort for the particulars of research cited. Parker's book has neither.

The book has some value (hence the three stars) for pointing out a variety of interesting elements of invertebrate visual system evolution, but does not help at all if one wants to follow up such threads.

Okay, I'm not a paleontologist and not a biologist, so maybe I'm talking through my hat. Simon Conway Morris, however, IS an eminent paleontologist. If you want a truly informed review of Parker's book, see Morris's review in American Scientist, July/Aug 2003, p. 365 ff. Quoting very briefly: "The jaunty style becomes increasingly irritating, and the claims for scientific originality increasingly questionable."

Rating:
Summary: In the Blink of an Eye from a geologist's point of view
Review: Parker's book was extremely interesting. As a geologist, I was delighted to find a book that was not completely bogged down with scientific terminology, so that I could pass this book on to my friends and family and share my interest. For someone who is not a geologist or biologist, a few of the terms may be a bit heavy. However, I believe for any science, paleontology or geology geek, this book is a must-read. The exploration of the Cambrian life forms is fascinating, the chapter on eyes alone is amazingly informative and very interesting. The reader will be swept away by Parker's enthusiasm and honesty. Especially enjoyable were his description of the male seed shrimp's attempts to court a female, and the descriptions of the predators and prey of the Cambrian. I have become enamored of Trilobites after reading this book, creatures I had previously not given a lot of thought.

Rating:
Summary: Okay, I'll be the naysayer
Review: The story of how sight evolved 540 million years ago and what it did to fauna and flora of the earth. Unbeleivable that life could not see before that time. This is an excellent book, well put together and researching subjects other that those outlined in the book. An excellent buy which will amaze you and keep you reading.
This book is a 10+ and recommended to buy.

Rating:
Summary: Incredible that I can see.
Review: The story of how sight evolved 540 million years ago and what it did to fauna and flora of the earth. Unbeleivable that life could not see before that time. This is an excellent book, well put together and researching subjects other that those outlined in the book. An excellent buy which will amaze you and keep you reading.
This book is a 10+ and recommended to buy.

Rating:
Summary: What Caused the Big Bang in Animal Evolution
Review: There have been living creatures on Earth for about four billion years, but most of that time they were blind. Most of that time, also, they were very simple (single cell animals, sponges, and soft-bodied animals). The famous Cambrian explosion was the sudden boom in animal diversity that happened between 543 and 538 million years ago. It is when teeth and armor appeared. It is also when eyes appeared. It is easy for us to imagine the drama of, say, the destruction of the dinosaurs 65 million years ago, but according to Andrew Parker the Cambrian explosion is "the most dramatic event in the history of life." Other dramatic events have their explanations (an asteroid wiping out the dinosaurs, for instance), but there has not been a satisfactory explanation of the Cambrian boom. Until now, according to Parker, and he has come up with it. _In the Blink of an Eye_ (Perseus Publishing) is a convincing explanation that he first announced seven years ago: the Cambrian explosion was caused by the evolution of vision.

What happened in the explosion is that animals acquired armor, hard body parts, and a huge variety of different shapes. Parker explains that the shapes and armor came along because eyes came along. In the blind pre-Cambrian world, creatures took in sensation by smell / taste, sound, or touch. It did not matter what the creatures looked like, because no other creature could see them. It didn't matter if creatures had no armor, because predators weren't chasing them. Creatures scavenged upon dead animals, but did not need claws or jaws to catch those; catching prey was unlikely for a creature that was blind, so predation was not the rule. And then there was light! Parker thinks that a soft-bodied ancestor of the trilobite was the first creature to get a light sensitive patch that eventually differentiated into different units of an eye. The trilobite that could gradually see better could gradually become a better predator. Not only does vision power a diversity of the trilobite itself, into such skills as agility and efficient use of muscular propulsion, it powers changes in prey. In the dark, an animal has no need to care what it looks like. Pursued by creatures that can see, an animal has many avenues of change that it might follow, like making camouflage, developing its own armor, swimming faster, growing bigger, or gaining its own eyesight. And then the predators can become modified to overcome those tactics, and the familiar evolutionary battle is enjoined in earnest. Vision started diversity, and has powered it ever since.

Parker's book is a rich account of how he came to these conclusions, with a wide-ranging gathering of supportive evidence. He writes clearly, and with a witty understatement. When, for example, he describes examining seed-shrimps and dissecting them under the microscope, he says, "The seed-shrimps tend to roll around and fall in exactly the positions that are not required of them." Any scientific theory is open to question, and surely the very simplicity of Parker's explanation will make it a target for other theorizers with new data. Right now, though, in considering the Cambrian explosion, the Light Switch Theory is the way to see things.

Rating:
Summary: Great theory, described moderately well
Review: This book's theory is attractive enough that many experts ought to feel embarrassed that they didn't propose it earlier. It's not so much that people looking at the Cambrian explosion should have seen the evidence pointing to this theory - the book tends to indicate that some important pieces of evidence were only found in the last decade or so. What puzzles me is why nobody modelled the effects of the evolution of eyesight well enough to decide to go looking for the results in the fossil record. This makes me wonder whether a lot of experts are still uncomfortable with the punctuated equilibrium model of evolution.
But the book's style leaves much to be desired. It often goes off on irrelevant tangents. The absence of references to scientific literature is disappointing. I'm annoyed by the way he presents numbers such as "543 million years ago" with little indication of how accurately they are known.