The eyes might have it [Evolution, the Cambrian explosion]

The Age (Australia) ^ | 30 August 2003 | Deborah Smith

[PatrickHenry]

An Australian biologist believes the evolution of vision may hold the key to animal life as we know it, writes Deborah Smith.

Dr Andrew Parker will never forget his first dive over the Great Barrier Reef. Even as a biologist, he was surprised by the blaze of colour and vast array of creatures he saw in the water. And, in a memorable encounter, he came eye-to-eye with a large group of cuttlefish.

The small molluscs, watching the human intruder closely, put on a spectacular wave of colour changes: the brown bleaching from their bodies as he first approached, followed by a flash of fiery red and then a tranquil green as he swam away.

Parker did not realise it at the time but captured in that moment were all the elements - eyes, colour and fear of a predator - that would lay the foundation for his "light switch" theory about the extraordinary diversity of life on Earth.

About 543 million years ago, the world was a dull rather than brilliant place, inhabited by primitive sponges, jellyfish and worms. But in a dramatic event known as the Cambrian explosion, the number of major animal groups skyrocketed from three to the 38 we know today, in a matter of a few million years. "It involved a burst of creativity like nothing seen before or since. Animals with teeth and tentacles and claws and jaws suddenly appeared," says Parker, an Australian researcher at the University of Oxford in England.

The reason for this short evolutionary flourish has mystified many, not least Charles Darwin. But to Parker, the explanation now seems blindingly obvious: the evolution of the eye.

Fossils records show the first creature to develop an eye was a small trilobite that lived at the very beginning of the Cambrian period. With the power of vision, it would have found easy prey in the blind, soft-bodied creatures around it. "The evolution of that very first eye must have been a monumental event," says Parker.

"A light switch was turned on. All animals (even those without eyes) needed to be adapted to vision before they were eaten, or before they were outwitted by their prey."

Parker was speaking from an overcast Oxford on the eve of a trip to Sydney to give a public lecture, launch a book on his theory, In the Blink of an Eye: the cause of the most dramatic event in the history of life, and give seminars at Sydney Grammar School. He recalled with fondness Australia's bright sunlight. It was its sunny climate that influenced the evolution of tiny sea creatures called seed-shrimps. While working at Sydney's Australian Museum, Parker discovered that they had iridescent hairs. This set him on the path to his theory.

Not all fossil experts accept Parker's ideas, most notably, Cambrian specialist Professor Simon Conway Morris, at the University of Cambridge, who concluded recently that it was "appealing" but "no more convincing" than other theories, such as a rise in atmospheric oxygen levels or a drop in carbon dioxide.

The nature of the Cambrian explosion is still misunderstood by some, Parker says. Recent genetic evidence suggests the internal body shapes of the different animals evolved over hundreds of millions of years. The explosion was in their outer appearance - the hard, spiky, grabbing and colourful bits necessary to survive in a new world order triggered by vision.

For a researcher, writing a popular science book has been a lengthy learning experience, Parker admits. "At first, I would take a scientific manuscript and substitute all the difficult words with everyday words. But it doesn't work." The breakthrough came when he realised he should "start from the beginning and tell a story".

British-born but now an Australian citizen, Parker came to Sydney more than a decade ago. One of his first projects was to describe the many new species of seed-shrimps found off the coast. It was while examining one of these tiny creatures early one evening in the laboratory that his life course was changed, when he witnessed a flash of green light coming from hairs on its antennae. Parker discovered this iridescence was used in a courtship display when some seed-shrimps he had collected were caught mating on camera.

With the help of physicists at the University of Sydney, he found the seed-shrimps flashed green as a result of diffraction gratings - fine regular grooves that reflect light in the same way as a credit-card hologram.

Well-known in physics, this was the first time diffraction gratings had been found in nature. Many colourful creatures have since been identified as having them.

Much of Parker's tale involves the 515 million-year-old Burgess fossils in Canada, which are an extraordinary record of the bizarre creatures the Cambrian period spawned. By studying fossils with lasers, Parker found some of the ancient creatures had diffraction gratings too. He made exact models, and when he placed them in shallow sea water under light, they beamed brilliant colours. "An almost unimaginable piece of Cambrian history had been revealed," he says.

[PatrickHenry]

Everybody be nice.

[PatrickHenry]

PING. [This ping list is for the evolution side of evolution threads, and sometimes for other science topics. FReepmail me to be added or dropped.]

[PatrickHenry]

I goofed. Could you fix my title for me? It has "the the" where I should have only one "the." Thanks.

[general_re]

Phasers set to "facilitate", Captain...

[haywoodwebb]

Professing themselves to be wise, they became fools . . .

Romans 1:22

[PatrickHenry]

For your information: many of the regulars on the science threads here on Free Republic have joined in the AGREEMENT OF THE WILLING to promote civil discourse and to avoid flame wars which lead to excessive use of the abuse button, transfer to the Smokey Backroom, and ultimately ... thread deletion. I respectfully ask that you read the linked agreement so that you will know what the willing parties expect of one another and their dealings with others.

When in doubt, please engage your Virtual Ignore switch.

[CobaltBlue]

Figuring out the evolution of the eye will drive the IDers nuts.

[Dimensio]

Figuring out the evolution of the eye will drive the IDers nuts.

No, it will just give them another bit of strong evidence to dismiss without consideration.

[f.Christian]

To the slaughter house ... the blind --- lunch meat !

All thanks to evolution ... rag head science --- liberals !

The govt is functioning under herd instinct now ... cattle pens --- packing house !

Social engineering ... feed lot education too !

[Prof Engineer]

ping

[week 71]

all the components of the eye are extremely complex. Just to evolve a simple functional protein is quite an accomplishment. This explains way some species from the cambrian era have photo receptive cells and an ocular tube, and simply lack a transparent lens. why not a lens? this would give the creature the ability to see images. the lens that animals have is just some proteins. for six hundred million years they have been unable to evolve a simple protein. interesting to see the amt of much more complicated evolution that has taken place in the same six hundred million years.

[pabianice]

So how does he explain how Hillary looks?

[Question_Assumptions]

Without inserting God or some other supernatural agency into the picture, traits don't evolve "because" of anything other than mutation. A creature mutates and the mutation is kept, or not, because it makes the creature more likely to survive. Mutations don't suddenly start happening because a species has an environmental need to mutate. They are mistakes and only the good ones are kept. Where this explanation fails, for me, is that it doesn't seem to explain why these hard body and eye mutations would suddenly happen -- in parallel in multiple animal families -- at the same time and in the same way.

[LiteKeeper]

Fascinating Cuttlefish

Trilobite Technology

[jennyp]

That certainly is an intriguing hypothesis. The sense of sight does open up a vast new class of both risks and opportunities. I'm sure it'll spawn lots of new research in unexplored areas.

Here are some more articles & reviews of Parker's book, as found at Creation/Evolution: The Eternal Debate:

Posted Date	Title	Cached?
2003-08-24	Between the Lines with Andrew Parker	yes!
2003-08-07	On the First Day, God Said . . . (review of "In the Blink of an Eye")	no
2003-07-22	Eyes key to theory for early explosion of life	yes!
2003-06-02	In the Blink of an Eye, by Andrew Parker (book review)	yes!

[LiteKeeper]

The Fossil Record: Becoming More Random All the Time

[f.Christian]

cuttlefish ?

How different is this than reading chicken entrails ... tea leaves --- crystal balls --- hand palms -- mind reading ?

[longshadow]

pre-Cambrian monochrome placemarker

[Prairie Apologist]

"At first, I would take a scientific manuscript and substitute all the difficult words with everyday words. But it doesn't work." The breakthrough came when he realised he should "start from the beginning and tell a story".

Exactly - when logic and evidence fail... it's storytime

There is no problem with postulating a theory like this for the purpose of discussion and attempting to understand how living organisms function. The problem is that some ignorant obstinate high school teacher is going to start using this as FACT in the classroom.

The funny thing is that scientists used to think the earth was fairly young or they just admitted there was no way to really know the age of the earth but once they embraced the theory of evolution they needed time. LOTs and LOTS of time, and so they came up with about 4 billion years. Then they realized that under their own theory they only had a small portion of that to work with. And then came the discovery of the cambrian explosion, and things got a little tight.

When they say that the incredible diversity of different groups appeared
over a period of 3-5 million years. You have lots of paleontologists who get REALLY uncomfortable because they are talking about mere inches of strata on one side little to know life on the other every phyllum that exists to this day - plus a few that have since gone extinct.

So the sudden appearance of complex and abundant life on earth is never to be misunderstood as the signature of creation.

And the continual discovery of dinosaur and pleistocene animals fossilized in enormous log jams of death is not to be viewed as any evidence of a global catastrophe or flood.

My favorite anomolies are the logs and trees that are found fossilized
vertically protruding through 65 million years worth of layers. Oops.

But those are theory killers so they are not displayed at the smithsonian.

[DannyTN]

"The breakthrough came when he realized he should start from the beginning and tell a story"

Yep, how many "scientists" have figured out funding, book sales, even peer approval is tied to their ability to tell stories?