MessageToEagle.com

Why Are Your Eyes So Much Older Than Your Brain?

1 August, 2013



MessageToEagle.com - Many may be unaware of the fact that our eyes are much older than our brain. The origins of the eyes have for been a mystery for a very long time.

The eyes are one of our most remarkable and precious organs. Scientists have spent years investigating the many secrets of the eyes .

Professor Trevor Lamb of The Vision Centre and Australian National University, has just published a major scientific review of the origin of the vertebrate eye and vision, summarising the findings of hundreds of scientists round the world.

"There are profound questions about the eye which are still not easy to answer because it appeared so very long ago," he says.

"Why did the eye develop? Why are there many different kinds of eye, including one for insects and crustaceans - and one for vertebrates like us?

"What kinds of animals needed these incredible seeing machines and how did they use them? How deep into time do the roots of vision go? How has the eye influenced our subsequent development?"

The deep origins of 'sight' go back more than 700 million years when the earth was inhabited only by single-celled amoeba-like animals, algae, corals and bacteria.

At this time the first light-sensitive chemicals, known as opsins, made their appearance and were used in rudimentary ways by some organisms to sense day from night.

Ancient cells already had signalling cascades that sensed chemicals in their environment, and the advent of opsins allowed them to sense light.

"But these animals were tiny, and had no nervous system to process signals from their light sensors," he explains.

Over the following 200 million years those simple light-sensitive cells and their opsins slowly and progressively became better at detecting light - they became more sensitive, faster, and more reliable - until around 500 million years ago they already closely resembled the cone cells of our present day eyes.

"The first true eyes, consisting of clumps of light-sensing cells, only start to show up in the Cambrian, about 500 million years ago - and represent a huge leap in the evolutionary arms race," Prof. Lamb says. "Creatures that could see clearly had the jump on those that couldn't.

"For example there is Anomalocaris, a metre-long predator like a giant scorpion - the "Jaws" of its day - which had eyes the size of marbles, with which to navigate the ancient seas and locate its prey. This beast, which employed the 'insect eye' model with many facets, had no fewer than 16,000 facets containing vision cells, in each eye.


Why are there so many different kind of eye?


"This generates an avalanche of information, known as optic flow, running from the eyes and along the creature's nervous system. This all has to be processed, so we also begin to see the rapid development of a central nervous system able to cope with such immense amounts of data, continually provided by the eyes and other sensory organs from the world around the animal.

"For the first time animals begin to 'see' the complex landscape which they inhabit."

Our type of eye, a single globe packing in millions of photoreceptors, first starts to emerge between 500-600 million years ago. This was the crucial moment for our vision system, Prof. Lamb contends.

"Baby sea squirts have a simple eyespot called an ocellus, which is basically a bundle of photoreceptors. The adult animal loses this, as it becomes immobile, so vision is not important. This organ appears to date back at least 600 million years.

"The hagfish has a patch of translucent skin on each side of the head where you'd expect to see its eyes, and buried beneath are a pair of very simple 'eyes' with light sensing cells and a simple optic nerve - but no muscles, lens or iris. Hagfish ancestors go back more than half a billion years, so this crude light sensing organ seems to have been the start of something big."

Lampreys also appeared around 500 million years ago, and have a pair of camera-style eyes remarkably similar to our own. These appear to be direct forerunners of the vertebrate eye, which we have inherited through our fish ancestry, says Prof. Lamb.

"From this we can say that the vertebrate-style eye has been around at least 500 million years - and although its light-sensors and signalling systems are very similar to those of insects and other invertebrates, its optical system evolved quite independently from the insect-style eye with its many facets."

Paired eyes also appear to feature in the strange 'crest animals' found by Chinese scientists in rocks that are around 500my old. From then on the basic plan of the vertebrate eye becomes more settled, being used with innumerable refinements by fish, amphibians, reptiles, birds, mammals and, eventually, us.

"The advent of spatial vision provided immense survival value to the creature that had it - but the process occurred slowly, over countless steps, with the transition from a simple eye spot to the vertebrate-style camera eye possibly taking as long as 100 million years," he concludes.

MessageToEagle.com

See also:
Bizarre Neuroscience Of Immortality: Scientist Wants To Die So He Can Live Forever

Follow MessageToEagle.com for the latest news on Facebook and Twitter !

Don't Miss Our Stories! Get Our Daily Email Newsletter

Enter your email address:


Once you have confirmed your email address, you will be subscribed to the newsletter.

Recommend this article:

Amazing Memory - People Who Remember Every Day Of Their Life


Our Brain Is A Holographic Machine Existing In A Holographic Universe

Stanford brain researcher and the quantum physicist, Dr. Karl Pribram, was long puzzled by a perplexing question...


Is A New Race Of Super Earthlings Being Born Or Is This The End Of The Human Race? - Scientists Ask

Subscribe To Our Space, Astronomy, Astrophysics, Earth and Xenology News!

Grab the latest RSS feeds right to your reader, desktop or mobile phone.


comments powered by Disqus

Subscribe to RSS headline updates from:
Powered by FeedBurner

Go to - MAIN PAGE

Copyright © MessageToEagle.com All rights reserved.
Go to - MAIN PAGE


Advertise With Us!

Submissions

 Subscribe in a reader

Join Us On Facebook!

Other Popular Articles


Mysterious Brain Of Daniel Tammet - A Scientific Rosetta Stone

Daniel Tammet has one of the most extraordinary brains on Earth! There are still many things scientists do not know about...


Upload Your Brain Into A Hologram: Project Avatar 2045 - A New Era For Humanity Or Scientific Madness?

Would you like to live forever? What do you think about the idea that your conscious mind will be uploaded into a hologram?

Mind & Brain:

Inside The Mind Of Lucid Dreamers: People Who Can Control Their Dreams And Perform Actions

Tractor Beams Of Light - No Longer Pure Science Fiction!
Science fiction meets real science! "Tractor beams" - fascinating invisible beams that can push and pull objects, leave science fiction domain. The concept of "tractor beam" used in science fiction films and books to haul spaceships and capture floating capsules gains scientific attention.


Star Trek Tricorder - Now Available Online For Anyone To Build!


Do We Live In A Computer Simulation Created By An Advanced Alien Civilization?


Spying On People Inside Building Through The Walls


Biometrics: Eye-Scanners Can Be Fooled


European Physicists Break Quantum Teleportation Record!


Incredible Crystal Star City Hovering In The Air - It Looks Just Like An Alien Invasion


Levitating Ball Defies Gravity - Incredible Technology Of The Future

Technology:


Space-Time Crystal Computer That Can Outlive Even The Universe Itself!

World’s Thinnest Screen Created From A Soap Bubble

Brilliant Idea: Scientists Create Toilet Which Turns Poo Into Electricity

Most Important Innovations In The Next Five Years - From IBM

Visit The Most Extreme Soundless Place On Earth

Amazing Technology: Bio-Powered Lamp Absorbing CO2

W3Counter