A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Marine Worm Has Insectile And Vertebrate 'Eyes' (Update)
How did a complex structure like the human eye evolve? Charles Darwin recognized that the eye would be a real test of the theory of evolution. He suggested that it might be possible to evolve an eye from "imperfect and simple" forms:
"To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.
Scientists today believe that the eye could evolve from a single light-sensing cell. Scientists disagree over whether it evolved just once, or many times.
Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real."
It turns out that Nature is both creative and generous with her gifts. Recent research has shown that the tiny marine worm Platynereis dumerilii has two types of light-sensing cells. The eyes of the worm have rhabdomeric photoreceptors, a compound lens formation that is seen almost exclusively in insect eyes. Rhabdomeric photoreceptors are covered in little finger-like protrusions. In its brain, however, it has a different kind of light-sensing cells - ciliary cells that are seen in vertebrate animals. Ciliary cells have hair-like cilia that extend outward and branch out like tiny umbrellas. Two different ways of sensing light in a single organism!
Researcher Joachim Wittbrodt of the European Molecular Biology Laboratory in Heidelberg, Germany speculates that the ciliary cells may regulate the worm's daily activity cycle, saying "We think they are related to circadian rhythms. We have found that there is a direct connection to the area used for locomotion... In the beginning we had a toolbox... what was in the brain in the worm ends up in our eye." If the animal had two copies of the genes needed to make one kind of photoreceptor, speculates Wittbrodt, then the extra set would have been free to evolve into the other photoreceptor. Different animals would subsequently evolve to use the two options in different ways.
Science fiction authors do not have the constraints of being able to use only Earth DNA; they are free to imagine light-sensing cells in wildly different ways. Here is a small sample of the variety found in sf:
Update: Added item.
They were on a gallery high above a large circular chamber, perhaps a hundred meters across...
It was lifeless... staring up at him. It filled almost all that great circular space, and the ruby light gleamed and shifted in its crystal depths.
It was a single giant eye.
From the Overlord's description, Jan built up a picture of a cyclopean beast living among the asteroidal rubble of some distant sun, its growth uninhibited by gravity, depending for food and life upon the resolving power of its single eye.
From Childhood's End by Arthur C. Clarke.
His sense organs were gathered in clusters at the site of a man's ears; his visage... was corrugated muscle, not dissimilar to the look of the uncovered human brain.
The Meks from The Last Castle by Jack Vance
Facing him from the middle of the room was something neither human nor
humanoid. It stood on three legs, and it regarded Louis Wu from
two directions, from two flat heads mounted on flexible, slender necks.
Over most of its startling frame, the skin was white and glovesoft; but
a thick, coarse brown mane ran from between the beasts necks, back along
its spine, to cover the complex-looking hip joint of the hind leg. The
two forelegs were set wide apart, so that the beast's small, clawed
hooves formed almost an equilateral triangle.
Louis guessed that the thing was an alien animal. In those flat
heads there would be no room for brains. But he noticed the hump that
rose between the bases of the necks, where the mane became a thick
protective mop... and a memory floated up from eighteen decades behind him.
This was a puppeteer, a Pierson's puppeteer. Its brain and skull
were under the hump. It was not an animal; it was at least as intelligent as
a man. And its eyes, one to a head in deep bone sockets, stared fixedly
at Louis Wu from two directions.
The Puppeteers from Ringworld by Larry Niven
"Its body architecture has been redesigned for greater efficiency, our useless simian hangovers have been left out, and its organs have been rearranged in a more sensible fashion...You can't say its not human, for it is .. an improved model. Take that extra appendage at the wrist. That's another hand, a miniature one... backed up by a microscopic eye. You can see how useful that would be, once you get used to the idea..."
The genetically-modified humans from Methuselah's Children by Robert Heinlein
Do you have a favorite alien eye structure? Leave a comment below. See the original article here.
Scroll down for more stories in the same category. (Story submitted 11/3/2004)
Follow this kind of news @Technovelgy.
| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
you like to contribute a story tip?
Get the URL of the story, and the related sf author, and add
Comment/Join discussion ( 3 )
Related News Stories -
Baubotanik - Construction Botany - Builds Bridges
'A dwelling must be all of a unit—the walls, the drainage, the decor grown in!' - Jack Vance, 1954.
Mice Gestate In Mechanical Womb
'... in the Decanting Room, the newly-unbottled babes uttered their first yell of horror and amazement.' - Aldous Huxley, 1932.
Worlds With Underground Oceans More Conducive To Life
'There is life on Europa.' - Arthur C. Clarke, 1982.
Monkey Gets A Bigger Brain, Thanks To Human Gene
'It's a madhouse! a madhouse!' - Planet of the Apes, 1968.
Technovelgy (that's tech-novel-gee!)
is devoted to the creative science inventions and ideas of sf authors. Look for
the Invention Category that interests
you, the Glossary, the Invention
Timeline, or see what's New.
CyberOne Robot By Xiaomi vs. Optimus Robot By Tesla
'I shall introduce myself... I am a robot.'
Giving Snakes Their Legs Back
Then some unknown race had chanced upon the dreamers and decided to 'help them out.'
'Ring Nation' Show Predicted By William Gibson In 1999
'... you had your trademark Lucky Dragon Global Interactive Video Column outside.'
SolarXOne Solar-Powered Drone Flies (almost) Forever
'It's an Indian Air Force drone; its solar cells could power an entire farm.'
Video! Chess Robot Breaks Opponent's Finger In Match
'A robot may not injure a human being.'
Virtual Co-Embodyment - Two People Control One Virtual Body
'... we were supposed to be forming five unit composites first."
The Wanderer: Eyebot From Fallout, Eye From Zelazny
'We send our eyes on their appointed rounds, and they can hover or soar or back up...'
Experts Decry Planet-Scale Schemes To Limit Global Heating
'Light from the sun hit those little spheres and bounced.'
OrganEx Revives The Organs In Dead Pig
'Wakened into half-life activity one hour a month...'
NAVER Labs Haptic Device 2.0 Robot vs. IKEA
'... the two pairs of waldoes in the screen followed in exact, simultaneous parallelism.'
Spaceships Should Last So Long
'THE SPACE VESSEL was traveling swiftly… For over five thousand years they had Voyaged on and on.’
Shine On, Portable Wind Turbine
'Sometimes a man has a windmill on his roof...'
Amazing Indoor Robotic Drones Mimic Dolphins and Whales
'They circled the vast audiences, dancing, twittering, chirping...'
Space Station Shutters
'The sun-quilt was a patchwork of colors and materials on the inward side, but silvered on the outward side...'
Tiny Mining - Extract Precious Industrial Minerals From Your Own Body
'Jim, I saw them reduce four of my doctors and nurses into those little cubes!'
MIT Proposes Space Bubbles To Combat Climate Change, Misses The Point Of Space Bubbles
'Fats Jordan was hanging in the center of the Big Glass Balloon, hugging his guitar to his massive black belly above his purple shorts..'
More SF in the News Stories
More Beyond Technovelgy science news stories