Early Earth Was Purple, Study Suggests (Go Vikes!)

LiveScience.com on yahoo ^ | 4/10/07 | Ker Than

[NormsRevenge]

The earliest life on Earth might have been just as purple as it is green today, a scientist claims.

Ancient microbes might have used a molecule other than chlorophyll to harness the Sun’s rays, one that gave the organisms a violet hue.

Chlorophyll, the main photosynthetic pigment of plants, absorbs mainly blue and red wavelengths from the Sun and reflects green ones, and it is this reflected light that gives plants their leafy color. This fact puzzles some biologists because the sun transmits most of its energy in the green part of the visible spectrum.

“Why would chlorophyll have this dip in the area that has the most energy?” said Shil DasSarma, a microbial geneticist at the University of Maryland.

...

Possible answer

DasSarma thinks it is because chlorophyll appeared after another light-sensitive molecule called retinal was already present on early Earth. Retinal, today found in the plum-colored membrane of a photosynthetic microbe called halobacteria, absorbs green light and reflects back red and violet light, the combination of which appears purple.

Primitive microbes that used retinal to harness the sun’s energy might have dominated early Earth, DasSarma said, thus tinting some of the first biological hotspots on the planet a distinctive purple color.

Being latecomers, microbes that used chlorophyll could not compete directly with those utilizing retinal, but they survived by evolving the ability to absorb the very wavelengths retinal did not use, DasSarma said.

...

Chlorophyll more efficient

The researchers speculate that chlorophyll- and retinal-based organisms coexisted for a time. “You can imagine a situation where photosynthesis is going on just beneath a layer of purple membrane-containing organisms,” DasSarma told LiveScience.

[antiRepublicrat]

Does he think that the "un-utilized" photons were just rolling around on the ground, waiting for plants with chlorophyll to scoop them up?

I think he's saying that since one class of life was all over the place and absorbing one set of the light spectrum, instead of competing another grew to absorb a different set of the spectrum.

Isn't there a reverse of this, a "green window" effect?

[martin_fierro]

Early Earth Was Purple, Study Suggests (Go Vikes!)

Apparently it was also Defenseless.

[mmichaels1970]

Early Earth Was Purple, Study Suggests (Go Vikes!)

And it ended up losing in the end.

[lesser_satan]

Early Earth Was Purple, Study Suggests (Go Vikes!)

That was back in the days of Bud Grant and Burnsy. Then Denny came along and ruined it all.

[Redcloak]

But that doesn't make any sense. If plant A is over here absorbing light between 600 and 700 nm, plant B in some other location, also absorbing light in that band, isn't affected at all. They don't compete. The plants that used retinal didn't suck up all the light in that particular spectrum.

Plants compete for light by growing taller and getting out of shade cast by other plants. Being short, but using a different spectrum of light doesn't help a plant; it's still in the dark.

[49th]

However, when both types of plants are located in the same area, and lets say that this area it does make sense for one type of plant to absorb a different section of the spectrum. Growing taller isn’t the only way that plants compete with each other for light, it’s merely the most readily apparent.

[metmom]

Okaaaaayyyy.

[null and void]

Speaking as an optical engineer, that's the stupidest thing I've read in a long time. Does he think that the "un-utilized" photons were just rolling around on the ground, waiting for plants with chlorophyll to scoop them up?

No. But the green wasn't available because it was being sucked up by the retinal. A soup of purple (brown algae?) bacteria, would act like a band reject filter for greens, with lots of red and blue available.

You were assuming big plants, not the single cell stuff that drives new divisions.

[JRios1968]

This guy was happy to hear the news...

[SunkenCiv]

Steep oxygen decline halted first land colonization by Earth’s sea creatures
EurekAlert | Monday, October 23, 2006 | University of Washington
Posted on 10/25/2006 1:21:07 AM EDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1725406/posts

[SunkenCiv]

Didn't check, but this link is probably good and dead.

Earth's Oxygen Enigma
by Kathy A. Svitil
February 11, 2003
Carrine Blank of Washington University in St. Louis

Scientists have long believed that blue-green algae arose 3.5 billion years ago, pumping out oxygen and causing the oceans to fill with rust. Over the next billion years the algae transformed Earth's atmosphere, allowing oxygen-breathing life to evolve. Carrine Blank of Washington University in St. Louis... compared genetic sequences from 53 different groups of bacteria -- including blue-green algae, also known as cyanobacteria -- to construct a detailed family tree. The results confounded her expectations. "Cyanobacteria arose fairly late, about 2.2 or 2.3 billion years ago. That explains why we see this very sudden increase in oxygen, around 2.2 to 2 billion years ago, which has always been a big mystery," she says. The finding implies that something else caused the ocean rusting.

[grey_whiskers]

Early Earth Was Purple, Study Suggests (Go Vikes!)

Apparently it was also Defenseless.

Ah, yes.

But don't forget the great receiving corps (for absorbing photons...)

...and the mass extinctions would be every time Earth made the playoffs.

(Oh, well, there's always the Twins.)

Cheers!

[antiRepublicrat]

Plants compete for light by growing taller and getting out of shade cast by other plants. Being short, but using a different spectrum of light doesn't help a plant; it's still in the dark.

I think the idea here is that the microbes were everywhere, coating most things, and blocked only green light from going through. I don't think they have any real evidence for this, but it seems plausible to me. Interesting idea.