#Some scientists think humans descended from Martian microbes

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Some scientists think humans descended from

Martian microbes

 

By Stacey Singer

 

Palm Beach Post Staff Writer

 

Monday, April 03, 2006

 

Astrobiology sounds like the stuff of lava lamps

and Jetsons reruns.

 

Yet seven years after NASA launched a formal

astrobiology research

program, scientists of every stripe — geologists,

biologists, chemists,

paleontologists, oceanographers and astronomers —

have rallied to the quest.

 

They've spent as much as $65 million a year

trying to solve a mystery

that has underpinned religion and inspired

thinkers from Seneca to Carl

Sagan: How did life on the lonely Earth begin?

And is Earth really the

only source of life in the universe?

 

With the help of modern tools such as the genome,

high-powered computer

modeling and robotics, they're finding some

out-of-this-world answers,

ones that may lead to Mars and beyond.

 

During an astrobiology conference in Washington

last week, scientists

debated the newest evidence and worried that

funding for the National

Aeronautics and Space Administration is

vaporizing, just as their

cross-disciplinary work is unearthing

extraordinary discoveries, such as

the organic matter in bits of Jovian comet dust

recently collected by

NASA's Stardust probe.

 

Many scientists favor the theory that life began

as oxygen-loathing

microbes in superheated deep-sea vents 3.8

billion years ago, when water

probably covered the planet. Others suggest

life's assembly could have

occurred along the crystal face of damp volcanic

rock.

 

And then there is the theory known as panspermia.

Once the province of

science-fiction novels and cartoons, the notion

that the vital

ingredients of life came from outer space has

garnered respect from some

lofty places of late.

 

A few scientists think there's evidence that

humans actually descended

from Martian microbes, not exactly what the

author of Men are from Mars,

Women are from Venus had in mind.

 

But it merits further study, said chemist Steven

Benner, who has founded

a new institute in Gainesville, the Westheimer

Institute for Science and

Technology, which aims to bridge chemistry and

biology, with evolution

as its guide.

 

" If you really want to find a place to get life

started, it's Mars, and

if you want to get a place to get life to

flourish, it's Earth, " Benner

said.

 

While at the University of Florida a few years

ago, Benner's team

collaborated with scientists at The Scripps

Research Institute to

explore what kind of chemistry is necessary to

support life.

 

In the process of trying to synthesize a living,

evolving molecule in

his lab, Benner seized upon minerals containing

the element boron, the

substance that makes some fireworks glow green.

 

Was boron the ingredient that enabled the Earth

to go green as well?

 

Benner found that boron, with calcium at hand,

had the talent of helping

hold together the chain of carbon needed to

stabilize a ribose sugar,

the backbone of ribonucleic acid, the scaffolding

for our genes. Without

boron and calcium, heat, water and lightning

would cause ribose to

disintegrate into a tarlike mess, unable to

support genes.

 

For geologic reasons, Benner's boron finding

points directly to Mars as

a likely source for Earth life, said Cal Tech

geobiologist Joseph L.

Kirschvink.

 

" When Steve told me of his work on ribosynthesis

with boron, I said,

'Steve you've just proven to me that we're

Martians.' "

 

That's because the boron needed to make ribose

must come as calcium

borate, a mineral that's soluble in water,

Kirschvink believes.

 

A few places on Earth, including Death Valley,

have a good supply of

calcium borate, but they were under water at the

time the first evidence

of microbes appears on Earth, Kirschvink said.

That was not the case on

Earth's nearest neighbor, Mars, which was sending

off bits of rock and

dust in the Earth's general direction every time

it took a hit from a

meteorite.

 

" We know we have about a ton of Martian rock

coming in a year, "

Kirschvink said. " And it wouldn't take more than

a few spores to seed

the Earth with life. "

 

Could Mars possibly have had spores?

 

Space exploration and powerful telescopes have

revealed that the red

planet has polar ice, just like our own planet.

In 2004, NASA's

Opportunity rover found evidence that it once had

liquid water running

across its surface.

 

And 3 billion or 4 billion years ago, at the time

when the Earth

apparently was covered with water, Mars may have

had a warmer atmosphere

and abundant microbial life.

 

" It's entirely reasonable that there was life on

Mars, but maybe long

extinct, " said Gerald Joyce, a professor at

Scripps in La Jolla, Calif.,

who has collaborated with Benner. " The way to

find it is to go there,

drill down a bit, bring back samples to Earth and

look at them. "

 

Unfortunately, a plan to do just that has fallen

victim to NASA budget cuts.

 

" It's very sad, " Joyce said.

 

Plus, President Bush's budget request to Congress

for next year proposes

slashing funding for astrobiology research in

half.

 

Kirschvink fears religious sentiment may be

playing a role in the money

cuts.

 

" There are fundamentalists who don't like the

idea that their creator

put life anywhere other than Earth, " he said.

 

In the meantime, Joyce and other scientists are

going as far as they

possibly can with their science here on Earth.

 

In the journal Chemistry & Biology, Joyce's lab

describes using

evolutionary principles to convert RNA into DNA

and keep its chemical

activity intact.

 

Such conversion may have been necessary for more

advanced life to

evolve. It's one more clue as to how life might

have assembled, Joyce said.

 

Meanwhile, the Marsophiles are excited about a

new paper from Martin

Fisk, a University of Oregon marine geologist.

Fisk has studied several

pieces of Martian meteorite, including one called

Nakhla, donated from

the Smithsonian Institution. In the journal

Astrobiology, Fisk describes

finding tunnels etched into the Martian rock —

tunnels just like ones he

has seen in Earth rock. On Earth, only microbes

cause those types of

tunnels.

 

" They are not known to be made by any other

process that we know of, "

Fisk said.

 

It's a controversial notion, one that has been

debated since 1996, when

another bit of Martian meteorite stored at NASA

labs near Houston was

found to contain organic material and what

appeared to be fossilized

microbes.

 

At the time, critics shot down the idea,

insisting that inorganic

activity might have made the marks in the rock.

 

Fisk notes that his samples contained no DNA, the

code for life.

 

Benner thinks it's not a deal-breaker.

 

" The failure to find DNA in the Martian rock is

assumed to argue against

Martian life. But this logic is coherent only if

Martian life must use

the same type of DNA as Earth life uses, " Benner

said.

 

Kirschvink agreed. " DNA would not survive 4

billion years, even on

Mars, " he said. " It barely survives in frozen

mammoths that are only

12,000 years old. "

 

For now, there are more skeptics of Mars' seeding

life on Earth than

there are advocates.

 

Conel Alexander, a geochemist with the Carnegie

Institution of

Washington, suspects life arose organically on

Earth.

 

" The worry is nobody really understands how well

microbes would survive

the shock that is required to put something into

orbit. To knock it off

Mars, how would it survive the radiation? That's

one of the many

questions, " Alexander said.

 

" Nonsense, " retorts Kirschvink. " The European

Space Agency demonstrated

more than five-year survival to space conditions,

and some of the

Martian meteorites get here within one year of a

major impact on Mars. "

 

Matt Schrenk, a geobiologist at the Carnegie

Institution, favors the

deep-sea vent theory, although he's not ruling

anything out yet.

 

" The simplest explanation is that life started

here, " Schrenk said.

" This is the one place where we know life does

exist on Earth. But I

think as evidenced by this Stardust mission,

there's plenty of organic

material coming in constantly from space. That

must have played some

role in the origin of life on Earth. "

 

--

" Now, by the way, any time you hear the United

States government talking

about wiretap, it requires -- a wiretap requires

a court order. Nothing has

changed, by the way. When we're talking about

chasing down terrorists, we're

talking about getting a court order before we do

so "

-George W. Bush, April 20, 2004

 

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