[meteorite-list] Some Scientists Think Humans Descended from Martian Microbes

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Apr 3 20:50:26 2006
Message-ID: <200604030558.k335wFW02498_at_zagami.jpl.nasa.gov>

http://www.palmbeachpost.com/business/content/local_news/epaper/2006/04/03/c1a_MARS_0403.html

Some scientists think humans descended from Martian microbes
By Stacey Singer
Palm Beach Post
April 3, 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."
Received on Mon 03 Apr 2006 01:58:14 AM PDT