Journal Express, Knoxville, IA

CNHI/SE Iowa

September 3, 2013

Are we Martians after all?

If you looked in a mirror this morning, you may have seen a descendant of creatures from Mars. That is, if biochemist Steven Benner of the Westheimer Institute of Science and Technology in Gainesville, Florida, is right. "Life started on Mars and came to Earth on a rock," Benner declares. Today, at the European Association of Geochemistry's Goldschmidt Conference in Florence, Italy, Benner made what many in the origin-of-life debate call an interesting, but not convincing, new case for our martian heritage.

However and wherever life began, one thing is sure: Its first organic building blocks, called hydrocarbons, had a number of hurdles to clear before evolving into living cells. Fed with heat or light and left to themselves, hydrocarbons tend to turn into useless tarlike substances. And even when complex molecules like RNA (most biologists' best guess for the first genetic molecule) arise, water quickly breaks them down again.

Benner argues that those chemical hurdles would have been lower on early Mars than on young Earth. To begin with, early Earth was probably a water world, completely covered by oceans, but water covered only parts of Mars's surface. Moreover, he notes, rocks on Mars had a stronger oxidizing effect than rocks on Earth, so oxygen-bearing molecules would have formed more easily there. "This is established by observations today on both planets, as well as by models for how planets form," he says.

As a result, molybdates-molecules that contain molybdenum and oxygen-could have existed on Mars, but probably not on Earth. Like oxidized boron (which occurs in dry regions and would also have been rare on a water-covered early Earth), molybdates tend to prevent organic materials from turning into tar. Benner says laboratory experiments show that molybdates can convert certain organic molecules into ribose-an important component of DNA. "This is a fact," he says.

That would make it more likely that life originated on our planetary neighbor, Benner says. Martian microorganisms could have reached Earth on meteorites, flung away from the Red Planet's surface by cosmic impacts.

Benner's hypothesis "is a neat idea, but not yet proven," says biochemist William Bains of the Massachusetts Institute of Technology in Cambridge. Some theories for the origin of life do not need molybdenum at all, Bains says, and scientists don't know for sure whether early Earth was completely covered in water while early Mars was not.

Astrobiologist Paul Davies of Arizona State University, Tempe, agrees that Benner's argument "greatly strengthens the case" for Mars as the first home of terrestrial life. But, he adds, "It comes down to probabilities. The case is suggestive but not overwhelming." Even if early life existed on Mars, he says, it would be hard to prove that those life forms planted the seeds of our own existence. "In fact, because the traffic of [meteoritic] material between Earth and Mars is so prolific, once life gets going on one it will be transferred to the other very quickly, making the place of origin almost impossible to discern."

Astrochemist Pascale Ehrenfreund of George Washington University in Washington, is a bit more optimistic about resolving the issue. Laboratory experiments under conditions that resemble early Mars might lead to realistic answers, she says. But she doesn't find Benner's "interesting idea" convincing.

Benner himself concedes that scientists may never know how and where life emerged. "We will likely need to be satisfied with answers to a more indirect question: How might life have emerged?" Finding martian life, either extant or extinct, could help by revealing information about ancient martian biochemistry. "This could lead to an 'Aha!' moment that opens new thinking relevant to the historical question."

        

1
Text Only
CNHI/SE Iowa
  • 072214 Diamond Llama 1.jpg Llama on the loose corralled in Missouri town

    A llama on the lam cruised Main Street Tuesday before it mistook a resident’s fenced backyard for a place to grab a meal and freshen up.

    July 22, 2014 2 Photos

  • An oncologist uses scorpion venom to locate cancer cells

    Olson, a pediatric oncologist and research scientist in Seattle, has developed a compound he calls Tumor Paint. When injected into a cancer patient, it seems to light up all the malignant cells so surgeons can easily locate and excise them.

    July 22, 2014

  • Screen Shot 2014-07-22 at 2.00.42 PM.png VIDEO: Train collides with semi truck carrying lighter fluid

    A truck driver from Washington is fortunate to be alive after driving his semi onto a set of tracks near Somerset, Ky., and being struck by a locomotive, which ignited his load of charcoal lighter fluid.

    July 22, 2014 1 Photo

  • mama.jpg What we get wrong about millennials living at home

    If the media is to be believed, America is facing a major crisis. "Kids," some age 25, 26, or even 30 years old, are living out of their childhood bedrooms and basements at alarmingly high numbers. The hand-wringing overlooks one problem: It's all overblown.

    July 22, 2014 1 Photo

  • Wal-Mart to cut prices more aggressively in back-to-school push

    Wal-Mart Stores plans to cut prices more aggressively during this year's back-to-school season and will add inventory to its online store as the chain battles retailers for student spending.

    July 21, 2014

  • Hospitals let patients schedule ER visits

    Three times within a week, 34-year-old Michael Granillo went to the emergency room at Northridge Hospital Medical Center in Los Angeles because of intense back pain. Each time, Granillo, who didn't have insurance, stayed for less than an hour before leaving without being seen by a doctor.

    July 21, 2014

  • Starved Pennsylvania 7-year-old weighed only 25 pounds

    A 7-year-old Pennsylvania boy authorities described as being so underweight he looked like a human skeleton has been released from the hospital.

    July 21, 2014

  • Fundraiser for soldiers' families approaching

    CENTERVILLE — Justin Zaputil remembers when Master Sgt. Travis Riddick died. The common reactions didn’t feel right. Mourning and then moving on left something undone. It didn’t seem to accomplish what Zaputil and a handful of others wanted. It didn’

    July 21, 2014

  • Malaysians wonder 'Why us?' after second loss of airline jet

    It was all too familiar. Grieving families rushing to airport. The flashing television graphics of a plane's last radar appearance. The uncomfortable officials before a heavy thicket of microphones.
    For many Malaysians, the disappearance of Flight 370 in March has been a long trauma from which the nation has not yet recovered.

    July 18, 2014

  • A quarter of the world's most educated people live in the 100 largest cities

    College graduates are increasingly sorting themselves into high-cost, high-amenity cities such as Washington, New York, Boston and San Francisco, a phenomenon that threatens to segregate us across the country by education.

    July 18, 2014

Features
AP Video
NYPD Chief Calls for 'use of Force' Retraining VA Nominee McDonald Goes Before Congress Airlines Halt Travel to Israel Amid Violence Airlines Halt Travel to Israel Amid Violence US Official: Most Migrant Children to Be Removed Police Probing Brooklyn Bridge Flag Switch CDC Head Concerned About a Post-antibiotic Era Raw: First Lady Says `Drink Up' More Water Raw: Massive Fire Burns in North Dakota Town Raw: Truck, Train Crash Leads to Fireball Courts Conflicted Over Healthcare Law Holder Urges Bipartisanship on Immigration US Airlines Cancel Israel Flights Obama Signs Workforce Training Law Obama Offers Condolences at Dutch Embassy Michigan Plant's Goal: Flower and Die WWII Vet Gets Medals, 70 Years Late Weather Gives Washington Firefighters Hope Veteran Creates Job During High Unemployment Widow: Jury Sent Big Tobacco a $23B Message
Facebook
Hyperlocal Search
Premier Guide
Find a business

Walking Fingers
Maps, Menus, Store hours, Coupons, and more...
Premier Guide
Poll

Upon completion and reopening of Third Street, should the City of Knoxville wait to start the next stage of the Streetscape and Infrastructure project until 2015?

Yes
No
     View Results