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Are we all Martians?

Aug. 29, 2013
Courtesy of the European Association of Geochemistry
and World Science staff

New ev­i­dence sup­ports a long-debated the­o­ry that life on Earth may have started on Mars, a sci­ent­ist says.

Chem­ist Ste­ven Ben­ner of the Wes­t­heimer In­sti­tute in Gains­esville, Fla. told geo­chemists at a con­fer­ence Aug. 29 that a min­er­al form of the el­e­ment mo­lyb­de­num, pos­sibly cru­cial to the or­i­gin of life, could only have been avail­a­ble on Mars.

These con­di­tions “may still ex­ist on Mars,” said Ben­ner, form­erly of the the Uni­vers­ity of Flor­i­da.

Only when mo­lyb­de­num be­comes highly ox­i­dized, or com­bined with ox­y­gen, is it “a­ble to in­flu­ence how early life formed,” added Ben­ner. “This form of mo­lyb­de­num could­n’t have been avail­a­ble on Earth at the time life first be­gan, be­cause three bil­lion years ago the sur­face of the Earth had very lit­tle ox­y­gen, but Mars did.”

Life could have reached Earth via a Mar­tian me­te­or­ite, he ar­gued.

Ben­ner spoke at the Gold­schmidt con­fer­ence in Flor­ence, It­a­ly, an event or­gan­ized an­nu­ally through the sup­port of the St. Lou­is, Mo.-based Ge­o­chem­i­cal So­ci­e­ty and the Eu­ro­pe­an As­socia­t­ion for Ge­o­chem­is­try.

The re­search ad­dresses two para­doxes which make it hard for sci­ent­ists to un­der­stand how life could have started. The first is is the “tar para­dox,” Ben­ner said. Liv­ing things are made of or­gan­ic ma­te­ri­al, but if you add en­er­gy such as heat or light to or­gan­ic mol­e­cules and leave them to them­selves, they don’t cre­ate life. In­stead, they turn in­to some­thing more like tar, oil or as­phalt.

“Cer­tain el­e­ments seem able to con­trol the propens­ity of or­gan­ic ma­te­ri­als to turn in­to tar, par­tic­u­larly bo­ron and mo­lyb­de­num, so we be­lieve that min­er­als con­tain­ing both were fun­da­men­tal to life first start­ing,” said Ben­ner. “Anal­y­sis of a Mar­tian me­te­or­ite re­cently showed that there was bo­ron on Mars; we now be­lieve that the ox­i­dized form of mo­lyb­de­num was there too.”

The sec­ond par­a­dox is that life would have strug­gled to start on early Earth be­cause the plan­et was probably to­tally wa­ter-cov­ered, Ben­ner said. This would have pre­vented suf­fi­cient con­centra­t­ions of bo­ron form­ing – it’s cur­rently only found in very dry places like Death Val­ley – and wa­ter cor­rodes RNA, which sci­ent­ists be­lieve was the first ge­net­ic mol­e­cule to ap­pear. 

Al­though there was wa­ter on Mars, it cov­ered much smaller ar­eas than on early Earth.

“The ev­i­dence seems to be build­ing that we are ac­tu­ally all Mar­tians; that life started on Mars and came to Earth on a rock,” said Pro­fes­sor Ben­ner. “It’s lucky that we ended up here nev­er­the­less, as cer­tainly Earth has been the bet­ter of the two plan­ets for sus­tain­ing life. If our hy­po­thet­i­cal Mar­tian an­ces­tors had re­mained on Mars, there might not have been a sto­ry to tell.”


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New evidence supports a long-debated theory that life on Earth may have started on Mars, a scientist said. Chemist Steven Benner of the Westheimer Institute in Gainsesville, Fla. told geochemists at a conference Aug. 29 that a mineral form of the element molybdenum, possibly crucial to the origin of life, could only have been available on Mars. These conditions “may still exist on Mars,” said Benner, formerly of the the University of Florida. Only when molybdenum becomes highly oxidized, or combined with oxygen, is it “able to influence how early life formed,” added Benner. “This form of molybdenum couldn’t have been available on Earth at the time life first began, because three billion years ago the surface of the Earth had very little oxygen, but Mars did.” Life could have reached Earth via a Martian meteorite, he argued. Benner spoke at the Goldschmidt conference in Florence, Italy, an event organized annually through the support of the St. Louis, Mo.-based Geochemical Society and the European Association for Geochemistry. The research addresses two paradoxes which make it hard for scientists to understand how life could have started. The first is is the “tar paradox,” Benner said. Living things are made of organic material, but if you add energy such as heat or light to organic molecules and leave them to themselves, they don’t create life. Instead, they turn into something more like tar, oil or asphalt. “Certain elements seem able to control the propensity of organic materials to turn into tar, particularly boron and molybdenum, so we believe that minerals containing both were fundamental to life first starting,” said Benner. “Analysis of a Martian meteorite recently showed that there was boron on Mars; we now believe that the oxidized form of molybdenum was there too.” The second paradox is that life would have struggled to start on the early Earth because it was likely to have been totally covered by water. Not only would this have prevented sufficient concentrations of boron forming – it’s currently only found in very dry places like Death Valley – but water is corrosive to RNA, which scientists believe was the first genetic molecule to appear. Although there was water on Mars, it covered much smaller areas than on early Earth. “The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock,” said Professor Benner. “It’s lucky that we ended up here nevertheless, as certainly Earth has been the better of the two planets for sustaining life. If our hypothetical Martian ancestors had remained on Mars, there might not have been a story to tell.”