Lack of Molybdenum May Have Delayed Life on Earth 89
esocid writes "Scientists from around the world have reconstructed changes in Earth's ancient ocean chemistry during a broad sweep of geological time, from about 2.5 to 0.5 billion years ago. They have discovered that a deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth for nearly 2 billion years. Bacteria cannot fix nitrogen efficiently when they are deprived of molybdenum. And if bacteria can't fix nitrogen fast enough, then eukaryotes — a kind of organism that includes plants, pachyderms and people — are in trouble because eukaryotes cannot fix nitrogen themselves at all. Ariel Anbar, a co-author of the research of Arizona State University, stated that "eukaryotes depend on bacteria having an easy enough time fixing nitrogen that there's enough to go around. So if bacteria were struggling to get enough molybdenum, there probably wouldn't have been enough fixed nitrogen for eukaryotes to flourish.""
terraforming and other things (Score:5, Interesting)
Also, this makes me wonder what those eukaryotes were doing for the first 2 billion years. Were they undergoing all sorts of genetic mutations that primed them for takeover once the situation changed? IOW, I wonder what would have happened if this little molybdenum problem had resolved earlier. Would the eukaryotes continued to flounder (pun!) because of a lack of genetic diversity? Or would they have just as rapidly developed putting the current day well into the cockroaches-rule-the-earth epoch?
Interesting thought for a sci-fi novel (Score:1, Interesting)
Maybe we're the last man standing. Call it "The Meek Shall Inherit" or something.
Re:Interesting thought for a sci-fi novel (Score:5, Interesting)
"Centuries ago, sailors on long voyages used to leave a pair of pigs on every deserted island. Or they'd leave a pair of goats. Either way, on any future visit, the island would be a source of meat. These islands, they were pristine. These were home to breeds of birds with no natural predators. Breeds of birds that lived nowhere else on earth. The plants there, without enemies they evolved without thorns or poisons. Without predators and enemies, these islands, they were paradise. The sailors, the next time they visited these islands, the only things still there would be herds of goats or pigs.
Re:Excitement (Score:3, Interesting)
Re:terraforming and other things (Score:3, Interesting)
I did. and molybdenum was not mentioned anywhere.
Re:terraforming and other things (Score:5, Interesting)
It's all about evolution. Sure, you* have enough NH3 to survive, even to grow, but there's millions of tons of N2 gas in the atmosphere, and if you could somehow use that as a fuel source, you'd be set for life.
So then, along comes a random mutation in an enzyme that pulls converts nitrites to nitrates (I'm making this up - but it was probably some enzyme to do with N). Rather than killing you, it allows you to pull N2 out of the air and turn it into ammonia, allowing you to reproduce more quickly. Now another mutation comes along, and it allows you to use Mo to push forward the reaction (mind you it worked before you had Mo: reactions can generally go forward without their cofactors, just more slowly.)
With this cofactor, you're able to reproduce much more quickly than your neighbors which don't have the mutation, and you become the bacteria we know today.
*you here refers to a now-extinct progenitor of nitrogen fixing bacteria. Individuals reproduce, populations evolve.
Like I said, cofactors generally speed up a process. They are not generally required for the reaction to happen, they just speed it up (by several orders of magnitude) when they are present.
Author needs to study some biochemistry (Score:4, Interesting)
Nitrogenase, the enzyme that performs nitrogen fixation today, commonly uses, but doesn't require, molybdenum for its function. There are forms of the enzyme that use vanadium or iron as a cofactor to the ubiquitous iron-sulfur cluster that actually performs the chemistry.
I don't know if this event happened before or after the iron catastrophe, but the fact that the enzyme uses iron anyway makes me believe that there must have been enough iron around the oceans back then. Methinks the author's running off the old idea that the nitrogen reduction occurs on the molybdenum atom instead of one of the iron atoms in the iron-sulfur cluster.
Re:model T (Score:3, Interesting)
cheap energy won't die completely for another hundred years, but cheap oil is already coming to an end... the most likely situation is that we will find ways of turning vast tracks of land into genuine cheap biofuels... the roman empire collapsed when they couldn't grow enough wheat to feed everyone even with slavery and large armies... the question is if the 'modern' world can survive when all our energy has to come from plants, and animals, and the associated costs related to growing enough plants and animals.
it's questionable if humans can manage to maintain large empires the likes of the modern world with 'expensive' bio-energy. after all we can't even stop India from turning into a desert from the mass deforestation going on there.
75% of India is undergoing desertification similar to what privative man did to the middle-east with plows and wheat.
sad really... brazil from all the deforestation well, the amazon river is down 100 feet in places... and rain forests around the world (except in costa rica, which has a healthy tourism industry) are being felled for farms, for fuel, or purely for greed for the hardwoods and softwoods they can grow there. and the farms don't replace the lost precipitation those rain forests used to reciprocate with, while allowing the ground to absorb more of the rain because of the foliage of an old growth or even a new growth forest.
humans would probably turn the whole world to desert if they could, and cutting down all the forests is a good first start for that happening, as is evidenced by india's desertification.