The Miracle of Life on Earth: How We Breathe

By Shlomo Maital  

      The latest Science Friday podcast features a book by Stephen Porder, Elemental, showing how life on earth – ALL life on earth – is built on five elements:  Oxygen, nitrogen, carbon, hydrogen, and phosphorus, and describes how it all evolved.

       You have to admit it – it is all truly amazing, even miraculous. 

      STEPHEN PORDER: [1]  We are in the middle of really existential environmental anxiety. Sometimes it feels like what we’re doing is so bizarre and abnormal and impossible to solve that it engenders despair.  What we can learn from the commonalities we have with other organisms that have changed the world can help us think clearly and shape a more sustainable future.

     “We’re all made of the same stuff — hydrogen, oxygen, carbon, nitrogen and phosphorus.  They play a really critical role in determining the climate and environmental conditions on the planet.

   “When organisms evolve a new way of getting these elements, they have the capacity to change the world.   The cyanobacteria– this is a story that is deep in the Earth’s past– so 2.5 billion years ago, which is about halfway through Earth’s history– and these organisms figure out evolutionarily a way to get better access to carbon.  [cyanobacteria are blue (hence the name), and get energy through photosynthesis.]

      “They evolve a new way of doing photosynthesis that is much more efficient. So they get this great energy source. They use the sunlight more efficiently.   And they also evolve a way to get access to nitrogen, which allows them to build more machinery to capture even more sunlight. And together, those two processes allow them to wildly proliferate across the planet. 

     “But as a byproduct of their chemistry, they spill a pollutant out into the atmosphere. And that pollutant is oxygen. The oxygen that we breathe, that all multicellular life depends on, it wouldn’t be here if it weren’t for the cyanobacteria accidentally polluting the planet.

     “They probably caused the biggest environmental change of all time.    Cyanobacteria come along. And they’re so successful that they pump enough oxygen into the air that two things happen. One, all the organisms that are used to there being no oxygen around are all of a sudden faced with competition from organisms that are using oxygen.

    “And two, the oxygen bubbles out of the oceans and reacts with all that methane that was keeping the planet unfrozen. And we actually precipitate a global, we think, glaciation. Because the waste product of the cyanobacteria changes the global greenhouse. So it’s unintended catastrophe that follows this wild proliferation and evolutionary success, for lack of a better word.”

. . . . .

    OK, so – we get the oxygen we breathe, from cyanobacteria – but as oxygen replaces methane, we get a global frigid Ice Age – so, that’s bad.  Right?

    Not really.   Large Ice Age animals shaped humans into fierce hunters. When the climate changed and those animals increasingly died off, new land became available, and new climate patterns set the ground for the Agricultural Revolution to take place shortly after the Ice Age ended. The Agricultural Revolution was the dawn of large and settled populations and the rise of ancient civilization.

    Life on earth is truly a miracle – a tale of ups and downs.  If we in a down, there will be an eventual up.

[1]   Stephen Porder   Elemental: How Five Elements Changed Earth’s Past and Will Shape Our Future.