One of the great unanswered questions is how did life arise. Since so many of life’s functions involve chemical interactions on a microscopic scale, it’s a good guess that chemistry was involved from the beginning. No one knows exactly how, but nature left an open door for the inanimate to become animate.
Likely that door is closed now on planet Earth; any living form that might spontaneously arise through chemistry today would probably be eaten by the hordes of animate beings whose ancestors took charge long ago.
In a bit of research that sheds light on how life’s precursor chemicals formed, a team of scientists at the University of Leeds in England examined how meteorites may have contributed one of the key elements that allowed life to literally “power up” – phosphorus.
Meteorite phosphorus is very reactive, meaning it likes to combine with other elements and molecules to form a variety of compounds.
We touched on phosphorus last month after Curiosity discovered the element in an ancient stream bed on Mars. It’s a key ingredient in the hereditary molecule DNA shared by virtually all living organisms and ATP (adenosine triphosphate), a chemical used to store and transport energy in cells.
DNA is to heredity what ATP is to staying alive. All life on Earth is powered by ATP. Meteorites contain phosphorus in a metallic material called schreibersite, made of iron, nickel and phosphorus. Slice open an iron meteorite and you’re likely to see silvery stripes of schreibersite gleaming back.
Researchers took samples of the Russian iron meteorite Sikhote-Alin that crashed to Earth in 1947 and allowed them to stew in acid taken from the Hveradalur geothermal area in Iceland. The idea here was to simulate conditions on the early, volcanically-active Earth when the number of meteorites raining down on the planet was far greater than what it is today.
The rock was left to react with the acidic fluid in test tubes incubated by the surrounding hot spring for four days, followed by a further 30 days at room temperature. When the homemade “primordial soup” was analyzed, the scientists found pyrophosphite, a cousin molecule of pyrophosphate – the part of ATP responsible for energy transfer.
Scientists think that pyrophosphite may have served as the power sources for what they call “chemical life”, not-quite-alive materials that act in some ways like living things:
“Chemical life would have been the intermediary step between inorganic rock and the very first living biological cell. You could think of chemical life as a machine – a robot, for example, is capable of moving and reacting to surroundings, but it is not alive. With the aid of these primitive batteries, chemicals became organized in such a way as to be capable of more complex behaviour and would have eventually developed into the living biological structures we see today,” said Dr Terry Kee, lead researcher from the University’s School of Chemistry.
The group now plans to build a ‘geological fuel cell’ using minerals and gases common on the early Earth, subject them to different chemicals and see what new chemicals result.
The more we seek the origin of this wonderful thing called life, the more our journey takes us into contributions from outer space. Whether it’s phosphorus from meteorites or water and carbon compounds delivered by comet bombardment, our little planet served as a mixing bowl for a recipe called life.
Article source: Univ. of Leeds