Blogs / 80beats

The evolution of minerals on our planet has been propelled by the evolution of life on earth, a sweeping new study demonstrates. While the underlying assumption isn’t new, the study is the first to chart how the emergence of algae and then complex microorganisms gave rise to the 4,300 or so minerals that are now present on earth.

In the early days of the universe, clouds of gas and dust contained all the naturally occurring elements found in the periodic table, but most were too widely dispersed to form minerals; scientists believe there were only about a dozen minerals in the interstellar medium. According to the study, around a further 60 different minerals formed 4.5 billion years ago, as clumps of matter collided and coalesced to begin forming the Solar System. The smaller fragments congealed into larger, planet-sized bodies, where volcanism and the effects of water took the mineral count into the hundreds. The planets Mars and Venus have got this far [Nature News], and have minerals created by hot magma like quartz and zircon.

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Vials holding the results of a famous chemistry experiment conducted 55 years ago have been discovered in dusty cardboard boxes, and a new analysis of their contents has revealed fresh insights into a big question: the origin of life on earth. In 1953, chemist Stanley Miller tried to duplicate the conditions present on the primordial earth in laboratory flasks, and while some of his results were published to great acclaim, other results were packed away and forgotten–until now.

Miller’s classic experiment involved putting atmospheric components thought to reflect those of the early Earth (ammonia, hydrogen, methane, and water) in a closed system and stimulating that mixture with an electric current to mimic the effects of lightning storms. He generated a small number of biochemically significant compounds, including amino acids, hydroxy acids, and urea, showing that conditions of primitive earth can create the building blocks of life [Ars Technica]. These results generated considerable excitement, but later researchers argued that Miller was wrong about the composition of the young earth’s atmosphere, and the experiment was written off as a novelty.

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In the middle of the Australian outback along a mountain chain called the Flinders Ranges, researchers have discovered a 650 million year old reef that was once underwater. Researchers say the tiny fossils they’ve already found in the ancient reef may be the earliest examples of multicellular organisms ever found, and may answer questions about how animal life evolved.

Researcher Malcolm Wallace explains that the oldest-known animal fossils are 570 million years old. The reef in the Flinders Ranges is 80 million years older than that and was, he said, “the right age to capture the precursors to animals” [The Times]. The first fossils discovered in the reef appear to be sponge-like multicellular organisms that resemble tiny cauliflowers, measuring less than an inch in diameter, but Wallace cautions that the creatures haven’t been thoroughly studied yet. The reef’s discovery was announced at a meeting of the Geological Society of Australia this week.

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In a salty hot spring near Mono Lake, California, researchers have found two new species of bacteria that use arsenic for photosynthesis, and require no oxygen to fuel the process. Researchers say the bacteria may be similar to those that existed on primordial Earth where oxygen was scarce, and may illustrate an important stage of how early life developed in mineral-rich waters over 2 billion years ago.

Arsenic is well-known for its toxicity; it was used so often as tool for homicide in the 1800s that it earned the nickname “king of poisons” [The Scientist]. Yet the newly discovered bacteria can not only tolerate the element, they require it to survive. One of the first steps most organisms perform in photosynthesis is to split water molecules, creating oxygen. Oxygen donates energy in the form of electrons to other molecules, setting off a chain reaction that eventually results in the building of sugars for the organism’s own food. For the red and green bacteria found in Mono Lake, arsenic plays the role of oxygen [Science News].

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Researchers say that diamond fragments from the dawn of time may contain evidence that life began on Earth as early as 4.25 billion years ago, just a few hundred million years after the planet came into existence–although they also say that their findings aren’t conclusive and that they may well be wrong.

Studying anything about the ancient earth is extremely difficult. Rocks that formed four billion years ago will long since have been beat up, metamorphosed, or melted [Nobel Intent blog, Ars Technica]. Researchers got around that problem by studying microscopic diamond pieces inside zircon crystals, which are themselves the tough remnants of ancient rocks that have long since disappeared. “We don’t have the rocks. These zircons are just little fragments of something that was broken up, weathered and redeposited as sediments,” explained [coauthor Martin] Whitehouse [BBC News].

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