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Searching for the origin of life essay

Subterranean Surprises Hazen, a mineralogist, is investigating how the first organic chemicals—the kind found in living things—formed and then found each other nearly four billion years ago. He began this research in 1996, about two decades after scientists discovered hydrothermal vents—cracks in the deep ocean floor where water is heated to hundreds of degrees Fahrenheit by molten rock.

The vents fuel strange underwater ecosystems inhabited by giant worms, blind shrimp and sulfur-eating bacteria. Hazen and his colleagues believed the complex, high-pressure vent environment—with rich mineral deposits and fissures spewing hot water into cold—might be where life began.

Hazen realized he could use the pressure bomb to test this theory. If something were to go wrong, the ensuing explosion could take out a good part of the lab building; the operator runs the pressure bomb from behind an armored barrier. In his first experiment with the device, Hazen encased a few milligrams of water, an organic chemical called pyruvate and a powder that produces carbon dioxide all in a tiny capsule made of gold which does not react with the chemicals inside that he had welded himself.

He put three capsules into the pressure bomb at 480 degrees and 2,000 atmospheres. And then he went to lunch. When he took the capsules out two hours later, the contents had turned into tens of thousands of different compounds.

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In later experiments, he combined nitrogen, ammonia and other molecules plausibly present on the early earth. In these experiments, Hazen and his colleagues created all sorts of organic molecules, including amino acids and sugars—the stuff of life. Before them, origins-of-life research had been guided by a scenario scripted in 1871 by Charles Darwin himself: Miller set up a container holding water representing the early ocean connected by glass tubes to one containing ammonia, methane and hydrogen—a mixture scientists of the day thought approximated the early atmosphere.

A flame heated the water, sending vapor upward. In the atmosphere flask, electric sparks simulated lightning. But over the next few days, the water turned deep red. Miller had created a broth of amino acids.

His work soon led him to a more surprising conclusion: Cracking open space rocks, astrobiologists have discovered amino acids, compounds similar to sugars and fatty acids, and nucleobases found in RNA and DNA. But NASA, then starting up its astrobiology program, was looking for evidence that life could have evolved in odd environments—such as on other planets or their moons. How did the right building blocks get incorporated? Amino acids come in multiple forms, but only some are used by living things to form proteins.

How did they find each other? In a windowed corner of a lab building at the Carnegie Institution, Hazen is drawing molecules on a notepad and sketching the earliest steps on the road to life. It was probably just a few molecules here and there in a vast ocean.

He thinks that rocks—whether the ore deposits that pile up around hydrothermal vents or those that line a tide pool on the surface—may have been the matchmakers that helped lonely amino acids find each other.

Rocks have texture, whether shiny and smooth or craggy and rough. Molecules on the surface of minerals have texture, too.

An amino acid that drifts near a mineral could be attracted to its surface. Kateryna Klochko is preparing an experiment that—when combined with other experiments and a lot of math—should show how certain molecules stick to minerals. Do they adhere tightly to the mineral, or does a molecule attach in just one place, leaving the rest of it mobile and thereby increasing the chances it will link up to other molecules?

Klochko gets out a rack, plastic tubes and the liquids she needs.

The Origins of Life

She puts a tiny dab of a powdered mineral in a four-inch plastic tube, then adds arginine, an amino acid, and a liquid to adjust the acidity. Then, while a gas bubbles through the solution, she waits. The work may seem tedious indeed, but it takes concentration. After two hours, the samples go into a rotator, a kind of fast Ferris wheel for test tubes, to mix all night. She and other researchers will repeat the same experiment with different minerals and different molecules, over and over in various combinations.

How long will it take to go from studying how molecules interact with minerals to understanding how life began? For one thing, scientists have never settled on a definition of life. Everyone has a general idea of what it is and that self-replication and passing information from generation to generation are key.

  • The joining of those monomers in large chains constitutes the biopolymers;
  • It became an eminently interdisciplinary theme, involving cosmology, astrophysics, planetology, geology, organic chemistry, molecular biology, mathematics and complex systems theory;
  • Thus, instead of a single trunk, the phylogenetic tree might have originated from several separate trunks that ended up connecting themselves in three great branches, which later subdivided into secondary branches;
  • Hazen realized he could use the pressure bomb to test this theory;
  • A 15-million-year-old whale jawbone, discovered on the beach at low tide, is spread out in pieces on the dining room table, where Hazen is cleaning it;
  • This has led to a consensus that hydrogen-rich or at least oxygen-poor conditions were necessary for natural organic syntheses prior to the appearance of life.

Amino acids in your body stick to titanium joints; films of bacteria grow inside pipes; everywhere proteins and minerals meet, amino acids are interacting with crystals. At his weekend retreat overlooking the Chesapeake Bay, Hazen, 61, peers through binoculars at some black-and-white ducks bobbing around in circles and stirring the otherwise still water. He calls for his wife, Margee, to come take a look: A 15-million-year-old whale jawbone, discovered on the beach at low tide, is spread out in pieces on the dining room table, where Hazen is cleaning it.

Hazen traces his interest in prehistory to his Cleveland childhood, growing up not far from a fossil quarry. After his family moved to New Jersey, his eighth-grade science teacher encouraged him to check out the minerals in nearby towns.

They now have thousands. Bob has played trumpet professionally since 1966. But the couple tend not to hold on to things. Harvard has the mineral collection he started in eighth grade, and the Hazens are in the process of donating their trilobites to the National Museum of Natural Searching for the origin of life essay. After considering, for some time, how minerals may have helped life evolve, Hazen is now investigating the other side of the equation: He explains that there were only about a dozen different minerals—including diamonds and graphite—in dust grains that pre-date the solar system.

Another 50 or so formed as the sun ignited. On earth, volcanoes emitted basalt, and plate tectonics made ores of copper, lead and zinc. Mosses and algae climbed onto land, breaking down rock and making clay, which made bigger plants possible, which made deeper soil, and so on.

Today there are about 4,400 known minerals—more than two-thirds of which came into being only because of the way life changed the planet. Some of them were created exclusively by living organisms. Everywhere he looks, Hazen says, he sees the same fascinating process: Stuff gets more complicated. Once life gets a foothold, the fact that the environment is so variable is what drives evolution. Helen Fields has written about snakehead fish and the discovery of soft tissue in dinosaur fossils for Smithsonian.

Amanda Lucidon is based in Washington, D. To mimic conditions for life on early earth, Bob Hazen, in his Carnegie lab, used a "pressure bomb" to heat and compress chemicals. Amanda Lucidon A fossil collector since childhood, Hazen, shown here inspecting ancient seashells on Chesapeake Bay, has come up with new scenarios for life's beginnings on earth billions of years ago. Amanda Lucidon Scientists are searching for life's origins beyond the "warm little pond" that, 140 years ago, Charles Darwin speculated was the starting place.

Kateryna Klochko, in Hazen's lab, combines mineral dust and amino acids, the building blocks of proteins. Amanda Lucidon Some meteorites, shown here is a magnified cross section of one found in Chile, contain amino acids, raising the possibility that life was seeded from space. Amanda Lucidon Despite high temperatures and pressures, deep-sea hydrothermal vents harbor living things. Science Source Hazen began collecting trilobites—extinct marine arthropods like this Paralejurus—when he was a child.

Amanda Lucidon The first organic molecules may have needed rocks to bring them together, says Hazen, with his wife Margee near their Chesapeake Bay weekend retreat. But the relationship goes both ways: Amanda Lucidon Like this article?