One of many chemicals that the scientists of his time thought could only be produced by the Vital Force, acting inside a living creature. The artificial production and urea suggested that life might not be powered by a mysterious force, but instead is powered by normal chemical reactions, which could be studied and understood. Since that time, numerous molecules and cellular activities have been recreated in the lab, clearly demonstrating a life is powered by normal chemical reactions and suggesting that life may have emerged from non-living chemistry. Researchers have recently discovered that many of the building blocks of life, amino acids and sugars, exist inside meteorites, rocks that have fallen to the earth from outer space. This tells us that these special molecules are being produced spontaneously throughout our solar system and may have been common on ancient Earth. We've also discovered a process now referred to as Chemical Evolution. When simple molecules are left alone with an energy source, they interact with one another, often forming larger, more complex molecules as time goes on. Experiments in the lab have shown that chains of chemical reactions can develop, some of which resemble the metabolic pathways of life! Surprisingly, we've also found that certain molecules have the remarkable ability to self-assemble into complex, orderly structures. Some self-assemble into hollow spheres almost identical to the membranes of modern living cells. Others self-assemble into long columns remarkably similar to the strains of DNA found in life. Scientists still have many questions to answer about life's origins: How did different types of the molecules first start working together, eventually producing the genetic code? What were the original reproducing creatures like? Were they similar to the cells we have today? Or were they something much simpler? And finally, possibly the most interesting question of all, how likely is it that life has formed, or is forming, in other regions of are galaxy? So... back to the original question, can science explain the origin of life? Science has not explained the origin of life in full detail, but researchers are building a theory intended to one day describe, Billions of years ago on the young planet Earth simple organic compounds assembled into more complex coalitions that could grow and reproduce. They were the very first life on Earth, and they gave rise to every one of the billions of species that have inhabited our planet since. At the time, Earth was almost completely devoid of what we’d recognize as a suitable environment for living things. The young planet had widespread volcanic activity and an atmosphere that created hostile conditions. So where on Earth could life begin? To begin the search for the cradle of life, it’s important to first understand the necessities for any life form. Elements and compounds essential to life include hydrogen, methane, nitrogen, carbon dioxide, phosphates, and ammonia. For these ingredients to comingle and react with each other, they need a liquid solvent: water. And to grow and reproduce, all life needs a source of energy. Life forms are divided into two camps: autotrophs, like plants, that generate their energy, and heterotrophs, like animals, that consume other organisms for energy. The first life form wouldn’t have had other organisms to consume, of course, so it must have been an autotroph, generating energy either from the sun or from chemical gradients. So what locations meet these criteria? Places on land or close to the surface of the ocean have the advantage of access to sunlight. But at the time when life began, the UV radiation on Earth’s surface was likely too harsh for life to survive there. One set offers protection from this radiation and an alternative energy source: the hydrothermal vents that wind across the ocean floor, covered by kilometers of seawater and bathed in complete darkness. A hydrothermal vent is a fissure in the Earth’s crust where seawater seeps into magma chambers and is ejected back out at high temperatures, along with a rich slurry of minerals and simple chemical compounds. Energy is particularly concentrated at the steep chemical gradients of hydrothermal vents. There’s another line of evidence that points to hydrothermal vents: the Last Universal Common Ancestor of life, or LUCA for short. LUCA wasn’t the first life form, but it’s as far back as we can trace. Even so, we don’t know what LUCA looked like there’s no LUCA fossil, no modern-day LUCA still around
Instead, scientists identified genes that are commonly found in species across all three domains of life that exist today. Since these genes are shared across species and domains, they must have been inherited from a common ancestor. These shared genes tell us that LUCA lived in a hot, oxygen-free place and harvested energy from a chemical gradient like the ones at hydrothermal vents. There are two kinds of hydrothermal vents: black smokers and white smokers. Black smokers release acidic, carbon-dioxide-rich water, heated to hundreds of degrees Celsius and packed with sulfur, iron, copper, and other metals essential to life. But scientists now believe that black smokers were too hot for LUCA, so now the top candidates for the cradle of life are white smokers. Among the white smokers, a field of hydrothermal vents on the Mid-Atlantic Ridge called Lost City has become the most favored candidate for the cradle of life. The seawater expelled here is highly alkaline and lacks carbon dioxide, but is rich in methane and offers more hospitable temperatures. Adjacent black smokers may have contributed the carbon dioxide necessary for life to evolve at Lost City, giving it all the components to support the first organisms that radiated into the incredible diversity of life on Earth today
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