The Geochemical Road to Life?

Hydrothermal vents occur when a crack in the Earth’s surface emits geothermally heated water.

“You came from an alkaline vent!” This flippant slight used to be more simplistic, “You came from a monkey,” at the time, representing a sardonic reference to the theory of evolution.

Either, but especially the former, may sound like an insult from a precocious juvenile, or perhaps even one coming from a GOP presidential candidate? More than that, it represents a better understanding of how we originated as living organisms through the confluence of geochemistry and biochemistry.

Actually, the alkaline vent origin seems to be the best guess coming from scientists regarding our own genesis. The state of scientific discoveries and the restless knowledge they engendered brought us this guess, representing theoretical progress coming from inquiry and a restless scientific curiosity.

Processes like plate tectonics, conduction of heat (like a spoon in hot coffee), and convection (like heated water rising to the top of a pot of boiling water), such knowledge contributed to the theory of hydrothermal vents at mid-ocean ridges as our origins. The first finding which advanced such theoretical guesses came in 1977 when hydrothermal vents were discovered at the bottom of the Pacific Ocean off Ecuador.

Scientists were shocked that there were creatures living in total darkness and at immense pressures, thus without the energy of sunlight.

Biologists came into the picture two years later to collect samples of microorganisms and larger animals at the vents using experimental collection devices, installed in the front of the submersible Alvin. These specimens they used to determine how living organisms flourished (eating and breathing). Such organisms, which get energy from vent chemicals, not the Sun, include octopi, tubeworms, zoarcid fish, clams, dandelions, shrimp, crabs, mussels and simple microbes. It was determined that these animals are grazers, not directly tied to a primordial birthing process.

The originally-discovered hydrothermal vents, called black smokers, the products of volcanic activity, were deemed too hot to spawn our origins. A vent with conditions more amenable to our derivation was discovered some twelve years ago, a vent warm and alkaline with mineral-rich water of about 40–90 degree Celsius. Scientists aboard the submersible, Atlantis, discovered it near the Mid-Atlantic ridge, calling it Lost City. This specific vent could have existed for some 100,000 years, but such vents would be even more common some 4 billion years ago with more ultramafic minerals across ocean floors, a time we associate with the origin of life on Earth.

Vents like Lost City furnish sort of a natural lab for studying this theory of how, some 3.7 billion years ago, life got its start in deep-sea hydrothermal vents. The surface of Earth – land and ocean – was not amenable to life then. A thin atmosphere of helium and hydrogen, followed by volcanic activity produced sulfur and carbon dioxide. All, including the surfeit of atmosphere, allowed the young Sun’s UV radiation to bake organisms near the surface at temperatures averaging above 100 degrees Fahrenheit. At the same time, the surface was littered with radioactive elements and bombarded with continual impacts from debris raining down from space.

A report in the journal Nature calculated that reconstructed proteins from ancient bacteria lived in a hot environment of 165 degrees Fahrenheit some 3.5 billion years ago, an environment that gradually cooled to an average of 100 degrees Fahrenheit by 500 million years ago. Genes evolve to adapt to environmental conditions, suggesting that complex creatures survive accordingly, the age of dinosaurs evolving, followed by the ascendency of mammals, this dominance most likely aided by an asteroid some 65 million years ago.

If life got started in hydrothermal vents some 3.5 billion years ago, where heated mineral-laden seawater spewed from cracks in the Earth’s crust, how did the resulting proto-cells power chemical reactions to make the building blocks of life: amino acids and nucleotides, for example? And how did such proto-cells, a self-organized, self-ordered, spherical collection of lipids, develop their own energy and leave this rocky incubation, eventually going from one cell to several connected cells?

In chemistry we know about the binding and bonding power of the electromagnetic force, from the negative proton in the nucleus of an atom to the positive electron and the joining of atoms into molecules. Cosmologists know that galaxies are made up of billions of stars bursting with atoms forming a colossal network of magnetic force. Our own Earth is protected from deadly radiation by a magnetic field, generated by the dynamo of a rotating Earth. Such magnetic force exists wherever there is matter.

Looking like stalagmites, the alkaline vents spew out mineral-laden seawater, harnessing carbon dioxide and hydrogen. The early ocean was acidic, filled with positively charged protons while the deep-sea vents erupted with alkaline fluid, rich in negatively charged hydroxide ions, according to Lane Martin. A natural charge gradient resulted from the negative-positive proton-ion interaction in the crucible of the iron-and-sulfur-rich walls of the vents.

Such a crucible was akin to a human placenta from which a baby gains separation by the cutting of the umbilical cord after birth, the energy of the mother’s blood flow transferred to the infant’s heart. In somewhat the same manner, though less complex, primitive cells leave the vent using a similar principle, somewhat comparable to a process seen with simple bacteria.

Existing archaea bacteria in deep-sea vents use a simple type of cellular pump that pushes sodium out of the cell while pulling positively charged protons in, something like a battery pack. The proto-cell membrane started out somewhat disorganized and leaky and perhaps over millions of years cohered into a similar sodium pump that accommodated more complex life forms (multi-cellular animals) as it severed its tie with the alkaline vent.

A complete video clip discussing the origin of life advances the current proposal that alkaline vents were involved in the origin of life. Vents provided compartments similar in size to cell membranes, as suitable for life as a fertilized egg in a placenta. Richly illustrated is the reverse Krebs cycle (reverse TCA cycle) which is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water.

If this sounds like fantasy, listen to a more complete, but simple hypothetical narrative of Earth and life’s development, details scientists have honed from multitudinous studies.

In primordial alkaline vents subatomic positively-charged protons interacted with negatively charged hydroxide ions to generate an energy gradient; the resulting dynamics produces a fledgling proto-cell; the proto-cell separates from the vent; it begins a multi-million year voyage in roily seas; evolves into complex creatures populating a planet’s restless oceans, continually roiled by a rapidly rotating planet and a close-orbiting Moon, an Earth-Theia castoff. The Earth’s rotation produces a magnetic barrier to deadly solar rays, protecting a budding life developing in the sea; sea creatures slowly adapt to land as oceans recede and the Earth’s rotation slows, the Moon slowly flung out; mammals evolve and as the landscape changes, developing the intelligence to cope, vulnerable to a new environment.

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