The Origin Of Organic Molecules On The Earth

Introduction,

Scientists estimate the earth formed 4.5 billion years ago this estimation comes from radiometric dating of the oldest rocks, meteorites and moon rocks.

For many millions of years, early Earth was pummeled by asteroids and other celestial objects. Temperatures also would have been very high (with water taking the form of a gas, not a liquid) The first life might have emerged during a break in the asteroid bombardment, between 4.4 and 4 billion years ago, when it was cool enough for water to condense into oceans However, a second bombardment happened about 3.9 billion years ago It’s likely after this final go-round that Earth became capable of supporting sustained life.

There are three different theories on how organic molecules came to be, the miller Urey experiment, the black smoker, and panspermia are the main three will be focused on in this report.

Miller-Urey Experiment

In the 1950s two biochemists Harold urey and stanley Miller conducted an experiment that showed that if seven different organic compounds could be formed suddenly by recreating the conditions of the early earth they designed an apparatus which is shown below that could hold a mixture of gases similar to gases in Earth’s early atmosphere, these gases were put over a pool of water which simulated the ocean.

The electrodes which are shown below created a spark which acted as lightning in the gas filled chamber they ran this for a week and examined the pool of water and to their surprise found that seven amino acids had formed formed from inorganic raw material, these organic molecules then grouped together and to form coacervates.

Their experiment partnered with hard geological, biological, and chemical evidence, gives Aid to the theory that the first life appeared suddenly through natural chemical reactions given the evidence there are still many skeptics who are unconvinced by this theory and a astrophysicist, ‘’Fred Hoyle, compares the likelihood of life appearing on Earth by chemical reactions ‘as equivalent to the possibility that a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein.”

Black smokers (hydrothermal vents)

Black smokers were first discovered by scientists aboard the Alvin in 1977, they were looking for hydrothermal vents in the ocean floor where hot lava flowed and mixed with seawater on the ocean floor and where tectonic plates were separating. the scientists aboard Alvin were stunned when they found an entire living ecosystem around the vents, living off bacteria around the vents.

Scientists had long believed that nothing could live at the great pressures found on the ocean floors and that all life on our planet requires sunlight to thrive. Both of these theories were proven incorrect in 1977 when the first hydrothermal vents were discovered.

Giant tube worms, long-necked barnacles, giant clams all lived in communities around the smokers. Since their discovery it has been found that a unique type of bacteria is able to metabolize large amounts of sulfur that is found in the superheated water that flows out of the vents. The bacteria are the basis of the food chain because no sunlight reaches these areas that are often over a mile deep.

These communities lend a hand to the fact hydrothermal vents are actually pumps these pumps would have powered life giving chemical reactions, scientists that back

this theory argue the conditions in vents create where heated, mineral loaded seawater flows form cracks in the seafloor created a gradient in positively charged protons that served as a fuel to the creation of organic molecules and proto-cells.

Panspermia

Panspermia is greek word that means seeds everywhere the panspermia states that these “seeds” of life exist all over the universe and can travel through space from one point to another it is thought that this is a possible way life could have started on earth.

Ways panspermia could have travelled through space include the deflection of interstellar dust by solar radiation pressure and extremophile microorganisms traveling through space within an asteroid, meteorite or comet.

There are 3 variations of panspermia

Lithopanspermia – impact-expelled rocks from a planet’s surface serve as transfer vehicles for spreading biological material from one solar system to another.

Ballistic panspermia – impact-expelled rocks from a planet’s surface serve as transfer vehicles for spreading biological material from one planet to another within the same solar system

Directed panspermia – the intentional spreading of the seeds of life to other planets by an advanced extraterrestrial civilization, or the intentional spreading of the seeds of life from Earth to other planets by humans

Evidence for panspermia was founded in 1984 by a team of scientists on a trip to Antarctica to search for meteorites, the meteor found was named Allan hills and in 1996 Allan showed that it contained structures that may be the remains of terrestrial nanobacteria.

Several tests for organic material have been performed on Allan and amino acids and polycyclic aromatic hydrocarbons have been found. However, most experts now agree that these are not a definite indication of life, but may have instead been formed abiotically from organic molecules or are due to contamination from contact with Antarctic ice. The debate is still ongoing, but recent advances in nanobe research has made the find interesting again.